Determining whether hydroponics provides a benefit in plant growth in comparison to fertiliser

7/30/2019 Determining whether hydroponics provides a benefit in plant growth in comparison to fertiliser

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Determining whether

hydroponics provides a

benefit in plant growth in

comparison to fertiliser.

Muhammad Hashim

Chishty8170

May 2012


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Muhammad Hashim Chishty, Candidate number 8170, Centre number 33649.

Aim: To determine whether the hydroponics growing system provides a benefit in

plant growth compared to fertilisers.

Basic findings:All plant types grow to a higher average height when grown using

hydroponics.

Main trend:All plant types grow to a higher average height when grown using

hydroponics.

Null Hypothesis: There will be no differences in the heights of plants irrespective of

the growing technique.

Alternative Hypothesis: Plant height will be the greatest when using the hydroponics

growing technique.


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Research and Rational

Vegetation is thought to thrive in areas in which there is an abundance of vital resources

available to aid the growth of the plant such as an ideal balance of sunlight, water and various

nutrients. Chemicals are frequently used in agriculture to alter the characteristics of plants

and manipulate their quality to meet satisfy diverse operational needs. Hydroponics defines a

category of hydroculture (in which plants are grown in a soilless culture) where the essential

micronutrients (M) for maximum plant growth to their genetic potential are present in an

aqueous mineral nutrient solution or inert medium.

In recent time, a wide range of adaptations have been pioneered into the design process and

manufacturing methods concerned with hydroponics systems. Research and various different

environmental conditions have lead to overall improvements and a better understanding into

the fulfilment of definite crop growing needs. This presents an efficient demonstration of the

ingenuity and vitality of hydroponic soilless cultivation

Soilless cultivation can be referred to as the use of any technique of growing plants that does

not incorporate the use of the earth, fertilizers or composts and similar complexes. Various

names have been allocated to crop production without the usage of soil including

nutriculture, chemiculture, artificial growth, soilless agriculture, aquiculture and

olericulture. However, the most popular and widely referred to name that best describes this

process is undoubtedlyhydroponics.

Hydroponics takes advantage of the fact that green plants that grow without soil are entirely

dependent for their provisions of the vital inorganic elements upon solutions of nutrient ions

in water.

Figure 1, Image 1.

Early water or

solution culture

experiment in

hydroponics by J. Von

Sachs and W. Knop.

Plants were grown in

containers fitted with

supports for thestems and partially

filled with nutrient

liquid. Source :

Advanced Guide To

Hydroponics [1985]


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Research

During the time period, circa 1860 to 1900, the preparation of laboratory water cultures

became much standardised and the fundamental manner of using set compositions were

finally established. It was understood that the concentration of the nutrient solution used may

vary -/+ 0.1% - 0.6% and still generate optimal growth. The identification of ten of the

elements essential for healthy augmentation was paramount in the synthesis of a number of

nutrient combinations which were given official recognition in order to represent

hydroponics.

The following is the chemical composure knows today as Knops solution (1865) [After J. A.L. W. Knop (18171901), German chemist.

Chemical name Chemical formula Amount of substance in

grams

Potassium chloride KCl 0.12Monopotassium phosphate KH2PO4 0.25

Magnesium sulphate MgSO4 0.25

Calcium nitrate Ca(N03)2 1.00Ferric chloride FeCl3 Trace

Water H20 1000

The chemical composure ofSachsstandard formula (1860) (by plant physiologist J. v.

SACHS 1832-1897) differs slightly in chemical composition.

Chemical name Chemical formula Amount of substance in

grams

Potassium nitrate KCl 1.00

Calcium phosphate KH2PO4 0.50

Magnesium sulphate MgSO4 0.50

Calcium sulphate CaSO4 0.50

Sodium chloride NaCl 0.25

Ferrous sulphate FeSO4 Trace

Water H20 1000

Prior to the development ofSachsstandard, the importance of mineral nutrients was

established, however the confusion of which nutrients were required was a problem since the

composure of plants remains did not show if present elements were actually necessary for

plant survival or if they were simply a roughage, by product or contaminant.

J. V. SACHS discovered his hydroponic technique which allowed him to analyse the

influences of all ions on plant growth. He proposed that cations Ca2+, K+, Mg2+ and small

amounts of Fe2+ or Fe3+, as well as the anions H2PO4-, SO42-, and NO3- are essential for

plants to develop and sustain their endurance to external factors.


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J. V. SACHS proposed that certain chemicals were necessary for optimum plant growth but

in order to fully understand their function in plant development, the significance of each

compound is shown below.

Mineral Significance

Sulphur Component of amino acids and proteins,coenzyme A, aids the resistance of plants tobitter cold temperatures.

Magnesium A component of chlorophyll, counter ion ofATP

Calcium Regulatory functions, stabilisation ofmembranes, movement control and plays apart in the structure of the cell wall. Knownto act as a buffer and resists changes of alkalisalts and organic acids within a plant,maintaining a healthy pH.

Phosphate A major component of nucleic acids,involved in the phosphorylation of sugars andproteins. Promotes blooming and the growthof roots. Also a major source of energy.(ATP)

Nitrate The synthesis of proteins from amino acids,in nucleotides and chlorophyll. Increases fruitproduction and the quality of crops.

Potassium It is a co-factor for a large number ofenzymes and is essential for the regulatory

processes and synthesisChloride Is involved in osmotic processes and aidsplant metabolism.

Iron Vital for chlorophyll synthesis!

If we review both hydroponic compositions composed by J. A. L. W. Knop and J. V.

SACHS, it becomes apparent that all of the above minerals are present in both solutions.

Based on this fact, theoretically, plants grown in these solutions will bear a greater advantage

than those grown in standard soil for the sole reason that if a plant is given every nutrient,

mineral and chemical that it possibly requires in sufficient amounts, then the plant will grow

to the maximum size that its genetics will allow it to. Soils contain a mixture of these

nutrients, sometimes a surplus of one but lack sufficient quantities of the remainder,

sometimes contain a few but have none in surplus amounts but rarely ever contain them in a

perfect equilibrium as that in hydroponics solutions that have been perfectly engineered to the

specification of growth maximisation.

As the composition of soil varies significantly with location, using soil from one area does

not give an accurate overall representation of the nutrient composition of soils. To better

illustrate the potential of soil in plant growth, fertiliser will be referred to as soil. The main

purpose of fertilisers is to enhance the growth of plants and they vary in composition slightly.The average proportion of nutrients in fertilisers is illustrated below.


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It becomes apparent that fertilisers lack major macronutrients which can be found in both

hydroponic solutions that have been featured. To be deficient of nutrients would lead to the

assumption that fertilisers are disadvantageous to plant growth compared to soilless

cultivation techniques which provide the plant with nutrients such as calcium, magnesium,

sulphur, chloride & iron which are nota feature of traditional fertilisers. It was this

information which was beneficial in developing a hypothesis for this investigation.

The ultra structure of the cell wall of a plant distinguishes it from other cells in which it

contains specific features that only exist strictly in plants. The major organelles that are

present here but not in any other type of cell including animal cells are the cell wall, vacuoles

and chloroplasts.

In order to link the significance of chemicals and nutrients to a plant, the uptake and ultra

structure must be clearly defined as it plays a vital role in nutrient uptake.

Figure 2,

graph 1.

A pie chart

representing

the ratio of

nutrients in

fertiliser.


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The cytoplasm is one of

the key features of the

plant cell and consists of

a gel like substance that

resides between the cellmembrane.

It is this substance

which holds together all

of the cells internal

organelles in this

eukaryotic cell minus

the nucleus which is

separate and contained

inside the nucleoplasmwith the exception of

prokaryotes where the nucleus can be found within the cytoplasm itself. The majority of

cellular activities and processes occur here. Further analysis allows us to come across an area

of the cytoplasm known as the cytosol which is also a gel like substance. The cytosol is the

part of the cytoplasm that is not held within organelles and comprises of a complicated

combination of thin cytoskeleton filaments, molecular substances and water. The mesh of

fibres within the cytoskeleton contains a system of porous material and soluble

macromolecules, for example, proteins and calcium.

Another distinct feature of the plant cell is

the membrane bound organelle known as a

vacuole. It is suspended within the

cytoplasm and present plant and fungal cells

but only in a small percentage of protest

animal and bacterial cells. Vacuoles are

surrounded by their own type of cell

membrane known as a tonoplast and

restrain enzymes, molecules and remarkably

other substances which the vacuole may

have engulfed. They are largely formed by

the fusion of vesicles and retain no ordinary structure which can vary dramatically between

different species and organisms.

igure 3, image

2, showing the

ytoplasm in

he plant cell

ource:bms.westford

2011]

Figure 4, image

3, showing the

vacuole within

the cytoplasm.


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Nutrients present in both fertiliser and hydroponic solution which are only vital for

plant survival and play no role in yield maximisation.

Determinations of cystolic and vacuolar [K+] by use of compartmental analysis and

responses to [K+] deficiency have shown that cytosolic [K+] is held unvarying at the expense

of vacuolar [K+]. The initial reaction of plant roots to [K+] scarcity is the overall shift of

[K+] from roots to shoots. Homeostasis is accomplished via changes in [K+] transport at the

root plasma membrane and the tonoplast (the membrane of the vacuole discussed earlier).

[K+] is responsible for providing plants with appropriate ionic environments for processes

within the cytosol and is paramount in growth regulation. It is used for the regulation of the

opening and closing of the stomata which then links to gaseous exchange and cell turgour and

not only is [K+] significant for regulatory purposes but it is also necessary for the synthesis

of proteins via amino acids.

Phosphorus

The functions of this nutrient cannot be performed by any other and its adequate supply is

essential for optimum growth and reproduction. Phosphorous is taken up as the

orthophosphate ion [H2PO4-] and [HPO4=]. It is incorporated into organic compounds such

as DNA, RNA, phospholipids, enzymes and importantly, adenosine triophosphate (ATP).

This is the supply of energy that coerces a multitude of energy driven chemical reaction

inside the plant. Phosphorous is major constituent in the building blocks of genes and

chromosomes and is a vital part of conveying genetic information from one generation to the

next.

Nitrogen

A source of nitrogen is an essential element of the proteins that produce cell material and

plant tissue. In addition, it is required for the function of biochemical agents such as

chlorophyll (the substance which allows the process of photosynthesis possible), enzymes

(which aid organisms to carry out biochemical processes and incorporate nutrients) and

nucleic acids (DNA & RNA). The nitrogen present in soils is due to the fact that nitrogen gas

comprises of a huge 76% of the earths atmosphere. However, the nitrogen present in soils isof a sort that cannot be directly accessed by plants. It is for this reason that the nitrogen found

in chemical fertilisers is a form that can be used immediately by plants after a succinctconversion


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Nutrients present in proposed hydroponic solution which play a role in yield maximisation.

As these are present in only one of the growing techniques, it is the role of these that will

determine any differences between hydroponics and fertiliser growth techniques.

Calcium

In many cases, calcium fertilisation has been disregarded and only considered after the

development of deficiency disorders whilst large firms are in pursuit of economic prosperity

to produce crops of quality and value.

The thickness and strength of the cell wall is substantially increased by the addition of

calcium. This nutrient plays an essential part of the cell wall and provides the plant with

extensive structural rigidity by making cross links inside the pectin polysaccharide matrix.

The major benefit that accompanies calcium uptake to plants is disease reduction. Bacterium

and fungi infect the tissue of plants by releasing by products which can dissolve the middle

lamella. Increasing the calcium content of a plant lowers the effectiveness of bacterial andfungal by products and therefore protects the plant from infection. Many plants have been

described to have narrow uptake windows for calcium and uptake is enhanced to a large

extent where calcium is available in a soluble form. This is the case insachs standardwhere

calcium is sourced from both calcium phosphate and calcium sulphate which means it is

immediately available for uptake. Disease reduction is not directly relevant to my

investigation as the plants concerned were grown in an environment very different to a farm

where such feature is substantially beneficial, however, due to calcium being present in

sachs solution, its role will still be considered.

Theoretically, calcium deficiency causes a host of issues for plants and the reasons are

diverse and complex. Problems caused by a lack of calcium that can be immediately noted

include the death of various growing points on the plant, abnormally large amounts of dark

green leaf, the premature shedding of buds and weakened stems.

Figure 5, table 1,

showing the

effect of calcium

on bacterial

pathogen

infection.

Source:

Calciums Role

In PlantNutrition [2002]


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Magnesium

Magnesium sustenance in plants is often ignored and the shortage of this nutrient has adverse

effects on plant growth. A faction of essential plant functions depend on sufficient supplies of

magnesium such as root formation, photosynthesis and chlorophyll. Magnesium influences

reactions such as photophosphorylation (ATP formation in the chloroplasts), CO2 fixation,

synthesising of proteins and the production of oxygen. Numerous critical biochemical and

physiological procedures are affected by magnesium deficiency, ultimately leading to

impairments in growth and yield. It is also known to activate specific enzymes when it is

present in a considerable amount such as ribulose-1, 5-biophosphate or RuBP which is in the

photosynthesis process. It is also the most abundant enzyme on the face of the earth.

Excessive amounts of potassium (generally found in fertiliser) usually further aggravates the

stress caused by magnesium deficiency as the plant mistakes the potassium for magnesium

and incorrectly uptakes this nutrient. As magnesium is the central atom of chlorophyll,

deficiency usually results in degradation of chlorophyll in older leaves and the main symptomto become apparent, chlorosis, a distinct yellowing between the veins of leaves and necrosis,

the premature aging and

death of cells.

Figure 5, image 3,

comparing plant

leaves with low

magnesium levels and

adequate magnesium.

Source: Magnesium, Aforgotten element.

[2010]

Figure 6, image 4,

comparing plant leaves

with low magnesiumlevels and adequate

magnesium. Source:

Magnesium, A

forgotten element.

[2010]


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Sulphur

The amounts of sulphur that is required as a plant nutrient is low, approximately 20 pounds

per acre of land, nevertheless it is substantially beneficial to plants as a nutrient, important forprotein formation. Deficiency is illustrated as a slight yellow fade on upper leaves. Sulphur

deficiency should not be confused with nitrogen deficiency as the characteristics of

deficiencies are very similar, distinguished by the fact that sulphur deficiency leads to a

yellow fade on younger upper leaves whilst tending to be on lower, older leaves for nitrogen.

90% + of the total sulphur of most soils is found within organic matter which is naturally

mineralised into organic sulphur (the sulphate ion, SO4S) which can be taken up by theplant. Sulphur makes its way to the roots of a plant through the atmosphere (sulphur dioxide

gas), through soil minerals already present, via pesticides, organic wastes such as manure,

sulphur containing irrigation water and fertilisers.

Figure 7, image

5, showing

sulphurs life

cycle in the

environment.

Source: Sulfur

deficiency

symptoms.

[2005]


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The term plant growth may have become too generalised and vague to describe the complex

process which a plant undergoes whilst growing so it is described here.

Growth of a plant is the change in size of plant organs and cells due to cell division andenlargement. Enlargement demands the elasticity of the cell walls to change and the increase

of the water content in the vacuole. Growth can generally be divided into two categories,

determinate (where the organism reaches a specific size and ceases to grow any further) and

indeterminate (where cells will continue to keep dividing indefinitely) as is the case for

plants.

Plant growth occurs in regions known as meristems. These are areas of repeated division of

cells which later on will become specialised and relate to their specific function.

There are two types of meristems, apical and lateral; the apical meristems are the area ofprimary growth in a plant and these are found at the shoots and roots where unspecialised

cells are found and will undergo mitosis, elongate and eventually become specialised to carry

out a particular task and then become part of permanent tissue within the plant. This cycle

continues as growth continues.

Lateral meristems, as the name suggests grow from the side of plants and instead of growing

upwards and contributing to plant height, lateral meristems relate to the thickening of plants

and structural support. Eventually new layers form the vascular bundle which contains the

xylem and phloem which boosts transportation around the plant. The secondary layer

continues to expand and gaps form in the cambium and allow gaseous exchange to take place

so that carbon dioxide from the external environment can be incorporated into the plant.

Figure 8, image

6, showing the

meristem

regions present

in the root and

shoot. Source:

Click4biology

[2010]


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Rationale

Advances in our understanding of biochemistry have lead to major breakthroughs in scientific

awareness and the ability to manipulate and take advantage of extensive knowledge to benefitin (in this case) plant yield. Large scale events in history were central to the dogma that

farming was the mainstream method to feed and sustain a population and when a lack of

knowledge prevailed with respect to safe and reliable crop production (in the case of the Irish

famine 1845-1851) massive famines occurred leading to the demise of millions of men,

women and children.

It was intriguing to discover that advances in this field which could have potentially saved

millions of lives and changed the demographics of an entire country became standardised

only 9 years after the end of the Irish potato famine by the synthesis of sachs standard andknops solution. Perhaps such a large scale event was a catalyst for such research and

development as both hydroponics solutions have the ability to maximise plant yield to what is

genetically possible and provide crops with chemicals not normally found in soil fertilisers let

alone soil such as magnesium, sulphur and calcium which plays a major role in the

strengthening of the cell wall and middle lamella and significantly reduces the effectiveness

of bacterial and fungal activity. The rationale behind this investigation stems from curiosity

behind the anonymity that if hydroponics growing systems were developed and implemented

prior to major crop related famines such as the Irish potato famine; could such disasters have

been avoided?

The reality is that even today, where a variety of growing techniques are known of and

practised, famines still occur with catastrophic implications in the developing world such as

in parts of Asia and in the horn of Africa. There is ambiguity here as perhaps such regions

lack up to date knowledge of biological principles with regard to growing systems and so are

unable to do so or do possess the knowledge but cannot endeavour to do so due to

economical repercussions. The rationale explicitly was to conduct an experiment to determine

whether hydroponics growing techniques really do benefit plant growth substantially and if

this is the case, is the process economically viable? It was the opportunity to address this

issue that lead me to conduct this investigation using three types of food crops, garlic, parsley

and coriander. If the results of this investigation provide to be promising, then under every

circumstance will findings be communicated to agricultural agencies based within countries

plagued with crop related famines in recent history.


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Plants will grow differently in different locations as the faction of nutrients available for

plants differs per area and so it can be deduced that the content of soil or any other medium

has a direct impact on the characteristics of the plant grown therein. The different nutrients

broken down into their components gives an insight into their specific contributions to the

plant which helps in providing a context for the investigation to be conducted as it is these

very nutrients that distinguish between the constituents of fertilisers and hydroponics

solutions and so will be the reason for any differences in plant growth.

As there is a feasibility to manipulate these nutrients and the method of transferring them to

the plant, the rationale for the investigation is very much supported in that it becomes

possible to test plant growth by controlling the relevant nutrients administered to it and

measuring the differences (if any) that the plant experiences in its development. If the

investigation does confer to the alternate hypothesis, then a decisive conclusion can be made

regarding why hydroponics is beneficial to plants linking into the breakdown of the nutrients

in this section.

Examination of the individual nutrients allowed analysis of which growth mediums would be

most appropriate and this had a direct link to its implementation in the planning section as it

was important to determine which hydroponics solution would be the most effective in

comparison to fertiliser.


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References and Sources:

BassiriRad, H. 2005. Nutrient Acquisition by Plants, An Ecological Perspective. Volume 181

Cakmak, I. Yazici, M.A, 2010. Magnesium: A Forgotten Element in Crop Production, Better Crops/

Vol.94, No.2 p23&24.

Cell Structure, 2010. Image of cell. [online] Available at:

http://bms.westfordk12.us/pages/teams/7green/cells/GroupH/Hindex.html [Accessed 28 November,

2011]

Douglas, S. J. 1985.Advanced Guide To Hydroponics-[Soilless Cultivation]

Easterwood, G.W,2002. Calciums Role In Plant Nutrition, p1&2.

Functions of Phosphorous in plants, 1999. [online] Available at:http://www.ipni.net/ppiweb/bcrops.nsf/$webindex/ECBABED567ABDCDD852568EF0063

C9F4/$file/99-1p06.pdf[Accessed 8 January, 2012]

Hergert, G.W, 2005. Sulfur, Deficiency Symptoms, p39-43.

Mineral Nutrients, 2003. [online] Available at:

http://www.biologie.uni-hamburg.de/b-online/e16/16a.htm [Accessed 7 December, 2011]

Plant Nutrients, 2004. [Online] Available at:

http://www.ncagr.gov/cyber/kidswrld/plant/nutrient.htm [Accessed 2 February, 2012]
http://bms.westfordk12.us/pages/teams/7green/cells/GroupH/Hindex.htmlhttp://bms.westfordk12.us/pages/teams/7green/cells/GroupH/Hindex.htmlhttp://www.ipni.net/ppiweb/bcrops.nsf/$webindex/ECBABED567ABDCDD852568EF0063C9F4/$file/99-1p06.pdfhttp://www.ipni.net/ppiweb/bcrops.nsf/$webindex/ECBABED567ABDCDD852568EF0063C9F4/$file/99-1p06.pdfhttp://www.ipni.net/ppiweb/bcrops.nsf/$webindex/ECBABED567ABDCDD852568EF0063C9F4/$file/99-1p06.pdfhttp://www.biologie.uni-hamburg.de/b-online/e16/16a.htmhttp://www.biologie.uni-hamburg.de/b-online/e16/16a.htmhttp://www.ncagr.gov/cyber/kidswrld/plant/nutrient.htmhttp://www.ncagr.gov/cyber/kidswrld/plant/nutrient.htmhttp://www.ncagr.gov/cyber/kidswrld/plant/nutrient.htmhttp://www.biologie.uni-hamburg.de/b-online/e16/16a.htmhttp://www.ipni.net/ppiweb/bcrops.nsf/$webindex/ECBABED567ABDCDD852568EF0063C9F4/$file/99-1p06.pdfhttp://www.ipni.net/ppiweb/bcrops.nsf/$webindex/ECBABED567ABDCDD852568EF0063C9F4/$file/99-1p06.pdfhttp://bms.westfordk12.us/pages/teams/7green/cells/GroupH/Hindex.html


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Source 1

Information acquired by this source was in light of how nutrients are taken up by plants and

was found in volume 181 of a book series authored by Hormoz BassiriRad. Researchallowed me to discover that Hormoz BassiriRad is a physiological plant ecologist whom uses

observational and experimental approaches to develop his understanding of how plants

behave and respond to natural stresses and pollution. Hormoz BassiriRad is a professor at the

University of Illinois, Chicago and is a holder of a PhD in plant physiology which he

obtained at the University of Arizona in 1990. Both universities in the USA are large and

well established institutes of higher education that boast world class modern equipment and

have a combined endowment of more than $2.6bn which concludes that information sourced

from either universities or Dr Hormoz BassiriRad is of significant reliability and more than

credible to meet the demands required by this investigation in terms of validity. Dr Hormoz

BassiriRad boasts an extensive portfolio with an array of publications not only by himself,

but in collaboration with other leading scientists in the field and constantly conducts large

scale experiments and extensive research to thoroughly extrapolate his knowledge and

understanding in the field of plant biology.

Source 7

The article that presented the importance of sulphur was in part 1 of a series of online

published articles by the author, Gary W. Hergert whom is a professor of agronomy (Thescience of soil management and crop production) and horticulture at the University of

Nebraska, Lincoln and holds three degrees, a bachelor of science in agronomy, a masters ofscience in agronomy and a PhD of agronomy. Similar to the previous author, Dr Hergert has

published a display of books, articles and journals dating back to the 1980s and is a

professional member and fellow of the American Society of Agronomy and Soil Science

Society of America which are prominent international scientific societies. Dr Gary W.

Hergert is extensively literate in the field and thoroughly knowledgeable of his peer reviewed

publications which render this source credible in terms of reliability and validity.

Source 2

An article written by two doctors, Dr Ismail Cakmak and Atilla M. Yazici is immediately of

potential worth due to the professionalism of the authors. Dr Cakmak obtained a BSc in soil

science and plant nutrition at the Cukurova University in Turkey but progressed to a full PhD

in plant nutritional physiology from the Stuttgart-Hohenheim University which is one of

Germanys leading universities in agriculture. Dr Ismail Cakmak was the receiver oftwoawards from the scientific and research council of Turkey in 1994 and 1999 and has a library

of online articles accessible via the Sabanci University website, the university at where he

currently works. Dr Mustafa Atilla Yazici is also a faculty member at this university and

holds a total of three degrees, a BSc, an MSc and a PhD in soil science and plant nutrition.

Their combined work in this article lead me to believe that the publication would be of a highstandard, reflecting the extensive combined knowledge of plant biology.


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Trial 1

This is the initial trial and its sole purpose is to decipher whether traditional germination

procedures are appropriate in order to successfully initiate the germination of seedlings andthen limited further growth. Controls in this trials will be limited if any and the results,

analysed and manipulated to select the best possible growing technique for the set of control

plants that will be directly compared with another set of plants growing using hydroponics

techniques. Three types of seeds will be used in this trial experiment:

Parsley

Coriander

Garlic

Methodology for trial 1

1. Dampened cotton wool pieces and forced this into a test tube half filled with water in

order to keep the cotton wool moist at all times. Care was taken to ensure that the

cotton wool is semi submerged so that the top is only damp and not submerged in

water.

2. Placed three parsley seeds maximum onto the moist cotton wool and separate out to

give seeds sufficient space for germination if trial is successful.

3. Repeated steps 1 & 2 but this time with three coriander and garlic in order to achieve

a setup where there are three test tubes, each with different plant types.4. Labelled all test tubes with the appropriate seed name and place inside a test tube

rack.

5. Placed the test tube rack in an area where there is an abundance of light, for example

near a window or inside a propagator. In this trial, the test tube rack was left adjacent

to a window, exposed to direct sunlight.

6. Left the test tube rack for a minimum of one week and within that time, performed

visual checks every day looking for evidence of seed germination.

Result for trial 1

Upon inspecting the test tube rack after 1 day, the cotton wool still appeared to be moist,

ensuring that the seeds would not dehydrate, the seeds showed no sign of germination and

considering that sunlight, water and oxygen was available to the seed and that it had only

been one day since the start of the investigation, the experiment was given more time.

Inspections upon days two through six showed identical results and upon day seven there was

a sign of germination in the test tube containing garlic seeds. The results were negligible.


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Since the percentage of seeds that germinated was so low, this method was abandoned and

the medium in which the seeds were planted was changed for trial number two in aspiration

of more successful germinations.

Trial 2

Aim: The aim for this trial is to determine a method to successfully germinate seeds to a

suitable length. The failure of trial 1 meant that a more successful technique was required.

Methodology

1. A tray with holes in the bottom (of size 50cm x 28cm with a depth of 6cm) was filled

with industrial fertiliser.

2. Five of Parsley, garlic and coriander seeds were planted in alternating rows across the

length of the tray with fertiliser completely covering the seeds.

3. Each row was labelled with the appropriate seed name to ensure differentiation.4. The whole tray was then placed inside a 55cm x 30cm tub which was filled with

water. The holes at the bottom of the tray allowed water to saturate the fertiliser.

Figure 9, image

7, showing the

tray of seeds intrial number 2.


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Day Parsley Coriander Garlic

1 No growth at thistime, nothing couldbe seen above soil.

No growth at thistime, nothing couldbe seen above soil.


2 No growth at thistime, nothing couldbe seen above soil.

Plumule was seenemerging fromseed.


3 Plumule was seen

emerging fromseed.

Plumule became

larger and begangrowing.

Plumule was seen

emerging fromseed.

4 Radicals becamelonger and rootswere present.

Radicals developedand roots becamelong.

Radicals and rootswere present.

5 Root continued togrow.

Stem becameapparent, rootscontinued to grow.

Stem becamevisible.

6 Stem started toappear.

Stem had becomelonger at this point.

Stem had becomelonger.

7 Stem had becomemore lengthenedand roots werelong.

Stem was long androots hairs haddeveloped.

Stem was muchlengthened and theroots had alsobecome very long.

Results show that this method of germination promotion is much more effective thanin trial one. Seeds germinated and grew rapidly with evidence of stem formation

observed as early as day five.

In this experiment, these three plants grown using industrial fertiliser will be the

control variable and grown for seven days and then compared with identical plants

grown in different growth mediums such as hydroponics solutions.


20/39


The experiment in trial 2 was used to investigate and establish a more efficient

method of seed germination than the method used in trial 1. Since trial 2 was

successful in establishing a reliable and effective seed germination technique, it will

be used again in trial 3, this time not to measure seed germination success, but thelength of the shoot of the respective plants, garlic, parsley and coriander. Trial 2

allowed me to realise the importance of control variables which will now be

controlled in the next trial

Trial 3

1. 500 grams of industrial fertiliser was measured and placed inside a tray (of size 50cm

x 28cm with a depth of 6cm).

2. 10 seeds of each type were placed inside the fertiliser in rows.

3. They were then watered with 300 millilitres of water for a week; also another control

variable within this trial. The 200 grams of the organic fertilizer was one of the

control variables. The plastic tray was then placed on a windowsill so the seeds could

receive natural light.

4. Measurements were then taken for the next week with a vernier calliper

5. . This is an accurate way of measuring the length of the shoots, with measurements

being made in mm.

A variable that was impossible to control was light. As the apparatus was placed upon a

windowsill, the source of light was the sun, as opposed to a lamp which could be easily

controlled. As the experiment ran for a short period of time at the same place and within the

same time of year, the impact of not being able to control this variable was minimised.

Control Variable Effect of different conditions How am I going to control thevariable

Volume of water Measurements of the amountof water given to the plantswere kept constant in order toensure validity. Also anychanges in the water amountcould affect the growth of theplants height.

Using a measuring cylinder.

300ml of water was used.

Volume of organic fertilizer The amount of fertilizer givencould considerably affect the

results of the experiment.Therefore measurements ofthe amount was taken.

Using scales.

500 grams of organicfertilizer.


21/39


The Average Length of Shoots in industrial fertiliser of 10 seeds of corresponding seed type in

millimetres.Type ofSeed:

Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7

Parsley 0 6.1 13.4 20.8 27.3 34.2 36.4

Coriander 0 5.9 14.1 22.0 28.4 35.0 41.1

Garlic 0 8.0 17.7 27.8 34.8 41.8 50.9

The results of this trial show that the largest increase of shoot length over 7 days was the

garlic plant followed by coriander and then parsley. The aim of this trial was solely to obtain

data on the germination and length of shoots over a period of 7 days that can be directly cross

compared with germination of the same seeds using hydroculture instead of traditional

fertiliser. The use of 10 seeds of each type was manageable and a mean, easily calculated.

For trial number 4, my final trial, the seeds were grown using a method of hydroculture

known as hydroponics. They were grown using the well established formula of sachsstandard containing a complex compilation of nutrients and chemicals engineered for

maximum plant yield. Bearing in mind that this process involves the suspension of plant roots

in the hydroponic solution, this renders seed germination using this technique implausible as

using hydroponics would saturate the seed. For this reason the seeds were germinated using

the method from trial 2 and then immediately transferred into the hydroponic solution during

day 2 when there was evidence of sufficient root formation.

The largest increase in plant size for all three plants occurred during the period between day 1

and 2 where all plants more than doubled in their size. Growth rate decreased after this period

but still occurred at a steady rate up until day 7 when the trial was stopped.


22/39


Final experiment

Risk assessment

The plants were removed from the fertiliser at day number 2 which meant certain precautions

had to be taken before touching this material. Gloves were worn during this process to ensure

the prevention of bacterial contamination and infection from fertiliser coming into contact

with cuts or other vulnerable areas.

A major issue facing hydroponics gardeners is the development and sustained growth of

salmonella in plant systems. The impact of this was minimised by ensuring conditions in my

final experiment do not match that which are preferred by salmonella bacterium. One of such

conditions is the presence of a humid environment, similar to that found in conventional

greenhouses where hydroponics systems are used to cultivate vegetables on an industrial

scale. In order to minimise this, the simple hydroponic system that was used was set up and

placed upon the windowsill of a cool and ventilated classroom equipped with an air

conditioning unit which meant that the temperature never exceeded 15 degrees Celsius during

the 7 day period. The opening of the windows at regular intervals during the experiment

ensured that a light breeze eliminated any risk of sustained humidity (if ever present) and also

reduced the risk of dampness which also promotes salmonella growth. Humidity is a problem

at one end of the spectrum however cold, stagnant solution is also a promoter of bacterium.

The risks of this was minimised by the replacement and replenishment of sachs solution at 2day intervals and a constant monitoring of solution temperature with the use of a

thermometer. Lastly, there was an emphasis on cleanliness to eliminate the risk of infections

spreading. This was controlled by monitoring the plants and ensuring any dead leaves were

removed of and discarded immediately.

These precautions were a direct barrier from infection of salmonella bacterium which in some

cases can be fatal and involve mild symptoms including nausea, vomiting, fever, cramps,

diarrhoea and headaches. In some cases, infected individuals may experience Reiterssyndrome which is characterised by acute pains in the joints, irritation of the eyes andpainful urination.

The resistance of plants to mould is amplified in the presence of potassium (K) so as a pre-

emptive measure, sachs standard was chosen over knops solution as sachs standardcomprises of a substantially larger amount of potassium.

It was of paramount importance to carry out risk assessment and take into account

precautions whilst carrying out the final experiment to prevent salmonellois as the

consequences of ignoring such procedures are potentially costly and hazardous to health


23/39


Control Effect of this and reasoning behind it How was this variable

controlled?The volume ofhydroponics solution(sachs standard)

The measurement of the volume of thesolution that the plants are grown inwas kept constant after thereplenishment in order to ensurevalidity as any changes to consistencymay have effects on the plants growth.

By the use of a measuringcylinder.

How often thesolution isreplenished

This step ensures that there is nostagnant solution left inside of thepropagator for long periods of time.This is an issue as the stagnant solution

may be a factor contributing tosalmonella growth and also result inthe various salts to assimilate at thebottom of the propagator.

Solution was made up using200 grams of sachs solutionfor every litre of water and wasdone every 2 days to replace

old solution.

Mass of organicfertiliser that theplants prior to day 2were grown in.

Using very small amounts of fertiliserwould not be effective and would notgive the desired outcome of seedgermination to a sufficient extent. Asimilar amount of fertiliser was used inthis experiment to that used in trial 2 asit proved effective in seed

development. This was weighed outwith the aid of electronic scales andwas 400 grams.

400 grams of fertiliser wasused due to it being sufficientin trial 2.

Amount of seedsused

A small number of seeds would resultin an investigation that is not as validor reliable as one with many seeds. Alarge number of seeds would increasethe validity of the investigation butwould increase the chances ofanomalies occurring and make

calculations unmanageable.

In this experiment, 10 seedswere used. This is a sufficientamount to obtain a wide rangeof data of such kind andensures a degree of validity.This amount also provedappropriate in earlier trials

where a mean was easilycalculated.

Precision

Precision in this experiment

was key; in order to produce

a set of results that are very

reproducible, the manymeasurements in this

gure 10,

mage 8,

howing

gital scales

sed to

easure theass of

rganic

ertiliser.


24/39


experiment needed to be precise. This increased the validity of this set of data and in turn, the

ultimate value at the end of the experiment resulting in a value that is close to the true one

therefore establishing accuracy.

When deciding upon which apparatus is best appropriate for measuring the mass of the

organic fertiliser, it was between digital and analogue scales. Analogue scales were similar in

operation to digital scales and provided the same result however the fact that there is a

probability of human error in the interpreting of the mass of fertiliser with regard to the

position of the needle on analogue devices being subjective, the digital scales was used. The

electronic digital scale provided precision readings of the fertiliser mass provided that the

scales were calibrated to zero every time whilst harnessing the container in which the

fertiliser was to be held.

The most frequently used apparatus in this experiment was the vernier caliper. Whilst

determining the length of shoots, its small scale divisions allowed for the ultimate precision,

the reason for which it was chosen over a ruler. Measurements, taken in millimetres ensured

that no part of the

shoot was left

unaccounted for and

with a reading error

of a mere 0.05 mm,

it was certain that

this apparatus was

sufficiently

appropriate inlength

determination. Its

operation involved

placing the shoot

between the jaws of the caliper and tightening accordingly. After

tightening, the measurement can be read by referring to the scale on

the vernier caliper.

The apparatus which was used to measure volumes of water which

was used to dampen the cotton wool in trial 1, water the seeds in trial

2 & 3 and make up appropriate hydroponic powder: water ratios was

the measuring cylinder. This, similar to the vernier calliper uses

millilitre measurements as opposed to millimetre, both being small

sub units, which can be found on the side of the graduated cylinder

ensuring an acceptable degree of precision.

When reading from the digital scale, the chances of human error

occurring are insignificant due to the display reading. When reading

from the vernier caliper, the chances of human error are higher but

Figure 11,

mage 9,

showing a

vernier

caliper

used to

measure

plant

shoot.

Figure 12,

image 10,

showing

the

transfer of

water into

a

measuring

cylinder.


25/39


this is minimised due to the presence of the vernier scale which allows the reading to become

clear.

In the case of the graduated measuring cylinder, the problem of subjective interpretation

again comes to mind as the two different liquids (the hydroponics solution and the water) can

tend to behave differently whilst inside the cylinder, making it harder to read the

measurements, hence increasing the chances of human error.

In order to minimise the effects of this, when reading from the cylinder, the value which was

used was that which was at the base of the meniscus. The meniscus is a slight curvature of

liquid inside the sides of the cylinder which is a result of static charges ensuing in liquid to

stick inside the walls. Measuring from the base of the meniscus and not the sides ensured

maximum precision and is a skill I obtained from conducting chemical titrations. To put this

into context, it is illustrated below.

Stringent techniques in the measurements throughout the experiment resulted in data that was

as close to the true value as could be possibly made in the given circumstances resulting in

accuracy. This data was ready to be processed into information that can answer the main

question within this investigation.

Method

1. 500 grams of industrial fertiliser was measured and placed inside a tray (of size 50cm

x 28cm with a depth of 6cm).2. 10 seeds of each type (parsley, coriander and garlic) were placed inside the fertiliser

in rows.

3. They were then watered with 300 millilitres of water for a week; also another control

variable within this trial. The 200 grams of the organic fertilizer was one of the

control variables. The plastic tray was then placed on a windowsill so the seeds could

receive natural light.

4. Sachs solution was made up by dissolving 200 grams of sachs powder into everylitre of water. The amount chosen was 300 grams in a total of one and a half litres of

water.5. This was mixed and poured into a propagator in which the seedlings were placed.

Figure 13,

image 11,

showing the

procedure of

measuring from

the base of the

meniscus to

ensure

precision.


26/39


6. All seeds were removed from the organic fertiliser at day two, the fertiliser was washed

from the newly developed roots and these roots were then suspended inside the sachshydroponics solution.

7. Fresh solution was prepared in exactly the same composition as the old solution and

replaced the old hydroponic solution every two days until the end of the experiment.

8. Measurements were then taken for the next five days with a vernier calliper.

Figure 14,

image 12,

showing the

propagator into

which the

plants were

placed after

two days of

growth inside

fertiliser.

Figure 15,

image 13,

showing the

propagator with

garlic plants

(right), parsley

and coriander

plants (left)

during day

seven of the

experiment.


27/39


Table showing heights of parsley plants during when they were in fertiliser (days 1-2)

and in hydroponics solution, (days 3-7)

Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7Seed

number:

1 0 6.0 17.5 24.3 30.9 37.8 42.6

2 0 5.8 18.8 25.2 33.5 39.3 44.1

3 0 4.9 16.0 23.9 33.1 38.88 43.5

4 0 6.6 16.8 23.8 32.4 37.9 44.9

5 0 6.3 17.2 26.4 32.6 38.2 42.9

6 Negligible 6.1 18.2 25.9 35.0 39.4 44.2

7 0 5.8 11.0 20.9 29.2 35.2 40.8

8 0 5.5 16.7 25.5 32.5 36.9 42.99 0 6.1 17.3 26.6 33.6 37.8 43.8

10 0 6.6 16.2 25.9 34.4 38.8 44.3

Average

Length

(mm)

0 6.56 16.57 24.84 32.72 38.01 43.4

Figure 16, graph

2, showing the

comparison

between the

parsley plants in

two growth

mediums.


28/39


After ensuring measurements were taken from ten different seeds using precision techniques,

it was evident whilst transforming the raw data into information via graph construction, that a

trend was present.

The graphs illustrated in blue, green and red, each correspond to their seed type, parsley,

coriander and garlic respectively and show the growth of seeds in sachs hydroponicssolution and regular fertiliser. With respect to the hydroponics data, it should be apparent at

this stage that up until day two, all seeds were grown in fertilisers in order to acquire

sufficient mass so that immersion of roots in hydroponics solution may become possible and

effective; therefore data collection during days one and two referring to both hydroponics

solution and fertiliser were carried out in identical circumstances, using the same apparatus,

techniques and controlling the exact same variables. As expected, the results between days

one and two on all graphs are so similar, that it appears that they have been almost

superimposed unto one another.

The parsley seeds in fertiliser grew at a substantial rate, much faster than that which was

predicted, increasing at a steep positive correlation from day one until six before levelling out

at day seven with a maximum average value of 36.4milimetres. These values were taken for

cross comparison with the same seed type grown using a different technique.

With respect to the shoot length of parsley seeds in hydroponics solution, there was rapid

growth between days one until six. At day number one, the length of the seed shoot was very

much in its premature stage and was recorded to be zero or slightly above zero in which case

it was recorded as negligible due to there not being a small enough scale to measure this with.

Day two saw a considerable change to the physical attribute of the seeds where it becameobvious rather than subtly apparent that the shoot had burst through the seed and was

measurable at an average height of 6.56 millimetres as opposed to zero the previous day. Day

three resulted in the combined average height of plant shoots to increase by more than 2.5

times, standing at 16.57mm. It was also noted that seed number seven had a noticeably lower

height than the other nine seeds but was included in the average value calculation. Day four

saw an increase by factor of almost 1.5 at a mean of 24.84mm and the lowest value was seed

number seven which was the anomaly the day before. This was later categorised as a

systematic error which continued into the latter days. The average length of shoot at day five

was higher than that of day four at 32.72mm however it was noted that the rate of successive

shoot length growth was steadily decreasing, this time being at 1.3 times the previous figure.

The lowest value was again associated with seed number seven. At the penultimate day of the

end of the experiment, the shoot length was 38.01mm and at the last day, 43.4mm which was

the slowest rate of growth so far at 1.14 times the previous value. Being day seven, the

experiment was stopped and all values recorded for statistical analysis,

It was noted that every value of every day of every seed grown using sachs standard wasnoticeably higher than the values of seeds grown using fertiliser.


29/39


Table showing heights of coriander plants during when they were in fertiliser (days 1-

2and in hydroponics solution, (days 3-7)


Seed

number:

1 0 5.7 18.4 26.4 32.3 40.4 49.3

2 0 5.8 19.9 26.0 34.8 42.2 48.4

3 0 5.5 18.8 26.7 34.4 40.1 47.7

4 0 5.9 18.4 26.4 33.9 40.9 48.9

5 0 6.2 18.8 29.1 33.3 43.4 47.7

6 Negligible 6.1 19.0 26.6 30.0 39.9 49.8

7 0 5.9 16.8 24.5 34.3 38.3 48.8

8 0 5.3 17.8 27.3 33.9 41.1 49.2

9 0 5.9 18.6 26.6 34.4 41.2 50.110 0 5.8 18.8 26.4 35.8 42.2 49.6

Average

Length

(mm)

0 5.81 18.53 26.6 33.71 40.97 48.95

Figure 17, graph

3, showing the

comparison

between the

coriander plants

in two growth

mediums.


30/39


Referring to the coriander seeds which correspond to the graph above, it can be seen that

when seeds were germinated using fertiliser, growth was fast with the first indication that

growth in fertiliser of coriander would not surpass that of parsley as the first average

measurable value taken at day two was 5.9mm, 0.2mm lower than the average shoot length of

parsley plant at day two. At day three, the shoot grew at a rate of 2.3 times, standing at anaverage height of 14.1mm which was 0.7mm higher than that of the average parsley height at

day three. The Coriander plant continued to surpass the height of parsley every successive

day reaching a maximum of 41.1mm at day seven which was 1.12 times greater than the

parsley plant under the same circumstance.

With reference to the coriander plant grown in hydroponics solution, its growth was similar

than that of its neighbour in fertiliser at the first day at 5.81mm, only 0.9mm lower and this

was expected as at day one and two, fertiliser was used. The measurements taken the very

next day averaged out to be 3.1 times the previous average at 18.53mm. This was the largest

increase and can be clearly seen on the graph as the steepest rise and was also expected asthis was the first measurement in hydroponics solution. The rate of increase decreased the

following day at 1.4 times and this rate of increase was roughly maintained throughout the

experiment to day seven. The average measurement at day five was 33.71mm, an increase at

1.3 times. It was noted that seed number six was noticeably lower than the rest of the seeds

during that day and remained lower than usual even during day six where it brought the

average measurement down to 40.97mm but at day number seven, it had increased to being

the second highest plant in the day seven series. The average measurement taken at this day

was 48.95mm with all plants conforming to a similar height and no anomalies were recorded.

Every recorded average value of coriander in hydroponics solution significantly surpassed theheight of the same seed type in fertiliser, a trend which was also noted whilst growing

parsley.


31/39



Seed

number:

1 0 7.9 19.5 31.3 40.4 49.4 60.1

20 8.3 19.9 32.1 37.9 42.2 52.2

3 0 8.4 20.02 29.9 42.7 49.4 60.4

4 0 8.2 19.9 30.9 41.8 49.2 60.43

5 0 8.1 21.2 29.1 40.9 49.0 63.3

6 Negligible 7.9 20.0 33.9 44.1 51.1 60.11

7 0 7.8 19.7 31.3 42.4 48.4 62.2

8 0 8.6 20.22 32.3 43.4 49.4 63.3

9 0 8.1 19.98 30.9 40.2 49.4 61.2

10 0 7.2 19.84 30.1 40.0 49.0 60.4

Average

Length

(mm)

0 8.05 20.02 31.18 41.38 48.65 63.64

Figure 18, graph

3, showing the

comparison

between the

garlic plants in

two growth

mediums.


32/39


It was noticed immediately at day two that the growth of garlic plants in fertiliser was

somewhat higher than that of its parsley and coriander counterparts measuring at 8mm

compared to 5.9 in coriander and 6.1 in parsley, averaging to a value of 6.0mm. Day three

also presented an average measurement that was above that of the other plant types at this day

which was at 17.7mm, 2.2 times that of the previous day, rising to 27.8mm at day four, 1.5that at day three and kept increasing but at slightly decreasing rates until reaching a

maximum of 50.9mm at day seven which was the highest recorded average value for any

plant shoot across the range of thirty plants used in this trial. It was noted that at the

penultimate day, the measurement of the garlic plant exceeded the value of both parsley and

coriander at day seven. It was important to note that the higher values associated with the

garlic shoots occurred despite the control of variables and so it was accepted that the garlic

plants were generally taller than the parsley and coriander even when the independent

variable was unchanged (growth medium).

As the independent variable was changed to hydroponics solution as opposed to fertiliser, thedependant shoot lengths began to also change. Measurements at day one and two conformed

to the previous values obtained by growth of garlic seeds in fertiliser as was the case here

also but once the plant was immersed in sachs solution after day two, the measurement atday three indicated a slightly higher value than its fertiliser counterpart at 20.02mm. The

measurements taken at day four was 1.3 times this value and indicated a gentle increase

which was also the case for day five where the rate of increase was the same. After this, it can

be seen in the graph that between day five and six, there is a blip and a short period of slowed

growth where the rate of increase was only 1.1 times the previous average measurement. All

measurements on day six were close together with the exception of seed number two which

would have been a reason contributing to the sluggish growth observed which may be due to

a particular factor that was present during the time period between day five and six. The

average measurement at day seven was higher than expected at 63.64mm and can be seen on

the graph as a steep positive correlation. Plant number two again was measured to be

52.2mm, considerably lower than the 63.64mm average and was considered an anomaly but

included in the average calculation.

Evaluation

The results of this experiment are clear and coherent and indicate a definitive correlation. If I

compare day three of both experiments (the day at which the plants were transferred into the

hydroponics solution) growing parsley plants, it can be seen that the percentage increase in

height achieved by the parsley plant grown in hydroponics solution was (16.57-13.4) =3.17,

(3.17/13.4)*100= 23.6% higher than the parsley plant grown in fertiliser. If day four is

compared, the percentage increase of the parsley plant in hydroponics was (24.84-20.80)

=4.04, (4.04/20.80)*100= 19.42% higher than the plant in fertiliser. At day five it was

(32.72-27.3) = 5.42, (5.42/27.3)*100= 19.85% higher, at day six it was (37.8-34.2) = 3.6,

(3.6/34.2)*100= 10.52% higher and at day seven it is (42.6-36.4) = 6.2, (6.2/36.4)*100=17.03% higher.


33/39


If I compare day three of both experiments growing coriander plants, it can be seen that the

percentage increase in height achieved by the coriander plant grown in hydroponics solution

was (18.53-14.1) =4.43, (4.43/14.1)*100= 31.41% higher than the coriander plant grown in

fertiliser. If day four is compared, the percentage increase of the coriander plant in

hydroponics was (26.6-22.0) =4.60, (4.60/22.0)*100= 20.90% higher than the plant infertiliser. At day five it was (33.71-28.4) = 5.31, (5.31/28.4)*100= 18.6% higher, at day six

it was (40.97-35.0) = 5.97, (5.97/35.0)*100= 17.06% higher and at day seven it is (48.95-

41.1) = 7.85, (7.85/41.1)*100= 19.09% higher.

If I compare day three of both experiments growing garlic plants, it can be seen that the

percentage increase in height achieved by the garlic plant grown in hydroponics solution was

(20.02-17.7) =2.32, (2.32/17.7)*100= 13.11% higher than the garlic plant grown in fertiliser.

If day four is compared, the percentage increase of the garlic plant in hydroponics was

(31.18-27.80) =3.38, (3.38/27.80)*100= 12.16% higher than the plant in fertiliser. At day

five it was (41.38-34.8) = 6.58, (6.58/34.8)*100= 18.9% higher, at day six it was (48.65-41.8) = 6.85, (6.85/41.8)*100= 16.4% higher and at day seven it is (63.64-50.9) = 12.74,

(12.74/50.9)*100= 25.02% higher.

Every plant subject to growth via sachs hydroponics surpassed the height of the same planttype which was allowed to continue to grow in fertiliser irrespective of the stage of growth.

The largest increase that was measured was that of the garlic plants at the end of the

experiment which measured an average 63.64mm, a 25.02% increase compared to the garlic

plants left to grow in fertiliser.

It can be concluded that following the germination and growth of a combined total of sixtyseeds, the hydroponics growing technique applied in this circumstance not only benefits plant

growth, but allows the plant to surpass the height achieved by growth in fertiliser by a

substantially noticeable amount and at faster rate between each successive day which is of

paramount importance in industry/farming where it is important to obtain maximum plant

yield in minimum time.

My rationale was to deduce whether hydroponics solution was really effective to increase

plant growth substantially and after hours of planning, growth and write ups it can be shownthat all values conform to suggesting that hydroponics is effective. The values at the end of

the three main experiments show that the parsley plant in hydroponics solution finished at

17.3% taller than its fertiliser counterpart, the coriander plant in hydroponics finished at

19.09% taller than the coriander plants in fertiliser and that the garlic plant grown in sachsstandard was 25.02% taller than the garlic plants left to grow in fertiliser. Not only one plant

shows this correlation but all three indicate a causation to support the conclusion that

hydroponics solution is a more effective growth medium in comparison to fertiliser.

Anomalies were present in the investigation and existed at parsley seed three, day two,

parsley seed seven, day two, parsley seed seven, day three, coriander seed six, day five, garlicseed two, days six and seven. The effect that these values had on the average calculated was


34/39


negligible and only swayed the results marginally below what they should have been if the

experiment was running at 100% efficiency.

Reasons for anomalous values may have ranged from measuring errors which were

minimised by the use of precision equipment, irregular sunlight patterns to which some seeds

may have been more sensitive than others due to genetics, the concept that all seeds are

genetically different and so will grow differently, due to the large period of time where the

plants were left unattended, it is possible that some may have been tampered with, interfering

with the growth process. The fact that a total of ten seeds of each type were grown, the effects

of anomalous values were minimised.

Linking in aspects of the research section allows for the better interpretation for the results in

this experiment. Potassium, phosphorus and nitrogen were present in all growing techniques

and formed the backbone of the constituents of the fertiliser which allowed the basic plant

mechanisms to function such as ionic processes, gaseous exchange, protein synthesis and the

biochemical functions of chlorophyll which allows photosynthesis to occur. When analysing

the data, it can be said that the heights of all plant type when grown in fertiliser are due to

these three elements with the addition of water and sunlight.

Changing the independent variable from fertiliser to sachs hydroponics solution allowed afaction of further elements to be incorporated into the plant physiology such as calcium,

magnesium and sulphur which are the sole difference between the two methods of growing

techniques.

Whilst calcium emphasised a focus on disease reduction, magnesium contributed to factors

such as root formation and photosynthesis which is also a function of nitrogen and may

explain why plants in sachs solution grew to a greater height than in fertiliser as enhancedphotosynthetic mechanisms were in place and exhibited.

Evaluating the economical aspect to hydroponics; high concentration nutrient solutions are

widely available which provide high value for money and are significantly more effective

than fertilisers which can be purchased for similar prices. Not only is this growing process the

most economical method of supplying nutrients to plants, but it also allows users to prevent

the spread of various diseases. Hydroponics frequently includes a higher level of crop yields

than is generally obtainable in normal soil/fertiliser culture, together with faster growth andearlier maturity of fruits, flowers and vegetables. Standard hydroponics methods simplify the

work input which is further emphasised by the elimination of hard manual operations such as

ploughing, digging, weeding and soil sterilisation. The cleanliness intrinsic hydroponics

systems combined with the nonexistence of dirt and smells is also a significant factor that

assists in the maintenance of good phyto-sanitary conditions.


35/39


The variance of Sachs Hydroponics solution:

Sx = x-/nx -x = 4033.53/723.15= 40.296

The variance of Industrial organic fertilizer:

Sy = y/nY - y = 3889.3/719.74= 165.95

The Pooled variance:

2= nx xSx + nY x Sy / nx+ nY2=7 x 40.296 + 7 x 165.95/ 7+72= 120.310Standard deviation:

= 2(Square root of the pooled variance) =120.310 = 10.96Difference between the sample means:

XY = 23.1519.74= 3.41

The T-Test:

(xy) xnx x nY/ xnx+ nY= (3.41 x 7x7) / (10.96 x 7+7)= 0.58Degrees of freedom:

nx+ nY2 = 7+7-2= 12

The Critical value : = 2.179

Day 1 Day2 Day3 Day4 Day5 Day6 Day7 mean

Sachs

Hydroponics

Solution/x

0 6.56 16.57 24.84 32.72 38.01 43.4 23.15

x 0 43.03 274.56 617.02 1070.6 1444.76 1883.56 x

4033.53

Fertiliser/y 0 6.1 13.4 20.8 27.3 34.2 36.4 19.74

y 0 37.21 179.56 432.64 745.29 1169.64 1324.96 y

3889.3

Average length of parsley plants in hydroponics solution. (mm)

Average length of parsley plants in fertiliser.


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Sx = x/nx -x = 6295.67/724.93= 277.87


Sy = y/nY - y = 4438.39/720.92= 196.41


2= nx xSx + nY x Sy / nx+ nY2=7 x 277.87+ 7 x 196.41/ 7+72= 276.66Standard deviation:


XY = 24.9320.92= 4.01

The T-Test:

(xy) xnx x nY/ xnx+ nY= (4.01x 7x7) / (16.63 x 7+7)= 0.451Degrees of freedom:

nx+ nY2 = 7+7-2= 12



Sachs

Hydroponics

Solution/x

0 5.81 18.53 26.6 33.71 40.97 48.95 24.93

x 0 33.75 343.36 707.56 1136.36 1678.54 2396.10 x

6295.67

Fertiliser/ 0 5.9 14.1 22.0 28.4 35.0 41.1 20.92

y 0 34.81 198.81 484 806.56 1225 16892.21 y

4438.39

Average length of coriander plants in hydroponics solution. (mm)

Average length of coriander plants in fertiliser.


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Sx = x/nx -x = 9566.96/730.42= 441.33


Sy = y/nY - y = 6699.22/725.85= 288.80


2= nx xSx + nY x Sy / nx+ nY2=7 x 441.33+ 7 x 288.80/ 7+72= 425.91Standard deviation:


XY = 30.4225.85= 4.57The T-Test:

(xy) xnx x nY/ xnx+ nY= (4.57x 7x7) / (20.63 x 7+7)= 0.414Degrees of freedom:

nx+ nY2 = 7+7-2= 12



Sachs

Hydroponics

Solution

0 8.05 20.02 31.18 41.38 48.65 63.64 30.42

x 0 64.80 400.80 972.2 1712.30 2366.82 4050.04 x

9566.96

Fertiliser 0 8.0 17.7 27.8 34.8 41.8 50.9 25.85

y 0 64 313.29 772.84 1211.04 1747.24 2590.81 y

6699.22

Average length of garlic plants in hydroponics solution. (mm)

Average length of garlic plants in fertiliser.


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The statics test chosen is the unpaired T-test as my independent variables are unpaired. This

means the data in the independent variables are not linked. In this case my independent

variables are the different types of growing techniques so for this reason the unpaired T-test

was used.

Conclusion

Prior to the statistical analysis of the raw data, it was stated that there was a clear trend in the

results of the investigation however post statistical review reveals an interesting predicament.

The critical value was 2.179 (which was established by comparing the degrees of freedom)

which is higher than the T value at the 95% confidence level for all three plant types. This

striking information actually means that the alternate hypothesis is rejected and the null

hypothesis is accepted in its place. Initially this causes confusion as the null hypothesis statesthere will be no difference in plant heights irrespective of the growing technique when this

clearly does not seem the case and initially the alternate hypothesis seemed more appropriate.

The reason for the statistical indication towards the accepting of the null hypothesis arises

from the fact that the increase in plant heights whilst growing them in hydroponics solution

was not significantly large enough for the statistics to incline towards suggesting the alternate

hypothesis. This is emphasised by the difference in sample means (XY = 23.1519.74=3.41 for parsley), (XY = 23.1519.74= 4.01 for coriander) and XY = 23.1519.74= 4.57for garlic). Here it is obvious that the difference between the two growing techniques in

parsley, coriander and garlic plants are not significant and give an average difference of a

mere 3.99mm.

Certain variables were possible to control but the ones that were uncontrollable are those that

caused limitations in the experiment. Such limitations can be identified for example the

amount of light that the plants received over the course of the seven day period was very

much variable. The effect of this was minimised due to the short period of time this

experiment was conducted under in comparison to the yearly season and so reduced the

likelihood of major natural light fluctuation. The replenishing of the hydroponics solution

was potentially a limiting factor as the new solution may have been more or less concentrated

than previous solutions due to a measuring error in the water, sachs powder ratio howeverthis was again minimised due to the use of precision measuring instruments. In relation to theplants in fertiliser, irregular volumes of water during successive watering periods may have

contributed to different measurement values to that which were expected. Room temperature

was known to have varied especially during the night where temperatures may have

plummeted, being another significant limiting factor.

Genetic variation is a key concept which is addressed in many stages of this course and the

sixty different seeds in this investigation are no doubt, potentially very genetically diverse.

This means that all individual seeds have different maximum heights that can be genetically

possibly reached.


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Another limitation which can be easily overlooked is the interpretation ofincreased plant

growth. Surely, this seems straightforward enough however there is discrepancy in saying

that increased plant growth strictly means the height of plant. Increased plant growth may

refer to increased root formation, stem formation, amount of leaves present, thickness of

stem, mass of leaves, surface area of leaves or dry mass of plant.

It is possible that the hydroponics solution actually did significantly cause greater growth in

the plants which were grown in it but was expressed not in height, but may have caused the

plant to grow a larger amount of leaves or be wider or weigh more than the plants grown

using fertiliser.

For the purpose of this investigation, the height of plants was chosen to determine plant

growth as it is the easiest value to measure, quantify and the generally accepted way to

measure plant growth however the fact that the other methods of measurement were ignored,this remains the most significant limitation to the main experiment.

Future Experiment.

Due to excess limitations, this experiment lacked ecological validity as it was carried out in a

laboratory and ultimately failed to prove that hydroponics substantially benefits plant growth.

If this experiment were to be recreated in the future, it is essential that it is carried out in an

environment which represents natural habitat or one similar to industry where yield

maximisation is the main priority. Perhaps a larger variety of plant seed types would have

lead to data that would support the alternate hypothesis and so this should be considered. Anenvironment where temperature is constantly monitored such as a greenhouse would be the

preferable location for all trials and main investigations to occur and an increase in the

amount of seeds experimented on would be beneficial. A review over which hydroponics

solution to use with cross comparisons between all available nutrient solutions should be

considered and the ratio when preparing solutions should be investigated thoroughly to make

certain that the optimum mixture is produced ensuring that the null hypothesis is never

accepted again.

Documents

Determining whether hydroponics provides a benefit in plant growth in comparison to fertiliser