Strategies for mitigation of impact of climate change on subtropical

fruits 

Dr. Parshant BakshiAssociate Professor

Division of Fruit ScienceFOA, SKUAST-J, Chatha - Jammu

02 days SAMETI training on Climate resilient fruit Production Technologies w.e.f. 1st-2nd December, 2015

Evidences have shown that human activities are changing

the climate. The main human influence on global climate is

likely to be emission of green house gasses (GSG) such as

carbon dioxide (CO2) and methane (CH4). The global

increase in carbon dioxide concentration are due primarily

to fossil fuel use and land use change, while those of

methane and nitrous oxide are primarily due to agriculture.

Climate Change

Climatic element Expected changes by 2050's

Confidence in

prediction

Impact on horticulture

CO2

Increase from 360ppm to 450 – 600 ppm (2005 levels now at 379ppm)

Very highGood for crops: increasedphotosynthesis; reduced water use

Sea level rise

Rise by 10 -15 cm. Increased in south and offset in north by natural subsistence/rebound 

Very highLoss of land, coastal erosion, flooding, Salinization of groundwater

Tempera ture

Rise by 1-2oC. Winters warming more than summers. Increased frequency of heat waves

High

Faster, shorter, earlier growing seasons, range moving north and to higher altitudes, heat stress risk, increased Evapo transpiration

Precipita tion Seasonal changes by ± 10% Low

Impacts on drought risk' soil workability, water logging irrigation supply, transpiration

StorminessIncreased wind speeds, especially in north. More intense rainfall events.

Very low Lodging, soil erosion, reduced

infiltration of rainfall

Predicted effects of climate change over the next 50 years

How this changing climate effect fruit crops Temperature

Higher temperature speed plant growth and development in annual crops

In perennial crop, being grown in a climate near its optimum, a temperature increase of several degrees could reduce photosynthesis and shorten the growing period affecting the productivity e.g. banana.

In areas where current temperatures are below optimal for specific crops, there will be a benefit, while in areas where plants are near the top of their optimal range, yields will decrease .

Even a minor climate shift of 1-2o C could have a substantial impact on the geographic range of these crops. As fruit crops are perennial moving production area is difficult.

How this changing climate effect fruit crops Carbon dioxide

It is accepted that the atmospheric CO2 is increasing exponentially and will likely to double i.e. about 700 ppm within the next century .

This has a beneficial effect on plants and increase productivity.

This is not universal as the biochemistry of photosynthesis differ among plant spices.

C3 plants benefit much more from increase in CO2 than C4.

Build up of sugar in the leaves giving a negative feed back on photosynthesis and benefits from elevated CO2 become minimal.

How this changing climate effect fruit crops Precipitation Rainfall • Change to India's annual monsoon are expected to result in severe droughts and intense flooding in parts of India.•This change create problems for field operation, more compaction of soil, and possible crop losses due to lack of oxygen for roots and disease problems associated with wet condition.•Trend over the decreased amounts of annual rainfall in Kullu valley- the attribute on which the colour of an apple mostly depends and regulation of moisture stress.

Snowfall• On set of early snow in December and January had occurred more infrequently overtime and extended through the months of Feb. and March.

• Early snow contributes nitrogen for plant use, replenish soil moisture and prevent humidity build up.

• Amount of snow determines the number of chilling hours and thereby the time of bud break

A significant change in climate at global and national level is certainly impacting our fruit production and quality.

But understanding of impact of climate change on perennial horticultural production system and the potential effects on fruit quality have drawn a little attention of researchers.

The consequences of such rapid change are - global warming, change of seasonal pattern, excessive rain, melting of ice cap, flood, rising sea level, drought etc. leading to extremity of all kinds.

Decrease in potential yields is likely to be caused by shortening of the growing period, decrease in water availability.

High humidity (85-90%), moderate temperatures (maximum temperature of 25-26°C and minimum of 18-20°C) provided favourable condition for the initiation of disease (Chhata et al., 2006).

Intr

oduc

tion

Climate change effects

on Subtropical

fruits

FRUIT LEAF

Impact of climate on subtropical fruitsSu

nbur

n in

Citr

us

Citrus fruit plants are considered to be better equipped to deal with a changing climate than other fruit crops. That's largely because they flourish in the heat. Lemon cultivation area will shrink by around 10 percent, that is a small setback in comparison to other plant. Citrus greening, for example, is a bacterial disease that is primarily spread by two types of psyllid insects. It turns a citrus plant's leaves and shoots yellow and makes the fruit bitter, often cause the wither away of entire plant. But in different case in District Kangra, Himachal Pradesh, citrus fruit production has declined by 1,000 tonnes in the district in the last two years. "In 2009-10, it was 22,184 tonnes while in 2010-11 it decreased to 21,704 tonnes," district horticulture authorities said. "Climate change is one major factor affecting the fruit crop. We are facing problems on this count for the last eight to ten years. It's not raining in time because of which, plants are not getting proper nutrition and fruiting is declining gradually.

High temperature and high evaporation during flowering and fruit set result in low yield due to flower and fruit drop. The fruits have poor colour if the temperature during fruit maturation is high. In Navel oranges the content of acidity was affected by low temperature leading to low TSS content.

Among other climatic factors the rainfall in September and October had an obvious effect on the fruit soluble solids content where less rainfall in this period increased the soluble solids

Citrus

G

rape

s Frost and Drought stress

Grapevines are damaged by frost if it occurs during their active growth but resting vines during winter are not affected in north and central India. However, in peninsular India, where occasional frost is expected during winter, there is adverse affect on the growing vines.

Similarly, high temperature above 115°F causes thick skin of berries. Rainfall quantity and duration and season influence discernible. Rainfall during flowering and fruiting is detrimental.

Increased humidity due to prolonged rainfall makes fruits tasteless and there is skin cracking.

High night temperature reduces anthocyanin accumulation in berry skin which is due to low expression of anthocyanin biosynthesizing genes and enzymes.

Reduced number of berries per cluster due to high root temperatures (seen in Cabernet Sauvignon).  The soil temperature recorded so far in August at Perkins has averaged 96 F (bare soil), with readings as high as 106 F.

Earlier fruit maturation (short term conditions).

Delayed fruit maturation and a reduction in fruit quality (excessive and long term conditions).

Decline in total TA and increased pH through loss of malic acid.

Increased mono and di-basic salts of tartaric acid.

Reduced color development (anthocyanins) in red berries.

Reduction in gas exchange capacity (although this is influenced by vapor pressure deficit).

Potential elimination or reduction of virus with long term exposure (>30 days).

Reduction of leaf starch content.

Reallocation of photosynthates, going to shoot tips at expense of roots, trunks, and clusters.

Increase in sucrose concentrations in all vine organs.

Decreased glucose and fructose concentrations in fruit (observed in Chardonnay).

Man

goPsuedo-fruit setting in mango.Frost affected mango plant

High humidity, rainfall and frost during flowering are harmful.

Water stress is known to increase the fruit drop in mango.

Mango phenology is highly influenced by variations in temperature. like most of tropical and sub-tropical trees fruit crops, mango has a vegetative bias, which becomes stronger with increasing temperature.

Early flowering under the subtropics may result in low fruit-set because of abnormalities arising from prevailing low night temperatures.

High temperature by itself is not so injurious to mango, but in combination with low humidity and high winds affects the growth of the trees adversely.

The distribution of rainfall is more important than quantity of the rainfall.

A dry weather before blossoming is conducive for profuse flowering.

Higher temperature during fruit development hasten fruit maturity and improve fruit size and quality. However , prolonged exposure of fruits at time at near maturity to the summer sun when temperatures exceed 350C

may cause sun burning.

Localities which receive bright sunny days and a relatively low humidity during flowering period are ideal for mango cultivation.

the current equation: high temperature + low soil moisture + high evaporative demand = low yield (Schaffer et al 2009)

Red colour development on the peel of guava requires cool nights during fruit maturation. Varieties like Apple Colour, which have attractive apple skin colour under sub-tropical conditions of North India, have red spots on the skin under tropical South Indian conditions. An increase of 0.2°C in temperature resulted into dramatic reduction in the areas suitable for development of red colour in guava; an increase of 0.5°C in temperature will reduce the areas drastically with the suitability probability of more than 97% to a very low level. Based on a future climate database, predictions show that areas with suitability percentage of less than 70% will be available for red colour guava development. Areas suitable for red colored guava cultivation will be reduced dramatically because the minimum temperature during the coldest month may increase up to 1.9oC, whereas, the mean temperature of the coldest quarter will be 3.2oC higher than the existing temperature resulting in less red colour development in guava fruits.

Guava

Effect of climatic variables on flowering and fruit set

Variable Expectedchange

Expected effect onflowering and fruit set

Temperature increase Negative effect on floral induction

Positive effect on pollen viability, fruit set.

Light increase Positive effect on growth.

VPD increase Negative effect on growth

Drought increase + (floral induction indirectly) - (fruit set and retention)

Litchi

Litchi is essentially a sub-tropical fruit which require protection from frost free winter and dry hot summer. The young plants of litchi require protection from frost and hot desiccating winds otherwise their growth and survival is affected. Bearing litchi trees are affected by hot winds causing fruit skin cracking and sun bum.The observed temperature trends in the region of litchi production (Bihar) showed a general increase in temperature in order of 2-3oC overt the base period of 50 years. The unusual impact of climate change has been witnessed in litchi production system as noted in flowering pattern (shifted early), fruit growth and harvesting periods. The occurrence and the extent of damage by physiological disorders and resurgence of pest are very much dependent on the temperature and humidity variations in the atmosphere.

Ber can be successfully grown under varying climatic conditions but temperature below freezing is injurious to fruits as well as young plants.

In papaya, higher temperatures have resulted in flower drops in female and hermaphrodite plants as well sex changes in hermaphrodite and male plants. The promotion of stigma and stamen sterility in papaya is mainly because of higher temperatures.

Ber

Papaya

Low chilling fruits

LC fruits being cultivated in sub-tropics are also under the threat due to

non-availability of required chilling hours which has adverse effect on

their flowering and the abrupt rise in temperature after fruit set is

causing excessive fruit drop as well as there is poor sugar accumulation

in the fruit due to steep rise in temperature during fruit development.

Fruit that are exposed to high sunlight and high temperature conditions near

harvest may experience sunburn to the skin that can cause cracking. 

Severely stressed, because of high temperature and insufficient rainfall, premature fruit drop may occur in peach. 

Climate change will impact fruit industry and region

• Changes in the suitability and adaptability of current cultivars as temperatures change, together with changes in the optimum growing periods and locations for fruit crops. For instance, in pomegranate, the aril colour turns from red to pink. However, it is the genotype x environment interaction that ultimately decides the expression of a trait. The stability of the genotype to perform under different environment is the ultimate deciding factor in the expression of any trait.

• Changes in the distribution of existing pests, diseases and weeds, and an increased threat of new incursion.

• Increased incidence of physiological disorders such as tip burn and blossom end rot.

• Greater potential for downgrading product quality e.g. because of increased incidence of sunburn.

•Increases in pollination failures if heat stress days occur during flowering.

• Increased risk of spread and proliferation of soil borne diseases as a result of more intense rainfall events coupled with warmer temperatures.

•Increased irrigation demand especially during dry periods.

•Changing reliability of irrigation schemes, through impacts on recharge of surface and groundwater storages.

• Increased atmospheric CO2 concentrations will benefit productivity of most fruit crops, although the extent of this benefit is unknown.

• Increased risk of soil erosion and off-farm effects of nutrients and pesticides, from extreme rainfall events.

• Increased input costs-especially fuel, fertilizers and pesticides.

STRATEGIES FOR MITIGATING EFFECT OF CLIMATE CHANGE

ON SUB-TROPICAL FRUIT CROPS

Pheno-typing of all important fruits genetic wealth to enhancing temperature, moisture stress and genetic enhancement for tolerance to biotic and abiotic stress.

Varieties and rootstocks will be evaluated under controlled temperate moisture stress etc. gradient to identify suitable cultivars of all major fruit crops. Experiments on varietal evaluation will also be conducted under natural conditions at different altitudes/conditions with natural variations in temperature and moisture falling under various agro-climatic zones of the countries.

Marker assisted selection and development of transgenic having resistance to biotic and abiotic resistance.

Development of genotypes having resistance to heat and drought.

I. Breeding strategies

• Assessment of the vulnerability and climate risks associated with tropical and subtropical fruit production in sub-tropical region.

• Development of cropping systems under various agro-climatic conditions.

• Improvement in the irrigation and drainage systems.

• Development of appropriate tillage and intercultural operations.

• Integrated nutrient management.

• Integrated pest management.

• Integrated weed management.

• Development of water harvesting techniques.

II. Agronomic management strategies

•Agri-silvicultural system.

•Agri-horticulture system (Custard apple and also pomegranate and amla are other fruit crops suitable for this system).

•Agri-horti-silvicultural system.

•Horti-pastoral: (aonla based hortipastoral system).

•Inter cropping annual crops under fruit trees.

•Integrated Farming system.

III. Horticulture/Fruit based cropping system

Molecular characterization for various traits in relations to biotic and abiotic stress.

Transformation of plants from C3 to C4 plants.

Gene pyramiding against biotic and abiotic stress.

Engineering for herbicide resistance.

Engineering for disease resistance.

Engineering for insect-pest resistance.

Engineering for improving post-harvest traits.

In vitro conservation of rare and useful species for future use.

IV. Biotechnological innovative strategies

-Mitigation strategies for higher CO2/GHG

• Assessment the carbon sequestration potential of perennial fruit crops production system.

• To participate in the international dialogue about greenhouse gas emissions management, global warming and sustainable energy development.

• The improvements in the efficiency of electricity generation, transmission and distribution.

• The use of fuels with lower carbon content, e.g., natural gas, CNG, Gobber gas.

• Fuel switching, appliance efficiency and use of renewable energy.

• Tree planting and forest management.

• Waste processing.

FUTURE RESEARCH STRATEGIES FOR OPTIMIZING

PRODUCTION UNDER CHANGING CLIMATE SCENARIO

• Utilizing the current and future regional climatic scenarios of the tropical, subtropical and temperate region a micro-level survey of agro-climatic zones of country should be conducted to identify sensitive regions with high vulnerability with respect to different fruit crop. Evaluation of wild species should be probed thoroughly, which could be a source of resistant genes for tying over adversaries of the temperature.

• Evaluation of local types and landraces should be carried out to locate useful genotypes.

• Development of stable genotypes, which can perform across different environments within the region, is needed. There is a need to develop and test the performance of different genotypes across several environments so that their suitability can be judged.

• Development or location of rootstocks that can tolerate biotic stresses induced by temperature regimes is needed. In many crops, rootstocks have helped in combating the biotic stress induced by varying temperature conditions.

I. Crop improvement strategies

•Diversification with other high value fruit crops like peach, apricot, walnut, kiwi and olive.

• Development of new genotypes having resistance to high temperature and CO2 concentrations.

• Marker assisted selection and development of transgenic having resistance to biotic and abiotic resistance.

• Development of genotypes having resistance to heat and drought.

• Biotechnological approaches for multiple stress tolerance will be standardized.

• Introduction of low chilling cultivars of pome, stone and nut fruits.

• Adoption of improved agro-techniques like mulching and cover crops in orchards will help in bringing down the orchard temperature.

• Use of precision farming methods within the orchard thereby reducing the temperature and providing an ideal microclimate.

• Sensitive stages of crops to weather aberrations will be identified.

• The phenology of all major fruit crops under changing climate will be monitored. • In-situ soil moisture conservation practices including indigenous technical know-how will be validated to mitigate the impact of drought. For ex situ conservation, fruit trees present a unique challenge because, unlike cereals and legumes, fruit trees may not have seeds or seeds may be recalcitrant or the varieties may need to be vegetatively propagated. Hence a feasible method for conserving fruit trees ex situ is in field gene-banks.

II. Development of agro-techniques

• Development of suitable agronomic adaptation measures for reducing the adverse climate related production losses.

• Study the impact of climate change and development of technologies on water productivity .

• Identify and develop good practices to enhance the adaptation of crop to increased temperature, moisture and nutritional stress.

• Identification and mapping of climate resilient as well as climatically vulnerable micro-niches in all fruit growing regions.

• Extreme events, such as late spring frost or windstorm, may cause crop failure. Future climate may also increase occurrence of extreme impacts on crops, e.g. weather conditions resulting in substantial reduction in yield and quality (for example severe drought or prolonged soil wetness).

• To develop a set of high resolution daily based climate change scenarios, suitable for analysis of agricultural extreme events.

• To identify climatic thresholds having severe impacts on yield, quality and environment for representative crops and to assess the risks that these thresholds will be exceeded under climate change

III. Plant protection strategies •Assessment of the pest and disease dynamics, study of disease triangle and development of prediction models. • Strengthen surveillance of pest and diseases.

• Development of eco-friendly pest-ecologies and management strategies and early warning systems.

IV. Post-harvest management strategies Development of cost effective storage techniques. Infrastructure like cold storages, refrigerated vans is extremely important to reduce transportation losses. Hence, adoption of cold chain management as well as emerging new technology for preservation of fruit and vegetables with changing environmental conditions.

Development of varieties having longer shelf life. Technologies need to be refined to increase storage life of sub-tropical fruits like mango, papaya and banana etc.

Studies on mitigation of postharvest spoilage and simulation models need to be developed for forecast of field diseases and spoilage under post- harvest loses.

V. HRD & creating awareness

• Organize seminars/ symposia/ trainings and conduct field demonstrations, on effective climate resilient technologies.

The effects of climate change on horticulture sector are still uncertain. Research is needed to define the current limits to these resistances and the feasibility of manipulation through modern genetic techniques. Both crop architecture and physiology may be genetically altered to adapt to warmer environmental conditions.

At the regional level, those charged with planning for resource allocation, including land, water, and horticulture development should take climate change into account.

The continuation of current and new initiatives to research potential minimize the effects of climate change at farm, regional, national and international level and will help to provide a more detailed picture of how world horticulture and agriculture could change.

Only then may we see the implementation of policies and other adaptations in agricultural systems that would minimize the negative effects of climate change and exploit the beneficial effects.

Conclusion

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