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For Review OnlyGrowth and vegetable yield of Amaranthus hybridus L. as impacted by harvest methods in southern Ontario, Canada
Journal: Canadian Journal of Plant Science
Manuscript ID CJPS-2019-0106.R2
Manuscript Type: Article
Date Submitted by the Author: 15-Nov-2019
Complete List of Authors: Farintosh, Geoff; University of Guelph, Plant AgricultureRiddle, Rachel; University of Guelph Simcoe Station, Plant Agriculture; University of GuelphVan Acker, Rene; University of Guelph, Plant Agriculture
Keywords: Edible amaranth, callaloo
Is the invited manuscript for consideration in a Special
Issue?:Not applicable (regular submission)
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Growth and vegetable yield of Amaranthus hybridus L. as impacted by harvest
methods in southern Ontario, Canada
Geoff Farintosh1, Rachel Riddle2 and Rene Van Acker1
1University of Guelph, 50 Stone Road East, Guelph, ON N1G 2W1
2University of Guelph, Simcoe Research Station, 1283 Blueline Rd, Simcoe, ON, Canada N3Y
4N5
Amaranthus hybridus L. is a nutritious leafy vegetable amaranth species grown primarily in
tropical regions. Weedy amaranth species thriving in southern Ontario suggest the edible biotype
could also grow efficiently as a crop. Field trials in Guelph, Simcoe, and Stouffville, Ontario
examined yield in response to three harvest frequencies (weekly, every two weeks, and every
three weeks) cut at 15 cm above ground level, two traditional harvest practices (Afro-Caribbean
and European) cut every two weeks, and a control which was not cut until the final harvest. The
highest marketable yields and quality measures were observed in plants cut every two weeks,
every three weeks, and using the Afro-Caribbean cutting technique which selects and harvests
thicker stems while leaving new shoots for later harvests. The difference in growth among sites
suggests plants prefer warm, well-drained soil. Marketable yield was as high as 4.02±0.340 kg m-
2 in Simcoe with an average yield across all three sites of 2.37±0.229 kg m-2. This demonstrates
that A. hybridus has the potential to be grown as a vegetable crop in southern Ontario and that
marketable yield can be optimized by method of harvest.
Key words: Edible amaranth, callaloo
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Introduction
Amaranthus hybridus L. is a leafy vegetable amaranth that can be found on every
continent with the exception of Antarctica (Sauer 1967). A. hybridus is generally considered a
weed in North America, commonly known as smooth amaranth, but the leaves and stems are
consumed as a staple food in other areas of the world such as Africa, Asia, the Caribbean and
part of Europe (Abbasi et al. 2013; Schwerzel 1986). With an increasing immigrant population in
Canada, the demand for A. hybridus has grown (Filson and Adekulne 2017). This demand,
coupled with the ability of A. hybridus to grow quickly and its high nutrient content (Akubugwo
et al. 2007), make it a strong candidate for a new crop in southern Ontario (Filson and Adekulne
2017).
Edible vegetable amaranth is harvested differently in different parts of the world based on
climate or customer cultural preferences. In southern Ontario there has yet to be a comparison of
different cutting methods and their impact on marketable yield. Harvesting too frequently may
hinder the plant from re-growing, while waiting for a prolonged period might affect quality if the
harvested product is too tough or stringy for consumers (Materechera et al. 2006). In addition to
harvest timing, the height of the cut is also likely to impact marketable yield. While some
consumers may value the tender growing tips, only cutting them will probably limit yield, while
cutting the entire stem may boost yield but be less desirable to the consumer.
The primary objective of this study was to evaluate which harvest techniques are the most
effective at optimizing both yield and quality of A. hybridus in southern Ontario. These results
may increase the potential to grow more vegetable amaranth in southern Ontario, and be used in
further studies on this crop.
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Materials and Methods
Field experiments were conducted in 2017 at three different field sites: the Guelph Centre
for Urban Organic Farming (Guelph) located at the University of Guelph, in Guelph, Canada
(43° 32’N, 80° 13’W), the Simcoe Research Station (Simcoe) in Simcoe, Canada (42° 51’N, 80°
16’W) and at Farintosh Farms (Stouffville) in Stouffville, Canada (43° 56’N, 79° 21’W). Soil
samples were taken from all three sites using a metal soil corer to a depth of 8 cm. The plot at
Guelph was a loam soil classified as a Luvisol had a pH of 7.6 and had organic matter of 5.2%,
the sample from Simcoe was a very fine sandy loam (VFSL) known as Watford and had a pH of
7.4 and 2.0% organic matter, while Stouffville was a Bookton sandy loam with a pH of 6.3 and
2.7% organic matter (Table 1).
The Simcoe site was planted to rye (Secale cereale L.) in the fall of 2016 and glyphosate
(Roundup Transorb (isopropylamine salt), 360 g a.e. L-1) was applied at 720 g a.e. ha-1 on 9 May
2017. The field was then cultivated on 31 May and 700 kg ha-1 of 15.7-7.2-11.4 (NPK) fertilizer
was applied. Prior to planting the land was worked again to incorporate the fertilizer and bury
emerging weeds. The Stouffville site was planted with edible amaranth in 2016 and ploughed in
the fall, 550 kg ha-1 of 6-24-24 was applied and the soil was cultivated three times before
planting. The Guelph site was covered primarily in orchard grass (Dactylis glomerata L.) before
it was rototilled and raked by hand before planting.
There were six treatments in total and four blocks (replicates) at each site with the
exception of Guelph where there was only room for three blocks (replicates). Three harvest
treatments were cut to 15 cm above ground at three different timing intervals: weekly, every two
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weeks, and every three weeks. In addition to these three treatments, two harvest treatments were
included to mimic the two most common consumer self-harvesting approaches (pick your own).
First, Afro-Caribbean consumers tend to desire the plants to be cut low, where the side shoots
meet the main stem, selecting thicker, more mature stalks. Other consumers, including those of
European descent, prefer to take the very tips of each stalk. Both of these “consumer” treatments
were applied every two weeks. Finally, a control treatment was included where the plants were
not harvested until the final harvest date. Field plots were arranged in a randomized complete
block design.
Seeds were planted into 128 cell trays in Stouffville on 26 April 2017 and placed in a
greenhouse to encourage seed germination and the establishment of seedlings. Approximately
eight seeds were planted into each 28.6 mm2 cell. As the seeds emerged and the seedlings grew,
they were thinned to five seedlings per cell. Once the seedlings were approximately 10 cm in
height they were transplanted into the field sites. The A. hybridus seedlings were transplanted at
the Simcoe, Guelph, and Stouffville sites on 9, 12 and 13 June 2017 respectively. At the Simcoe
and Stouffville sites each transplant was planted with roughly 250 mL of 8.5g L-1 20-20-20
(NPK) synthetic liquid fertilizer while at Guelph the transplants were planted with 250 mL of
water due to the organic certification of the site. Transplants were planted with 45 cm spacing in
the row, with the rows 1 m apart. In early July, 85 kg ha-1 of 46-0-0 fertilizer was applied at the
Simcoe and Stouffville sites whereas the Guelph site received no fertilizer. Once the plants were
roughly 30 cm tall, all six treatments were cut to a height of 15 cm in early July to encourage
adventitious growth. When plants grew back to 30 cm tall the initial harvest began. The plants at
the Guelph site grew much slower, likely due to no fertilizer application, so the harvest began
three weeks after Simcoe and Stouffville, when the plants were only 20 cm in height. Each plot
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comprised of three rows with five plants in each row, for a total of 15 plants per plot. For harvest
measurements and analyses, only the three middle plants from the center row were sampled.
Plants were harvested by cutting perpendicular to stems using a sharp knife. Cuttings
from the middle three plants in each plot were pooled for a given plot. Fresh weights were
immediately measured on site using an ADAM®CPW plus -15 scale (Adam Equipment Inc.,
Fox Hollow Road, Oxford, CT, USA, 06478) with a precision of 5 g and a max weight of 15 kg.
Once fresh weights were measured, samples were put in a paper bag, labeled, and moved to a
dryer. The dryer maintained a temperature of 48.9 °C. After two weeks in the dryer, the dry
weight was measured using the same scale. Weight measurements were converted to kg m-2.
Statistical analysis software (SAS) version 9.4 (SAS Institute, Cary, NC) was used for all
statistical data analysis. An analysis of variance (ANOVA) for mixed models was carried out
using PROC GLIMMIX. The different harvest treatments were the fixed effects, while block was
the random effect. There was a significant interaction between site location and harvest treatment
thus data for each location was analyzed separately. The data was tested for normality using the
Shapiro-Wilk test and Q-Q plots generated by PROC UNIVARIATE. The PDMIX800 macro on
SAS was used in combination with Tukey’s test to convert Fisher's LSD means separation into
letter groupings. All analyses were considered significant at α=0.05.
While data were collected for a total of eight weeks (initial harvest, six weeks of harvest
with treatments applied, and a final harvest where plants were cut to ground level) to best display
results, the data were placed into three groupings to make relevant comparisons. These groupings
were:
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A. Regrowth: Contains only harvest data from the six weeks after the initial harvest. These
data are most representative of the treatments as they do not contain the initial harvest
before the treatments were implemented and because the treatments that were harvested
weekly, every other week, and every three weeks all fall naturally on the sixth week
without harvesting any trial prematurely.
B. Marketable yield: Contains the harvest data from the six weeks in addition to the initial
harvest. The final harvest was not included in this group as the plants were cut down to
ground level and much of the biomass would not be close to the quality expected by
consumers. This grouping provides the most accurate estimate of marketable yield from a
seven week period.
C. Total Biomass: Contains initial harvest, the six week treatments where applied and the
final harvest where plants were cut down to ground level. With so much focus on what is
being harvested it is important to also have a final harvest to account for all plant growth
during the experiment period. By combining all the harvest data together it is easier to
understand how the treatments affected the biomass production of this species under
these conditions.
Results and Discussion
These groups were presented individually for each site as there were significant
differences between the three sites (P =
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was certified organic and thus no synthetic fertilizer could be used which could have an effect on
plant growth. Another reason that the Guelph site may have been behind in plant growth was due
to a wet start to the growing season. There were 244 mm of rain in June and July in Guelph,
when Stouffville and Simcoe had only 136 mm and 102 mm, respectively, during the same
period (Table 2). There was no supplemental irrigation at any of the sites. Guelph was also not as
warm as the other two sites throughout the course of the experiment (Table 2). The differences in
yield between Guelph and Stouffville are harder to assign to monthly temperature and
precipitation differences or differences in soil fertility. Rather, the timing of rainfall may have
been a factor, especially in June in which Stouffville received heavy rain early in the month. In
Simcoe rainfall was more even throughout the month of June. These differences in weather
seemed to have affected yield greatly over the course of the experiment. While the first harvest
was done at the same time across all three sites, the plants were already very different in size
between sites and may have responded differently to treatments that did not account for plant
size at time of application.
Regrowth
Analysis of plants harvested at the Stouffville site showed significant fresh weight
differences among all five harvest treatments (Table 3). From highest to lowest yield, the
treatments ranked as; the customer method of selecting for large stems and cutting low, then
triweekly, biweekly, weekly, and lastly harvesting only the tips. Dry weight measurements
followed the same treatment order, with significant differences between some treatments with
respect to dry weights (Table 3). Like fresh weight, for dry weight, the customer treatment was
significantly higher than other treatments, while the tips only treatment was not significantly
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different from the weekly harvest treatment. The ratio of fresh to dry weight was greatest for the
triweekly treatment, closely followed by the customer treatment. These two treatments both
allowed the plant to grow longer and achieve thicker stems, suggesting that the stems may be
able to contain more water as a percent than the leaves.
At Simcoe the results followed a similar pattern to the Stouffville site, with customer and
triweekly treatments providing the greatest fresh and dry weights (Table 3). The results at the
Simcoe site for the tip only treatment also mirrored the results Stouffville with significantly
lower fresh and dry weight versus the other treatments. Only the fresh to dry weight ratio of the
customer treatment was significantly higher than the tip only treatment. For the Simcoe site, the
ratios were higher in general compared to the Stouffville site. This was surprising considering
Stouffville received 62 mm more rain in July and August than did Simcoe. Neither site was
irrigated but the Simcoe site received rainfall more regularly, while the Stouffville site had only a
few high-rainfall events (Table 2).
The Guelph site had very few significant differences among treatments. The dry weight
of the weekly treatment was significantly higher than the tips only treatment, the biweekly and
the triweekly treatments. The ratio of the tips only treatment was significantly higher than the
weekly cutting treatment (Table 3). The fresh and dry weights from this site were low compared
to the other sites and there was greater variation around the means. This meant that even in cases
where the means between treatments were numerically great (e.g. fresh weight for the customer
treatment was more than triple the other treatments) the differences were not statistically
significant. In addition, the mean separation power was lower for this site than the other two sites
because there were only three and not four replicates. As well, the site environment was not
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consistent in multiple directions with a large greenhouse to the south and a waterway to the
north. The low yields for this site were likely due to multiple factors but the key factor may have
been the lack of soil nitrogen because the site was certified organic and thus no synthetic
fertilizer was applied. Ideally, a comparable organic fertilizer would have been used to help
remove some variability from the results.
Across all three sites, the customer harvest treatment tended to provide the highest fresh
weight yield, closely followed by the triweekly treatment. This result is valuable not just because
it highlights how to maximize yield through harvest approach but also because two very different
harvest approaches provided similar results. The customer method is very time consuming as
each stem has to be evaluated and cut individually based on thickness, while the triweekly
cutting method is very time efficient with just a single swipe of the knife required for harvesting
plants every three weeks. The tips only treatment tended to provide the lowest fresh weight yield.
One of the more obvious reasons for this is that such a small part of the plant is being harvested.
The fresh weight yield from the weekly treatment tended to be close to the tips only treatment,
suggesting that two weeks was too long of a harvest interval for the tips only treatment or that
the weekly cuttings allowed the plants to sprout more adventitious growth. A study by Mager et
al. (2006) aimed at reducing plant weight via physical removal of the apical shoot highlighted the
ability of amaranth to produce adventitious growth efficiently. The results showed that when
common waterhemp, Amaranthus tuberculatus L., shoots were removed at a plant height of 10
or 20 cm tall, there was no reduction in weight compared to control plants six weeks after
removal (Mager et al. 2006).
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Marketable Yield
The marketable yield results were very similar to the regrowth results given that the only
difference between these groups was the addition of the initial harvest. Before the initial harvest
approximately the same amount of biomass was present on each plant. By adding the somewhat
constant initial harvest to each treatment the differences were greatly reduced compared to the
regrowth results. Notable from the marketable yield results was how much the initial harvest
differed between sites. The Simcoe site had the largest initial harvest, averaging 1.97 kg m-2,
Guelph had the smallest with 0.28 kg m-2, and Stouffville was in the middle with 0.89 kg m-2. It
is important to highlight these initial harvest weights given that plant size at initial harvest
impacts the extent to which the plant is able to branch and regrow (Harper 1977). For example,
at the Simcoe and Stouffville sites, the initial harvest 15 cm above ground level was relatively
low in relation to the height of the plant, falling just above the first break in the stem. This could
promote growth of new shoots and higher yield. This was not the case at the Guelph site,
however, given that the plants were quite small at first harvest and the cut at 15 cm was near the
top of most plants. At this site, therefore, this initial harvest would have been similar to a tips
only treatment which does not necessarily promote as much branching. It may have been better
to make the initial cut timing based on a physiological stage, and the cut height at a percent of
the plant’s total height to avoid the site differences compounding other variables.
Generally, the results for marketable yield were similar to the results for regrowth, with
the customer and triweekly treatments generating the greatest fresh weights at all three sites,
however, this difference among treatments was only significant for the Stouffville site (Table 4).
The tips only treatment also generally produced the lowest fresh and dry weights but in the case
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of marketable yield versus regrowth, the differences from other treatments were smaller. There
were less significant differences between treatments for the ratios as well, with most significant
differences coming from a lower ratio for the tips only treatment at the Stouffville and Simcoe
sites. By adding the first harvest the effect of the treatments on the ratio between fresh and dry
weight becomes less significant.
The marketable yield and regrowth results provided yield measures from only a relatively
short seven-week harvest season. These results did not include the final harvest which
represented further harvest potential in an open fall season.
Total Biomass
The total biomass results were very different compared to the regrowth and marketable
yield results. The control treatment produced significantly more fresh weight than any of the
other treatments in Stouffville, but this was not the case at the other two sites where none of the
six treatments were significantly different from one another (Table 5). The tips only treatment
was no longer the lowest yielding treatment but one of the highest yielding because while the
small growing tips were being harvested regularly the plant continued to grow thicker, longer
stems and produce reproductive structures. When it comes to edible amaranth though, yield is
only valuable if quality is acceptable for the consumer, and for the total biomass results, the
control and tips only treatments contained very little quality yield (tender leaves and stems) as a
proportion of the total biomass harvested (personal observation). However, the measure of total
biomass allowed us to explore whether the ratio between fresh and dry weight was an effective
measure of quality. This was highlighted when applying the ratio to extreme examples, such as
the control treatment where the plant material was far too tough to be acceptable to consumers.
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While the control treatment had one of the lowest ratios at the Simcoe and Guelph sites, it had
the highest ratio in Stouffville. This difference between sites showed that the ratio was
determined not just by the treatment but also by site factors such as rainfall and soil fertility. The
best measure of quality was a simple visual inspection, making sure leaves were not wilting and
that stems were tender rather than tough.
The total biomass results are important across all three sites because they show that A.
hybridus will produce just as much or more biomass when left untouched or when just the
growing tips are harvested compared to the treatments that have outperformed the others in the
other two groupings (regrowth and marketable yield). This means that when applying cutting
treatments, total yield will not increase in most scenarios, but rather decrease compared to
leaving the plants to grow untouched. The only advantage to cutting treatments compared to a
control is the quality of the yield, as it is unlikely for a consumer to value a plant which was left
to grow fibrous and tough. These results are especially pertinent to the treatment where just the
growing tips were taken, as the treatment went from the lowest yielding to one of the highest
when you consider total biomass. This suggests that there are still improvements to be made for
this treatment, as the plant is still producing a lot of biomass in the stems rather than producing
more growing tips as in the weekly treatment. By cutting more frequently than every two weeks
the plant would likely produce more tips rather than the thick stems which lead to such high total
biomass.
This research showed that longer time periods between cuttings will produce more yield
but lower quality and less marketability. The stems and leaves harvested from the control were
far from market quality indicating that it is unlikely the plants could go for much longer than
three weeks between cuttings and continue to maintain quality. Cutting frequency also appears to
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be connected to the harvest method. If only the leaves or growing tips are being harvested, a
shorter cutting period of one to two weeks may increase yield and quality, while if the plants are
cut lower and the stems are harvested, the period can be extended to three weeks or possibly
more to maximize yield without sacrificing quality.
Conclusions
Personal communication with Ontario farmers led to the idea that the “customer”
treatment based on the typical method of cutting the larger stems low to the ground would
encourage adventitious shoot growth and outperform the other treatments. While this treatment
did stimulate new growth and resulted in the highest yields, cutting straight across the entire
plant at a set height of 15 cm above ground level every three weeks yielded an amount which
was not significantly different. This finding has promising real world implications for larger
operations as the same amount can be harvested with far less labour (and perhaps even
automated) while maintaining quality.
There are certain customers that prefer just the growing tips of edible amaranth but the
harvest treatment we explored, of only selecting these tips every two weeks stunted marketable
yields compared to the other treatments. A significantly better approach to harvesting what
appears to be the same portion of the plant was the weekly harvest treatment. By cutting more
frequently the plants appeared to create far more growing tips to be harvested instead of
investing in fewer. While the yield is still low compared to other treatments it is important if the
amaranth is being grown specifically for a consumer base that favours the tender growing tip.
The cutting treatments could be optimized by harvesting based around weather and other
factors rather than being held to a set interval. We chose a set interval so that we could
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standardize treatments and to fit scientific methodology. Regardless, the amount harvested in the
field trials is already more than promising and this research showed that edible amaranth has the
potential to be a viable crop for farmers in southern Ontario.
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References
Abbasi, A. M., Khan, M. A., Shah, M. H., Shah, M. M., Pervez, A., and Ahmad, M. 2013. Ethnobotanical appraisal and cultural values of medicinally important wild edible vegetables of Lesser Himalayas-Pakistan. Journal of Ethnobiology and Ethnomedicine, 9: 66.
Akubugwo, I. E., Obasi, N. A., Chinyere, G. C., and Ugbogu, A. E. 2007. Nutritional and chemical value of Amaranthus hybridus L. leaves from Afikpo, Nigeria. African Journal of Biotechnology, 6: 2833-2839.
Filson, G. C. and Adekunle, B. 2017. Greater Toronto area preferences for ethnocultural vegetables. Pages 33-54 in S. McMenemy, ed. Eat Local, Taste Global: How Ethnocultural Food Reaches Our Tables. Wilfrid Laurier University Press, Waterloo, Canada.
Harper, J.L. 1977. The influence of density on form and reproduction. Pages 195-228. Population Biology of Plants. London: Academic Press, London, UK.
Mager, H. J., Young, B. G., and Preece, J. E. 2006. Characterization of compensatory weed growth. Weed Science, 54: 274-281.
Materechera, S. A. and Medupe, M. L. 2006. Effects of cutting frequency and nitrogen from fertilizer and cattle manure on growth and yield of leaf amaranth (Amaranthus hybridus) in a South African semi-arid environment. Biological Agriculture & Horticulture, 23: 251-262.
Sauer J.D., 1967. The grain amaranths and their relatives: A revised taxonomic and geographic survey. Annals of the Missouri Botanic Garden, 54: 103-137.
Schwerzel, P.J. 1986. Amaranth: a nutritious crop for the developing world. Farming World, 12: 3-9.
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Table 1. Soil test results from samples taken in 2017 from Guelph Centre for Urban Organic Farming in Guelph, Farintosh Farms in Stouffville, and the Simcoe Research Station in Simcoe, Ontario, CanadaSoil Properties Guelph Stouffville SimcoepH 7.6 6.3 7.4Organic Matter (%) 5.2 2.7 2.0Phosphorus (ppm) 20 137 55Potassium (ppm) 87 111 135Magnesium (ppm) 304 71 175Calcium (ppm) 2832 1420 720Cation Exchange (MEQ/100 g) 18.1 9.2 5.5
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Table 2. Monthly precipitation and mean air temperature for 2017 at Guelph, Stouffville, and Simcoe, Ontario, Canada. Data were collected from the nearest Environment Canada meteorological station to each of the three sites.
Precipitation (mm) Mean air temperature (°C)Month Guelph Stouffville Simcoe Guelph Stouffville SimcoeJan 111 70 81 -3.6 -1.6 -1.9Feb 103 58 86 -1.8 -0.2 0.2Mar 61 68 111 -2.0 -0.5 -0.4Apr 117 111 107 8.1 9.4 9.7May 136 143 142 10.1 12.6 12.7Jun 176 98 84 17.4 19.4 19.6Jul 68 38 18 19.1 21.8 20.7Aug 48 75 33 17.3 20.1 18.9Sep 54 30 29 16.3 18.8 17.5Oct 90 58 105 11.0 13.3 12.6Nov 92 60 103 1.7 3.7 3.2Dec 55 40 60 -6.8 -5.2 -5.4
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Table 3. Mean (plus or minus standard error) regrowth weight of A.hybridus L. as affected by harvest approaches over six weeks at Farintosh Farms in Stouffville, Simcoe Research Station in Simcoe, and the Guelph Centre for Urban Organic Farming in Guelph, Ontario, Canada in 2017.Site Harvest approach Fresh weight
(kg m-2)Dry weight(kg m-2)
Ratio(fresh kg m-2/dry kg m-2)
Stouffville Weeklya 0.59±0.024d 0.18±0.042bc 3.74±0.694bBiweekly 0.78±0.052c 0.16±0.012b 4.97±0.399bTriweekly 1.26±0.053b 0.18±0.009b 6.89±0.383aCustomerb 1.89±0.117a 0.35±0.021a 5.46±0.453abTipsc 0.30±0.026e 0.07±0.008c 4.28±0.242b
Simcoe Weekly 0.96±0.044b 0.15±0.007b 6.35±0.277abBiweekly 1.24±0.083ab 0.18±0.008a 6.82±0.400abTriweekly 1.45±0.164ab 0.23±0.013a 6.34±0.391abCustomer 1.48±0.140a 0.22±0.022ab 6.78±0.181aTips 0.33±0.019c 0.06±0.003c 5.74±0.214b
Guelph Weekly 0.12±0.033a 0.05±0.006a 2.99±1.222bBiweekly 0.10±0.014a 0.02±0.001b 5.14±0.415abTriweekly 0.10±0.027a 0.02±0.003b 5.05±0.625abCustomer 0.34±0.126a 0.08±0.031ab 4.71±0.301abTips 0.08±0.014a 0.01±0.003b 6.12±0.699a
Note: Means followed by the same lowercased italic letter within a site and column are not significantly different according to a Tukey’s multiple range test (α=0.05).a Weekly, Biweekly and Triweekly treatments were cut at 15 cm above ground level. b Customer treatment mimicked Afro-Caribbean preference by cutting larger stems near the base every other week.c Tips treatment mimicked European preference by cutting just the below the growing tip every other week.
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Table 4. Mean (plus or minus standard error) marketable vegetable yield of A. hybridus L. as affected by harvest approaches over seven weeks at Farintosh Farms in Stouffville, Simcoe Research Station in Simcoe, and the Guelph Centre for Urban Organic Farming in Guelph, Ontario, Canada in 2017.Site Harvest approach Fresh weight
(kg m-2)Dry weight(kg m-2)
Ratio(fresh kg m-2/dry kg m-2)
Stouffville Weeklya 1.75±0.102b 0.30±0.042ab 6.07±0.876ab
Biweekly 1.85±0.114b 0.36±0.092abc 5.94±1.043ab
Triweekly 2.60±0.131a 0.33±0.010b 7.96±0.253a
Customerb 2.56±0.143a 0.42±0.030a 6.05±0.398b
Tipsc 0.50±0.019c 0.10±0.009c 5.36±0.308bSimcoe Weekly 3.46±0.242a 0.40±0.042a 8.74±0.811a
Biweekly 3.60±0.379a 0.45±0.058a 8.08±0.269aTriweekly 4.02±0.340a 0.50±0.030a 8.01±0.679aCustomer 3.77±0.265a 0.47±0.032a 8.08±0.107aTips 0.48±0.009b 0.08±0.002b 5.91±0.0417b
Guelph Weekly 0.36±0.117ab 0.08±0.009a 3.74±0.694bBiweekly 0.41±0.059a 0.07±0.015ab 4.97±0.399bTriweekly 0.50±0.216ab 0.09±0.044ab 6.89±0.383aCustomer 0.74±0.267ab 0.14±0.048ab 5.46±0.453abTips 0.15±0.010b 0.02±0.004b 4.28±0.242b
Note: Means followed by the same lowercased italic letter within a site and column are not significantly different according to a Tukey’s multiple range test (α=0.05).a Weekly, Biweekly and Triweekly treatments were cut at 15 cm above ground level. b Customer treatment mimicked Afro-Caribbean preference by cutting larger stems near the base every other week.c Tips treatment mimicked European preference by cutting just the below the growing tip every other week.
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Table 5. Mean (plus or minus standard error) total vegetative biomass yield of A. hybridus L as affected by harvest approaches at Farintosh Farms in Stouffville, Simcoe Research Station in Simcoe, and the Guelph Centre for Urban Organic Farming in Guelph, Ontario, Canada in 2017.Site Harvest approach Fresh weight
(kg m-2)Dry weight(kg m-2)
Ratio(fresh kg m-2/dry kg m-2)
Stouffville Weeklya 2.74±0.181c 0.59±0.0280d 4.65±0.348abBiweekly 2.91±0.104c 0.67±0.090bcd 4.50±0.491abTriweekly 3.94±0.201b 0.77±0.031c 5.10±0.107bCustomerb 3.64±0.454bc 0.77±0.103abcd 4.78±0.1.91bTipsc 4.61±0.224b 0.94±0.033ab 4.89±0.137bControld 5.60±0.147a 0.99±0.021a 5.64±0.084a
Simcoe Weekly 4.78±0.246a 0.58±0.042b 8.35±0.479aBiweekly 5.03±0.313a 0.62±0.066b 8.10±0.2079aTriweekly 5.48±0.507a 0.69±0.015b 7.91±0.469abCustomer 5.66±0.602a 0.74±0.040b 7.71±0.164aTips 5.48±0.433a 0.89±0.100ab 6.15±0.095cControl 5.58±0.361a 0.86±0.019a 6.50±0.297bc
Guelph Weekly 0.61±0.203a 0.14±0.043a 3.98±0.729abcBiweekly 0.64±0.068a 0.13±0.011a 4.83±0.313aTriweekly 0.92±0.384a 0.23±0.167a 4.14±0.244abCustomer 1.47±0.514a 0.42±0.274a 3.66±0.198bcTips 0.80±0.114a 0.24±0.085a 3.39±0.492abcControl 1.00±0.244a 0.39±0.265a 2.81±0.378c
Note: Means followed by the same lowercased italic letter within a site and column are not significantly different according to a Tukey’s multiple range test (α=0.05).a Weekly, Biweekly and Triweekly treatments were cut at 15 cm above ground level. b Customer treatment mimicked Afro-Caribbean preference by cutting larger stems near the base every other week.c Tips treatment mimicked European preference by cutting just the below the growing tip every other week.d Control treatment plants were not harvested until the final harvest date.
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