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Tomato (Solanum lycopersicum L.) is known as protective food because of
its special nutritive value and wide spread production. Planting time is one of the most
important factors among the various cultural practices followed for the production of
tomato that greatly influence its growth and yield. Weather parameters play an
important role in the growth and yield of tomato. The crop is sensitive to both low and
high temperatures. Moisture stress is one of the major problems for the cultivation of
tomato, which affects the production adversely. Hence much attention has to be paid
on the use of soil cover.
The present investigation “Crop weather simulation model in tomato
( Solanum lycopersicum L.) ” was carried out in the Department of Agricultural
Meteorology, College of Horticulture, Vellanikkara during 2017-18, to calibrate the
genetic coefficients for tomato using DSSAT CROPGRO-Tomato model and to
evaluate the micrometeorological aspects of tomato under different growing
environments. The field experiment was conducted at the STCR plot, College of
Horticulture, Vellanikkara during September (2017) to March (2018). Split plot design
was adopted with six dates of planting viz., 15th September,
1st October , 15th
October, 1st November, 15th November and 1st December as the main plot treatments
and three types of mulches viz., black top white bottom, white top black bottom
polythene, straw mulch and control as the sub plot treatments. The number of
replications for the experiment was three.
The daily weather parameters like maximum and minimum temperatures,
forenoon and afternoon relative humidity, bright sunshine hours, pan evaporation,
wind speed, rainfall and number of rainy days were recorded during the entire crop
growing period, to determine the crop weather relationship.
The daily soil temperature determined during the crop growing period showed
increasing trend towards the late plantings, whereas weekly soil moisture showed
decreasing trend towards late plantings. Black top white bottom polythene retained
highest soil temperature and soil moisture.
Soil pH, organic carbon and microbial biomass carbon were found to be lowest
in control when compared to mulched plots. The analysis of available nitrogen,
phosphorus and potassium showed that, the soil samples taken after the harvest of the
crop recorded high soil nutrients compared to initial samples. The available soil
nutrients (N, P and K) was does not vary between the dates of planting, whereas
mulched recorded more soil nutrients compared to control. The increased availability
of available nitrogen and phosphorus in polythene mulched plot due to the optimum
soil temperature, optimum soil moisture levels, increased mineralization, reduction in
nutrients leaching and lower uptake of nutrients by weeds. The increased availability
of available potassium in paddy straw mulched plot might be due to addition of
potassium to the soil which is present in the straw.
In the present investigation, it is clear that the uptake of plant nutrients
(N, P, K) was increased due to the addition of mulches, due to sufficient soil moisture,
optimum soil temperature, reduction in nutrients leaching, nutrient utilization and
reduction in the weeds competition.
The maximum height of the plants was found to be highest during
15th September and lowest during 1st December planting. Plant height was high in the
mulched plots when compared to the control.
The number of trusses per plant for first three plantings were found to be high,
whereas it was low in last two plantings. The number of fruits per plant was high in
first four plantings and was lowest in last planting. The plants under black top white
bottom polythene recorded highest and control recorded lowest number of fruits per
plant. The mean yield of 15th September planting was highest and lowest was recorded
in control. Yield was high in plants with black top white bottom polythene and straw
mulch and were on par. Low number of weeds were recorded in mulched plots,
compared to control. The analysis of correlation between weather and yield parameters
showed that with increase in the minimum temperature, relative humidity, rainfall and
rainy days, yield increased whereas, with increase in the maximum temperature, wind
speed, bright sunshine hours and evaporation the yield decreased.
Number of days taken for different phenophases viz., first flowering, fifty
percent flowering, first fruiting, fifty percent fruiting, harvesting and total duration
decreased towards last planting. The duration of the plants with mulches showed long
duration compared to control. The correlation between weather and phenophases was
significant.
The fruit yield and duration of phenophases were influenced by accumulated
growing degree days, heliothermal units and photothermal units. The highest recorded
accumulated growing degree days, heliothermal units and photothermal units was
during 1st December planting. Hence lower fruit yield and less duration for attaining
maturity was observed in last dates of planting.
The crop genetic coefficients that influence the occurrence of
developmental stages in the CROGRO – Tomato model were calibrated, to achieve
the best possible agreement between the simulated and observed values. Predicted
yield, phenology and leaf area under different planting dates were reasonably close to
the observed values.
Thus, the study revealed that there is an influence of mulches on the growth
and
yield
of
tomato
especially in
dry conditions.
By modifying the
micrometeorological conditions, the yield of the tomato can be enhanced during off
season. Crop simulation models are efficient in simulating the growth and yield of
tomato.