HEAT UNIT REQUIREMENT AND VALIDATION OF INFOCROP MODEL FOR Bt- COTTON IN MIDDLE GUJARAT AGROCLIMATIC REGION
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Date
2014
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Publisher
AAU, Anand
Abstract
Cotton [Gossypium hirsutum.) is one of the important fibre crop grown in tropical and sub-tropical regions of World. It being long duration its response to yield varies with variety and sowing time. It is raised in fchanf supplemental irrigation facilities are available. Bt-cotton is now being grown in most parts of Gujarat. Since the effect of weather on crop yield is complex, it needs deeper and clear understanding of climatic factors affecting the growth and yield of cotton. A field experiment was conducted during the kharif season of the year 2012 at Agronomy farm of B. A. College of Agriculture. In a split plot design with two Bt-cotton cultivars viz., Vikram-5 (Vi) and RCH-2 (V2) as a main plot treatment and three dates of sowing 25th May (Di), 10th J u n e (D2)and 25th June (D3) as sub-plot treatment with four replications. Three dates of sowing provided three different environment in terms of thermal and moisture regimes. The results indicated that the total crop duration varied with the dates of sowing. The crop life period was found to be shortened with delay in sowing, more pronounced being in cultivar Vikram-5. The seed cotton yield as well as total biomass yield of cotton as influenced by different treatments showed that the first date of sowing (Di) had produced significantly higher seed cotton yield as well as total biomass. A similar trend was also found in the yield attributing characters viz.,, plant height and number of boll per plant. Yield and yield attributes characters were found to decrease with delayed sowing. There was no significant difference between the varieties, though RCH-2 yield higher than Vikram-5. The results obtained during the course of study revealed that the different agrometeorological indices had played a significant role in deciding the growth and yield of cotton. The agrometeorological indices were found to affect the crop growth, development and yield differently in different phenophases during its growing period. Accumulated growing degree days (GDD) utilized by two cultivars of cotton to attain the maturity differed with three dates of sowing. The helio thermal unit (HTU) and photo thermal unit (PTU) were found to have similar effect as that of GDD. The heat use efficiency of Btcotton was also found maximum under 25th May sown crop and it decreased with delay in sowing. Correlation studies revealed that agrometeorological indices had highly significant positive association indices. The InfoCrop model was tested and validated for two cultivars of Bt-cotton {Gossypium hirsutum). Using the observed data sets of the cotton crop, the model was calibrated for genetic coefficients of two cultivars viz., Vikram-5 and RCH-2. Model showed its capability to predict phenology, maximum LAI, biomass and seed cotton yield of Btcotton. The simulated values were found to be very close to the observed data. The model performance was adjudged using various statistical parameters viz., mean absolute error (MAE), mean bias error (MBE), root mean square error (RMSE) and percent error (PE). The results showed that these values were within the acceptable limit. The seed cotton yield, biomass yield and maximum LAI were predicted accurately by the model with percent error of less than ±5 %. The results indicated that under biotic stress-free simulations, the InfoCrop model can be used to predict cotton 5deld under different environments for two cultivars of Bt-cotton.
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AGRICULTURAL METEOROLOGY, A Study