Optimising fertilizer applications to wheat cultivars under different sowing dates using CERES-Wheat model
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Date
2022-08
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G.B. Pant University of Agriculture and Technology, Pantnagar, District Udham Singh Nagar, Uttarakhand. PIN - 263145
Abstract
Wheat, (Triticum aestivum L.) is the most significant among the crops grown for the grain purpose worldwide. A field experiment was conducted during rabi season of 2021-22 at Crop Research Centre of G.B. Pant University of Agriculture and Technology, Pantnagar (Uttarakhand) for evaluation of two different wheat cultivars under three dates of sowing and varying levels of nitrogen fertilizer using CERES-Wheat model. The experiment was laid out in split-split plot design with 3 dates of sowing (D1= 9th November 2021, D2= 24th November 2021 and D3= 11th December 2021) as main plots, 2 wheat varieties (V1= UP-2855 and V2= DBW-187) and 3 levels of nitrogen fertilizer (N1=75 kg ha-1 with 60% K2O and 40% P2O5, N2=112.5 kg ha-1 with 60% K2O and 40% P2O5 and N3=150 kg ha-1 with 60% K2O and 40% P2O5) as sub plots. The experimental dataset of the field was used to calibrate and validate the CERES-Wheat (DSSAT v4.7) model for two cultivars of wheat. The findings showed that there was a fair amount of agreement between simulated and measured crop phenology, yield and its attributes using the genetic coefficients derived from calibration of the CERES-Wheat model under various treatment combinations as RMSE value lied within the confidence band limit (<20%). Different dates of sowing significantly influenced the crop growth attributing characters as well as yield and yield attributing characters. Due to the longer growing period, the crop sown on 9th November produced the highest crop growth characters, grain yield (4340.72 kg ha-1) and B:C ratio (2.15) while the crop sown on 11th December reported the lowest crop growth characters, grain yield (3036.44 kg ha-1) and B:C ratio (1.2). Among the varieties, DBW187 had higher crop growing characters, grain yield (3787.14 kg ha-1) and high B:C ratio (1.75) than UP-2855. It was mainly due to higher uptake of N, P and K by the variety DBW-187. Highest crop growing characters, grain yield (3967 kg ha-1) and B:C ratio (1.83) was noticed from the crop with 150 kg N ha-1with 60% K2O and 40% P2O5. The model's sensitivity was investigated for various irrigation
amount and it was discovered that the model was sensitive to variations in irrigation amount whether increased or decreased from normal irrigation. The simulation for grain yield was better with reasonable error (Grain yield RMSE= 8.32%) according to the model's overall performance as measured by the test criterion to evaluate the CERESWheat model for phenology and yield attributes of three dates of sowing, two varieties and three levels of nitrogen fertilizer. The model performed well in terms of simulating the decrease in grain yield that was observed in the experiment with delayed sowing and decreasing nitrogen fertilizer levels. The model's highest simulated grain yield for the DBW-187 variety of wheat under 9th November sowing date and with 150 kg N ha-1 with 60% K2O and 40% P2O5 was comparable to the observed grain yield of the experiment. Thus, it can be inferred that the model can be used to precisely predict the wheat yield at various regional level.