Simulating the impact of climate and irrigation schedule on performance of drip irrigated wheat (Triticum aestivum L.)
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Date
2017
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Punjab Agricultural University, Ludhiana
Abstract
The present study “Simulating the impact of climate and irrigation schedule on performance of drip irrigated wheat (Triticum aestivum L.)” was carried out at Punjab Agricultural University, Ludhiana, during 2014-15 and 2015-16. Experiment I was conducted in split plot design, keeping four sowing dates {25th October (D1), 10th November (D2), 25th November (D3) and 10th December (D4)} in main plots and five irrigation schedules {irrigation at 15 (FC15), 25 (FC25), 35 (FC35) and 45 (FC45) % depletion of soil moisture from field capacity (FC) and conventional practice (CP)} in sub plots. The results revealed that grain yield decreased by 8.3 and 8.7 % from D1 to D2, 10.7 and 10.6 % from D2 to D3 and 13.1 and 13.4 % from D3 to D4 during 2014-15 and 2015-16, respectively. The pooled grain yield and crop evapotranspiration (ETc) decreased by 29 and 17 % with delay in sowing from D1 to D4. The highest grain yield was obtained in FC15, which was significantly better than all other irrigation schedules. The pooled grain yield decreased by 30 %, ETc by 21 % and water productivity (WP) by 29 % in FC45 as compared to FC15. The grain yield and ETc in FC25 and CP were at par, but apparent water productivity was significantly higher in FC25 as compared to CP. The water saving in drip irrigation during 2014-15 was 62, 70, 77 and 83 % in FC15, FC25, FC35 and FC45, respectively, as compared to CP. The respective water saving during 2015-16 was 38, 44, 54 and 60 %. The DSSAT-CERES-Wheat model performed well [as revealed by high correlation coefficient (r), low root mean square error (RMSE) and low mean absolute percentage error (MAPE)] in simulating the days to anthesis (r=0.94 and 0.93; RMSE=3.40 and 4.10 days; MAPE=2.6 and 3.4 %), maturity (r=0.98 and 0.98; RMSE=3.70 and 3.30 days; MAPE=2.1 and 1.8 %), leaf area index (r=0.82 and 0.90; RMSE=0.47 and 0.43; MAPE=11.7 and 10.2 %), grain yield (r=0.87 and 0.96; RMSE=489.7 and 351.5 kg ha-1; MAPE=10.0 and 6.9 %), biological yield (r=0.91 and 0.96, RMSE=726.3 and 650.7 kg ha-1; MAPE=5.6 and 5.2 %) and ETc (r=0.72 and 0.96; RMSE=17.3 and 15.8 mm; MAPE=5.3 and 5.2 %) during 2014-15 and 2015-16, respectively. Experiment II was also conducted in split plot design, keeping three irrigation timings [three irrigations at crown root initiation, booting and milking (CBM); four irrigations at crown root initiation, tillering, booting and milking (CTBM) and five irrigations at crown root initiation, tillering, booting, milking and dough (CTBMD)] in main plots and four irrigation depth [5 cm at each stage in 2 splits (2SP); 7.5 cm at each stage in 3 splits (3SP); 10 cm at each stage in 4 splits (4SP); 7.5 cm at each stage conventionally (CP)] in sub plots. The results revealed that ETc and grain yield reduced by 14.5 and 13.4 % in CBM than CTBMD and 6.2 % reduction in grain yield of CTBM over CTBMD. The reduction in ETc from 4SP to 2SP was 7-23 % (15 % for pooled data) with the highest (347-406 and 328-396 mm) in 4SP and lowest (319-374 and 258-298 mm) in 2SP during 2014-15 and 2015-16, respectively. Similarly, grain yield decreased by 10.4 % when irrigation was applied at CP instead of 4SP. Though grain yield in 2SP and CP was similar, but 2SP resulted in 33 % water saving as compared to CP. The DSSAT-CERES-Wheat model performed well in simulating the days to anthesis (RMSE=2.06 and 4.96 days; MAPE=1.5 and 4.4 %), maturity (RMSE=3.83 and 4.52 days; MAPE=2.03 and 2.43 %), leaf area index (r=0.89 and 0.92; RMSE=0.37 and 0.47; MAPE=8.10 and 9.50 %), grain yield (r=0.92 and 0.97; RMSE=154.60 and 160.90 kg ha-1; MAPE=2.80 and 2.80 %), biological yield (r=0.67 and 0.58, RMSE=584.9 and 691.0 kg ha-1; MAPE=4.40 and 5.10 %) and ETc (r=0.95 and 0.96; RMSE=9.20 and 16.20 mm; MAPE=2.30 and 4.20 %) during 2014-15 and 2015-16, respectively. The study finally concluded that delay in sowing reduces the grain yield, while as frequent irrigation application that prevents any drought stress boosts the grain yield.
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