Simulation of climate change impact on water productivity of maize in central Punjab

Abstract

Field experiments were conducted at the Research Farm, Department of Climate Change and Agricultural Meteorology, Punjab Agricultural University, Ludhiana during kharif 2016 and 2017. Maize variety PMH-1 was sown with a row spacing of 60 cm and plant spacing of 20 cm on three dates viz. D₁-Third week of May, D₂-Second week of June and D₃- First week of July under two irrigation levels i.e. irrigation at IW: CPE of 1.00 (I₁) and 0.75 (I₂) and mulch viz. application of straw mulch @ 5 t ha^–1 (M₁) and without mulch (M₂) in split plot design (SPD) with dates of sowing and mulch in main plots and irrigation levels in the sub-plots. Actual moisture depletion by the crop under different treatments was recorded by soil moisture depletion method. Among the dates of sowing, moisture extraction was observed to be highest under D₁ (540.5 and 477.5 mm), whereas among the irrigation and mulch levels, it was lower under IW/CPE = 0.75 (461.2 and 376.9 mm) and mulch application @ 5t/ha (473.0 and 387.1 mm) during both the seasons. The ET_o was calculated by open-pan evaporation, Priestley-Taylor, FAO-56, Papadakis and CROPWAT models. Among all the four methods, the Priestley-Taylor method gave higher ET_o in all three dates of sowing and it was close to open-pan evaporation values except in first date of sowing during 2016, in which ET_o was higher in FAO-56 (602.4 mm). The crop coefficients calculated by Papadakis method were comparatively higher (1.3 and 1.1 mm) as compared to that calculated by CROPWAT method (1.2 and 1.0 mm) and FAO-56 (1.0 and 1.1 mm) methods gave higher values of crop coefficients as compared to Priestley-Taylor method of DSSAT model (1.0 and 0.9 mm). The water use efficiency of maize was higher in D₂ (11.02 kg/ha-mm, 13.43 kg/ha-mm) w.r.t grain yield as compared to D₃ (10.72 kg/ha-mm, 12.97 kg/ha-mm) and D₁ (9.69 kg/ha-mm, 10.65 kg/ha-mm) w.r.t grain yield, during 2016 and 2017 respectively. Among mulch and irrigation treatment was higher in M₁ and I₂ levels in both the years. Simulation results showed that rise in temperature would result in decreased water productivity of maize, but this decrease could be compensated by increase in CO₂ concentration.