Water and energy productivity of rice as influenced by duration of cultivars, dates of transplanting and irrigation regime in north-western India

A field experiment was conducted to compare water productivity of short- and long-duration rice cultivars transplanted on different dates under variable irrigation regimes during 2012-2014. The experiment was laid out in split plot design keeping combinations of three dates of transplanting (15 June, 25 June and 5 July) and two cultivars (PR 115 and PR 118) in main plots and four irrigation regimes [irrigation at 1, 2 and 3days after infiltration of ponded water (DIPW) and continuous ponding (CP)] in subplots. Crop transplanted on June 15 and 25 produced statistically similar but significantly higher grain yield than July 5 transplanted crop. Grain yield increased to the tube of 17.2 and 15.6% under early transplanting on June 15 and 25 compared to July 5, respectively. However, amount of irrigation water applied decreased by 23.6 and 12.9cm for July 5 and June 25 transplanted crop compared to June 15 transplanted crop, respectively. Apparent crop water productivity (ACWP) and total crop water productivity (TCWP) were significantly higher in June 25 transplanted crop than in June 15 and July 5. Similarly, energy use efficiency and energy productivity were also the highest in June 25 transplanted crops followed by June 15 and the least in July 5. Significantly higher grain yield was observed in cultivar PR 118 as compared to PR 115 under June transplanting dates (15 and 25 June). However, reverse trend was observed in late transplanting on July 5. Significant reduction in grain yield of PR 118 was recorded with delay in transplanting from June 25 to July 5, but PR 115 performed statistically similarly under all the three dates of transplanting. Irrigation water applied was 9.4% higher in PR 118 as compared to PR 115. ACWP and TCWP were 7.9 and 9.2% higher in PR 115 than in PR 118, respectively. ACWP and TCWP of PR 115 increased with delay in transplanting from June 15 to July 5, but differences between June 25 and July 5 remained nonsignificant. However, in the case of PR 118, ACWP and TCWP remained statistically similar between June 15 and June 25 and thereafter decreased significantly with delay in transplanting to July 5. Rice grain yield did not show any significant effect on irrigation application frequency, i.e. irrigate continuously or applied water at 1, 2 and 3 DIPW. However, 5.9, 15.2 and 23.5% higher irrigation water applied was recorded in continuous ponding than in irrigation application at 1, 2, and 3 DIPW, respectively. Apparent water productivity and energy use efficiency were 5.9 and 7.0, 15.3 and 13.0, and 19.8 and 23.0% higher in irrigation scheduling at 1, 2 and 3 DIPW than in CP, respectively.