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MODELLING CROP WATER PRODUCTIVITY OF RICE UNDER DIFFERENT CULTIVATION METHODS

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2018
A sarangi
DIVISION OF AGRICULTURAL ENGINEERING INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI -
MODELLING CROP WATER PRODUCTIVITY OF RICE UNDER DIFFERENT CULTIVATION METHODS
Ph.D

Improving crop water productivity through adoption of water savings technologies is essential to achieve the goal of per drop more crop. Rice being the highest water consuming crop in agricultural sector necessitates effective water saving approaches for enhancing water productivity. Judicious water management can be ensured by carrying out water budgeting investigations, which provides a detailed account of utilization and wastage of applied irrigation water. Moreover, crop growth simulation model after its successful validation assist in selection of appropriate irrigation scheduling and cultivars for enhancing grain yield and water productivity under varying irrigation regimes and changing climate conditions. Keeping this in view, an effort was made to evaluate the water productivity of rice cultivars under different cultivation methods and irrigation regimes. A field experiment under three prevailing rice cultivation methods in Trans-Gangetic plains of India viz. Conventional Puddled Rice (CPR), System of Rice Intensification (SRI) and Direct Seeded Rice (DSR) was conducted at research farm of ICAR-IARI, New Delhi and acquired data was subsequently used for simulating grain yield using crop models. Besides this, different input and output parameters of water budgeting in three rice cultivation method were estimated. The deep percolation beyond root zone (Dp) was found to be a major loss in rice cultivation followed by Evapotranspiration (ET). Dp losses were 54.9%, 52.7% and 23.1% of total applied water for CPR, SRI and DSR methods, respectively in year 2013 and, 57.4%, 56% and 36.1% of total applied water for CPR, SRI and DSR methods, respectively during 2014. The highest grain yield was observed in PRH-10 rice cultivar under SRI method with adequate irrigation having grain yield of 5.93 t ha-1 and 5.72 t ha-1 during 2012 and 2013, respectively. Whereas, during 2014, the highest grain yield of 6.30 t ha-1was observed in Pusa Sugandh 5 cultivar under SRI method with adequate irrigation. Therefore, SRI method with adequate irrigation was found to produce highest grain yield. Further, the highest water productivity was observed under PRH-10 cultivar in DSR method with 25% deficit irrigation in 2012 (5.35 kg/ha-mm), under PRH-10 cultivar in SRI method with deficit irrigation in 2013 (3.57 kg/ha-mm) and Pusa Sugandh 5 cultivar in SRI method under deficit irrigation in year 2014(6.06 kg/ha- 88 mm). AquaCrop model validation performance for grain yield was with overall R2 0.78, E 0.98, d index 0.89, RMSE 0.60 and nRMSE 0.14. Moreover, CERES-Rice model predicted grain yield with R2 0.94, E 0.69, d index 0.92, RMSE 0.50 and nRMSE 0.12. Besides future grain yield and water productivity was predicted up to 2025 using the calibrated and validated AquaCrop model, future climate data generated using CLIMGEN and the CROPWAT. It can be suggested that the SRI method with adequate irrigation will produce highest yield. The model prediction showed that the highest yield in next 10 years will be for PRH 10 cultivar (6.03 t ha1) from 613 mm of irrigation water. Whereas, highest water productivity (6.39 kg/ha.mm for SRI deficit and 5.87 for DSR deficit in year 2022) will be achieved under deficit irrigation for the short term prediction up to 2025. Although the SRI method with deficit irrigation showed highest water productivity, DSR method with deficit irrigation has also given very good results. Keywords: AquaCrop, DSSAT, climate change, rice cultivation, deficit irrigation

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