Response of Water Stress Parameters to Alternate Wetting and Drying (AWD) Method of Water Management in Low land Rice (Oryza sativa)

Response of Water Stress Parameters to Alternate Wetting and Drying (AWD) Method of Water Management in Low land Rice (Oryza sativa).

Alternate Wetting and Drying (AWD) is an irrigation technique where water is applied to the field a number of days after disappearance of ponded water. The treatments consisted of continuous submergence besides AWD irrigation regimes with two ponded water depths of 3 and 5 cm and drop in ponded water levels in field water tube below ground level to 5, 10 and 15 cm depth. The eight treatments were laid out in randomized block design with three replications. The irrigation water applied effective rainfall and seasonal volume of water input varied from 708 to 1390 mm, 216 to 300 mm and 1048 to 1646 mm, respectively on pooled basis. Irrigation water applied in AWD irrigation regimes amounted to 50.9 to 82.1% of continuous submergence (1390 mm).Water stress parameters viz., relative water content (90.00 to 91.81% in 2013 and 92.19 to 92.77% in 2014) and leaf water potential (10.0 to 11.8 –bars in 2013 and 10.3 to 12.6 –bars in 2014) reflecting plant water balance were higher in continuous submergence depth of 3 cm from transplanting to PI and 5 cm from PI to PM, comparable values of RWC and LWP were also registered when the crop was flooded to a water depth of 5 cm between 15 DAT to PM as and when ponded water level drops to 5 cm BGL in field water tube and 10 cm BGL in field water tube. Likewise in AWD irrigation regime flooding to a water depth of 3 cm from 15 DAT to PI and 5 cm from PI to PM as and when ponded water level drops to 15 cm BGL in field water tube markedly lower the relative water content and leaf water potential...