Impact of Soil Moisture Stress on Rice Productivity in Warming Climate over Indian Mid-Indo-Gangetic Plain

Crop failure and yield reduction due to lack of sufficient irrigation are very common, which can be minimised by providing irrigation during the most sensitive crop growth stages. This study aims at determining the most effective crop growth stage based on soil moisture stress, which adversely affects yield of the rice crop the most. Zadoks scale was used to divide crop period into representative growth stages on weekly basis. The weekly moisture content of soil was estimated using water balance equation. The crop is under stress when the soil moisture content was found less than the temporary wilting point of soil. Critical growth stages were determined by comparing the yield during different stress fetched growth stages with maximum and potential yield. Maximum yield reduction reported in the year 2009 (80.74%) followed by 2004 (74.46%) is due to soil moisture stress during the critical growth stages of rice which is reflected by a low amount of rainfall during these years. Among various growth stages panicle emergence from boot (9th week after sowing), beginning of anthesis (10th week after sowing) and completion of anthesis (11th week after sowing) were the most susceptible growth stages to water stress as percentage yield reduction was more as compared to other stages. Overall, it was concluded that if there is availability of only one irrigation, the yield reduction can be minimised by irrigating the crop during panicle emergence from boot stage (the 9th week after sowing).