Assessing congenial soil temperature and its impact on root growth, grain yield of summer rice under varying water stress condition in Lower Gangetic Plain of India

Abstract

Abstract Increasing winter temperature in lower Gangetic Plain of India has put a threat to the cultivation of summer rice along with decreasing fresh water availability. Increasing ambient temperature also increase the soil temperature in the root zone of the crop. Thus, the effect of soil temperature over an optimum value may be detrimental for the root growth which turns into reduction of grain yield. Keeping in mind this situation, an experiment was carried out during 2014 and 2015 on summer rice in University Research Farm. Three transplanting dates and four irrigation regimes were chosen so that the crop experiences extreme weather as well as water stress condition. It is found that the mean soil temperature has a gradual increasing trend with advancement of crop growth. A significant and exponential increase in root weight was recorded with the increase in soil temperature. It is found that root growth was reduced when soil temperature increased beyond a critical value of 34 °C due to delayed transplanting and reduction of grain yield was noticed. So the summer-rice farmers are advised to complete transplanting within first fortnight of February to avoid yield reduction due to delay.