Yield response of wheat grown under periodic heat stress imposed by using mini heat tents

Abstract

AbstractHeat stress is a major factor affecting growth and productivity of wheat. A study was conducted at Ludhiana, Punjab, India with an objective to find out the impact of periodic (15 days) heat stress in wheat grown under natural field conditions. The heat stress treatments consisted of control (no heat stress), heat stress during 0–15, 16–30, 31–45, 46–60, 61–75, 76–90, 91–105, 106–120, 121–135, 136 days after sowing (DAS) to harvest. Heat stress (seasonal average maximum temperature higher than optimum temperature by 4.3 and 2.7°C during 2016–2017 and 2017–2018, respectively) was imposed by using mini heat tents made of galvanized iron pipes covered with transparent polyethene sheets. The mini heat tents were installed for 15 days duration in the plots according to the treatments and were removed at the end of 15th day. On the next day, they were installed in plots of the next treatment level. Heat tents were never installed on control plots. Increase in temperature in the mini heat tents was not controlled and was allowed to increase naturally. However, the excessive heating in the tents was prevented by opening the southern side during day time. Heat stress resulted in a significant increase in the membrane injury index and a decrease in chlorophyll content. Heat stress reduced the activity of dehydrogenase in rhizosphere and bulk soil. Heat stress from 76–90 and 91–105 DAS significantly reduced the ear length and number of grains ear‐1. Heat stress during 106–120 and 121–135 DAS decreased thousand grain weight significantly. Application of heat stress between 61–75, 76–90, 91–105, 106–120 and 121–135 DAS decreased grain yield significantly by 16.0, 19.8, 22.1, 16.4 and 14.8% during 2016–2017 and 11.8, 15.3, 18.8, 13.9 and 12.6% during 2017–2018, respectively, as compared to that obtained under control conditions. Apart from effects of heat stress on crops, the present study also highlights the design and possibility of using cost‐effective, small size and portable mini heat tents for conducting heat stress studies in different field crops.