Role of High Nighttime Temperatures and Ethylene Production On Oxidative Damage, Lipid and Sugar Profiles in Soybean Pollen.

Soybean (Glycine max L. Merr.) is an important oilseed crop and it is well suited to temperate climate and because of high green house gas emission the global circulation model projected an increase of global temperature by 1.4 to 5.8°C. Much of this increase in average global temperature is by increase in nighttime temperature as a result of less radiant heat loss. Hence it necessitates studying the response of soybean to high nighttime temperature during flowering stage because soybean flower production and abortion is sensitive to change in temperature. The present study was formulated with a hypothesis that high nighttime temperature induces ethylene production, which causes flower abortion by altering pollen viability and application of the ethylene receptor inhibitor 1-Methylcyclopropene (1-MCP) can minimize stress ethylene response under high nighttime temperature stress conditions. To prove the hypothesis the following objectives were framed (i) to study the effect of high nighttime temperature and/or 1-MCP during flowering stage on pollen viability and germination, (ii) to assess the impact of high nighttime temperature and/or 1-MCP on pollen lipids and sugars content. The experiment was conducted in a split plot design with five replications. The main-plot treatments were temperature regimes and the subplot treatments were with and without 1-MCP. Data on leaf chlorophyll content, photosynthetic rate, stomatal conductance, PS II photochemical efficiency, quantum yield and electron transport rate were recorded in the leaf at four days interval. Similarly, pollen viability, germination, lipid and sugar profile were determined. The relations between changes in pollen viability and with ROS, lipids, sugars were assessed to explore the possibility of easy screening of soybean germplasum to high nighttime temperature stress.