Selection of Appropriate Physiological Parameters to Identify Heat Tolerant Wheat Varieties.

With the increased global temperature affecting wheat production in many ways, it is important to identify heat tolerant wheat varieties and speed the selection process at the same time. This paper identifies the plant physiological parameters that are important to detect heat stress tolerance in wheat. A total of 100 genotypes from double haploid population developed by Wheat Improvement Team at Oklahoma State University were studied using the Controlled Environmental Research Laboratory at OSU. A set of genotypes was maintained under controlled conditions (22/16 °C) throughout the experiment and another set was subjected to heat stress (32/26 °C) starting at 65 days after sowing. Photosynthetic rates (Pn), stomatal conductance (g_s), electron transport rate (ETR), internal carbon dioxide concentration (Ci), photochemical quenching (Qp) and fluorescence (F) were recorded twice at 3 days interval after initiating heat stress treatment, using LI-6400 XT (Licor Inc., NE, USA). Results of MANOVA test show that there is significant difference between populations on the basis of parameters studied. Linear discriminant analysis was conducted to identify the variables which reflected the differences between populations most accurately. Based on linear discriminant functions, results show that stomatal conductance is the most important plant physiological parameter to distinguish between heat stressed and non-stressed population in the vegetative stage. Further, an experiment is being conducted to relate these results with yield for validation. In conclusion, the use of stomatal conductance might provide an opportunity to speed up the selection process by using simple instruments and be beneficial for areas with limited technological reach.