Morpho-Physiological Characterization of Winter Wheat “Buster” Population during the Vegetative Stage under Heat Stress

Phenotypic assessment of breeding population is important to identify robust lines for incorporating into future breeding programs. The objective of this study was to identify potential lines from a wheat (Triticum aestivum L.) population, based on their morpho-physiological traits, for improved heat tolerance. A subset of 100 lines of the double haploid (DH) population named “Buster”, developed from two successful Oklahoma wheat varieties (Billings and Duster), was used in the study. Two experiments were conducted one in a greenhouse and the other in growth chambers. Data on plant height, tiller number, leaf number, and photosynthetic pigments were collected from the greenhouse;whereas the data on physiological parameters (leaf net photosynthesis (Pn), transpiration (T), stomatal conductance (gs), intercellular carbon dioxide concentration (Ci), electron transport rate (ETR), Photosystem II efficiency (Fv'/Fm') and instantaneous water use efficiency (IWUE)) were collected from the growth chambers. Buster lines were significantly (P < 0.05) different both morphologically and physiologically. A wide range of observations among genotypes for different morphological and physiological characteristics was found. For example, the Chlorophyll A:B ratio ranged from 1.8 to 4.3, average plant height ranged from 8.4 to 13.3 cm, and the net photosynthesis under heat stress ranged from 11.29 to 25.28 μmol CO2 m-2·s-1. The differences in leaf physiological parameters were more discernible under heat stress. This study provides a piece of baseline information on morpho-physiological characteristics of Buster lines, and identified lines can be used in future breeding programs for incorporating heat stress tolerance.