Unraveling genetic parameters of physio morphological traits of terminal heat stress tolerance in bread wheat Triticum aestivum L

Abstract

The present investigation entitled Unraveling genetic parameters of physio-morphological traits of terminal-heat stress tolerance in bread wheat (Triticum aestivum L.) was conducted at three different locations; namely Crop research farm, Nawabganj, Crop research farm, Araul and Crop research farm, Daleep Nagar during crop season of Rabi 2021-2022 and 2022-2023 under normal (non-stressed) and late sown (heat-stressed) conditions. with the objectives (i) To study the adaptive physio-morphological traits in bread wheat genotypes tolerant to terminal-heat stress (ii) Physiological analysis of terminal-heat stress tolerant and susceptible lines using physiological marker (iii) To examine genetic diversity among wheat varieties/lines with the help of principal component analysis (iv) To work out direct and indirect effects of different characters on yield (v) To find out stable genotypes under terminal heat stress and normal condition. The field experiments were planted comprising 80 germplasm of bread wheat. Therefore, our experimental trials were conducted in 12 environments (E1 to E12), for the identification of superior yielding and stable germplasm accessions possessing heat-stress tolerance. The field experiments were laid out in Augmented Block Design (ABD). Each experimental plot consisted of three rows of 2m length with 20 cm spacing between rows covering an area of 2 m x 0.20m (1.2 m2) under irrigated condition. Observations were recorded on twenty- six quantitative characters viz., Days to 50% heading, Grain filling period(days), Flag leaf length(cm), Flag leaf width(cm), Flag leaf area(cm2), Plant height (cm), Peduncle length(cm),Spike bearing tillers per plant, Chlorophyll content, Canopy newlinetemperature depression(0C), Plant waxiness (0-10 scale), Leaf rolling (0-10 scale), Spike length(cm), Number of spikelets per spike, Physiological maturity(days), Plant biomass (g), Grain weight per spike, Number of grain per spike, Number of grain per plant, Grain length(mm), Grain width(mm)