Screening of wheat (Ttiticum aestivum L.) cultivars for terminal heat stress tolerance by using biochemical pointer

Among abiotic factors, high temperature is severe constraint limiting crop production. Wheat is a major cereal and staple crop of Pakistan. An experiment was conducted (winter season 2018-19) to expose the effect of warmness induced biochemical alteration on morphological points of Pakistani wheat cultivars. Randomized complete block design (RCBD) with split plot arrangement having three replications was used to experiment. Heat stress treatments H0 = No heat imposition, H1 = heat imposition from (Feekes Scale = 10 to 10.5) booting to complete heading were randomized in main plots while varieties in subplots. Galaxy-2013, Gold-2016, Ghazi-2016, Aas-2011, Johar-2016, Pakistan-2013, F-8, Sahar-2006, Jauher-2016 and AARI-2011. Under heat stress, a smaller reduction in chlorophyll fillings and improvement in antioxidant activities were showed by Ghazi-2019, Aas-2011 and Jhor-2016. Among all other cultivars, higher chlorophyll deprivation and depletion in antioxidant activities under heat stress over control was observed. Reasonably lesser grain filling rate, higher duration, number of grains per spike and yield was detected for cultivars Ghazi-2019, Aas-2011, Jhor-2016 and F-8 under heat stress over control. Convincingly, based on biochemical response and morphological indicators genotypes Ghazi-2019, Aas-2011 and Jhor-2016 manifested heat tolerance. Genotype Fareed-2006 and F-8 manifested medium tolerance. Whereas, genotype AARI-2011, Galaxy-2013, Gold- 2016, Jhor-2016, Pakistain-2013, Sher-2006 and Ujala depicted susceptibility to terminal heat stress.