INTEGRATION OF PHYSIO-BIOCHEMICAL PROCESSES AT DIFFERENT PHENOLOGICAL STAGES OF WHEAT (TRITICUM AESTIVUM L.) PLANTS IN RESPONSE TO HEAT STRESS

摘要

A study was conducted to assess the influence of heat stress imposed at different growth stages of wheat (Triticumaestivum L.) plants. Four wheat cultivars namely S-24, Saher-2006, Lasani and AARI-10 were subjected to high temperature(HT) stress at tillering and booting phenological phases. Under stress conditions, root and shoot fresh weights, membranethermostability (MTS) and non-photochemical quenching (NPQ) were significantly perturbed in all four wheat cultivars atboth developmental stages. However, HT stress did not influence all the other attributes significantly including shoot freshweight, chlorophyll a and b pigments, photosynthetic rate (A), leaf water (Ψw), internal CO2 (Ci), osmotic (Ψs) and turgor(Ψp) potentials, transpiration rate (E), water-use-efficiency (A/E), stomatal conductance (gs) as well as Fv/Fm ratio. Amongall wheat cultivars, cv. Lasani performed better in shoot and root fresh weight, and chlorophyll a contents at the tilleringstage, while in MTS at the booting phase, cv. S-24 in shoot fresh weight, E, and gs at the boot stage and highest MTS andWUE at the tillering stage. However, cv. AARI-10 performed well in root fresh weight, Ψw, Ψs, Ψp,,WUE and NPQ whenstress was applied at the boot stage, while E and Fv/Fm in this cultivar on exposure to stress at the tillering stage. CultivarSaher-2006 performed better in gs, leaf Ψs and Ψp at the tillering stage, while Fv/Fm was recorded better at the boot stage andA in the same cultivar at all growth stages. Overall, HT stress applied at different growth stages was only effective inaltering root fresh weight, MTS and NPQ in all four wheat cultivars. Of all wheat cultivars, cv. AARI-10 performed better ingrowth and physiological attributes examined in the present study under HT stress applied at different phenological stages.