ORIGINAL ARTICLE

Evaluation of Heat Tolerance of Hybrid Wheat by Chlorophyll Fluorescence

Heat-stress during grain filling period in wheat has pronounced effect on yield in major wheat growing agro-ecological zones. The effect of heat-stress on chlorophyll fluorescence in hybrid wheat genotypes was studied. Twelve wheat genotypes including 9 hybrids [F₁(2), F₁(3), F₁(4), F₁(5), F₁(6), F₁(7), F₁(8), F₁(9), F₁(10)] and 3 commercial cultivars (Suntop, Sunmate and Spitfire) were grown in pots under controlled-environment greenhouse [22/15 ºC (day/night)]. Heat stress [35/22 ºC (day/night)] was applied in growth chamber for three days at anthesis. Suntop is the male parent of F1(6) hybrid. The main objective in the present study was to examine the genetic variation for heat tolerance among studied wheat hybrids and commercial cultivars by evaluating differences in their chlorophyll florescence and their derived parameters. Results showed that genetic variations in chlorophyll fluorescence’s parameters were very prominent among studied wheat genotypes under heat treatments. Most of the wheat genotypes showed decreased chlorophyll fluorescences (Fv/Fm and Fv’/Fm’) and non-photochemical quenching (qN) at heat stress compared to control and post-heat conditions. But in PSII efficiency (PhiS2) and electron transport rate (ETR) maximum wheat genotypes showed increased values of these parameters at heat stress condition compared to control and post-heat conditions. Hybrid varieties exhibited better performance in most of the chlorophyll fluorescence’s parameters compared to commercial cultivars. Hybrid variety F1(6) was found to be superior in maximum studied characteristics than its male parent Suntop.