Identifying Physiological Traits Associated with High Temperature Tolerance in Sunflower (Helianthus annuus L.) Genotypes

The objective of the study is to identify the physiological traits associated with seed yield in sunflower. An experiment was conducted at ICAR-Indian Institute of Oilseeds Research, Narkhoda Farm, Rajendranagar, Telangana during rabi (Jan-May) 2019 and 2020 to find out the response of Sunflower genotypes to high temperature (HT) stress. Here, 47 genotypes were screened in the first year and 14 genotypes were identified which are evaluated in the second year under timely (control, S1) and delayed (HT stress, S2) sowings. These traits in the two years are correlated with seed yields (SY) which were differed under S1 and S2. The per se performance indicated that the expression of most traits was reduced under S2 except canopy temperature in 2019. The genotype AKSF 6-3B with the highest SY were characterized by chlorophyll content, maximum quantum efficiency, relative water content, pollen viability, leaf area index, photosynthetic rate and transpiration at vegetative stage under high temperature. The diverse genotypes identified with promising traits can be used in breeding programs to develop new varieties.