Assessment of Low Intensity Solar Radiation Susceptibility in 20 Wheat Varieties under Field Conditions Grown in Indo-Gangetic Plains of India

Wheat productivity declines under agro-ecosystems and areas exposed to aerosols due to decline in quality and quantity of solar radiation. Identification of low light-tolerant wheat varieties (Triticum sps.) will help in enhancing the sustainability and productivity of the agroforestry systems as well as areas exposed to aerosol pollution. The field study was conducted to assess the effects of low intensity solar radiation (LR) on 20 wheat varieties in terms of growth, stay green, gaseous exchange, yield attributes, and tolerance indices. Results indicate the increase in plant height and leaf area, reduction in photosynthesis (Pn), stomatal conductance (gs), and transpiration (Tr) in all the varieties grown under LR compared to normal radiation. The varieties, K68 and HD2643, exhibited maximum stay green compared to other varieties. LR caused reduction in biological (35%) and economic (46%) yield of wheat. Among the indices, mean productivity (MP), geometric mean (GM), stress tolerance index (STI), and yield index (YI) were positively correlated (P ≤ 0.05) with grain yield under LR (Ys) and NR (Yp). Cluster analysis indicated that varieties–HD2643, K68, Kalyansona, and C306 varieties were most LR tolerant, while DL1266-1, DL1266-2, and Moti were moderately tolerant and rest of the varieties exhibited LR susceptibility.