Discerning phenological and morphological traits influenced by different agrometeorological indices in Sorghum bicolor L. under salt stress

Sorghum is an important feed and fodder crop in arid regions of the world and serve as a potential crop for understanding salt tolerance mechanisms in crops. Salinity affects crop production and reduce yield and biomass. In the present study, response of six sorghum varieties, including HC 260, HC 171, HC 136, HC 308, HJ 541, and HJ 513 were examined against variying levels of NaCl salt stress (0, 50 and 80 mM) under controlled conditions. Salinity adversely affected the sorghum growth and phenology, leading to delayed phenological stages of the crop. It also the growth rate, chlorophyll ratio, and biomass yield of the crop. Higher salt concentrations resulted in increased the accumulation of agrometeorological indices viz. accumulated growing degree days (AGDD), heliothermal units (HTU), heat use efficiency (HUE), photo temperature (Tphoto), nycto temperature (Tnycto), and inter-diurnal temperature range (TIDR) in the sorghum varieties at different phenological stages. Regression analysis reflected a positive correlation between HUE and sorghum yield, while correlation analysis depicted the chlorophyll content of the crop as a major contributor to the biomass yield. Among all the varieties, HJ 541 exhibited superior performance under all salt levels in terms of germination, leaf area, chlorophyll content, and biomass yield and was found at par with HJ 513. However, further study is required to elucidate the molecular mechanisms including gene expression, proteomics, genomics and metabolomics underlying salt tolerance in fodder sorghum.