Optimization of Sowing Window for Summer Fodder Sorghum Cultivars by Thermo Radiation Requirements Under Southern Agroclimatic Zone of Andhra Pradesh in India

Field experiment was conducted during summerseason,2018 on sandy loam soils of dryland farm of S.V. Agricultural College, Tirupati, Acharya N.G. Ranga Agricultural University to study radiation use efficiency of fodder sorghum crop. The experiment was in four times of sowing viz., I FN of January, II FN of January, I FN of February and II FN of February with three fodder sorghum varieties viz., CSV 21 F, CSV 30 F and CSV 32 F. Efficiency of thermal and radiation energy conversion into dry biomass was computed using thermal and radiation indices.Results obtained during study revealed that early planting of crop CSV 32 F resulted in higher thermal use efficiency and radiation use efficiencies with higher fodder yield compared to delayed sowings. The correlation studies between RUE and TUE to LAI, dry matter accumulation and green fodder yield showed at significant positive linear relationship. The regression coefficients between meteorological indices viz., RUE and TUE and crop parameters viz., LAI, dry matter production, green fodder yieldwere significantly influenced by varieties at varied times of sowing. Conversion efficiency of radiation and thermal energy to accumulation of dry matter varied much with times of sowing and varieties.