Heat Units Requirement and Heat Unit Efficiency of Parental Lines and their Hybrids in Rabi Sorghum

The experiment was laid out in split plot design with three replications during rabi 2013–14 at All India Co-ordinated Sorghum Improvement Project, Mahatma Phule Krishi Vidyapeeth, Rahuri, Dist. Ahmednagar (M.S.). Seven sowing dates were assigned to main plot and 16 parental lines with four male sterile and their maintainers and four restorer and their four respective hybrids were assigned to sub plot treatment. The observations on phenology, dry matter production and grain yield were recorded. The heat unit and heat unit efficiency were computed as per the standard formulae. From results the lowest heat units accumulated from sowing to panicle initiation, 50% flowering to maturity and sowing to maturity was recorded at September sowing date. The highest heat unit efficiency (HUE) for dry matter production and grain yield were recorded during October sowing date. Among the parental lines and hybrids the hybrids 104 A X SPV 1830 and RMS 2010–10 A X BJV 116 were observed to be the most efficient in conversion of absorbed heat into dry matter production and grain yield, respectively.