Thermal requirement of kharif crops under rainfed condition in north Saurashtra of Gujarat

The experiment was conducted to determine thermal requirement of short (Sesame: Guj. Til-2, Black gram: T-9, Pearl millet: GHB-558) and long duration crops (Cotton: G Cot-Hy-8, Castor: GCH-6, Groundnut: GG-13) at the Dry Farming Research Station, Junagadh Agricultural University, Targhadia, (Dist: Rajkot, Gujarat, India) at north Saurashtra agro climatic zone – VI during kharif seasons of 2008-2010. The experiment was laid out in a sampling techniques and plot size was gross: 4.5m x 3.6m and net: 2.7m x 1.8m. The objectives of the experiment were to find out meteorologically suitable date of sowing, to calculate thermal requirement as well as heat use efficiency of the crops. The two years results revealed that the highest growing degree days (GDD), photo thermal units (PTU), heat use efficiency and yield for sesame, black gram, pearl millet and spreading groundnut were recorded during first date of sowing. For cotton and castor crops the two years results showed that the highest growing degree days (GDD), heliothermal units (HTU), photo thermal units (PTU), heat use efficiency and yield recorded under first date of sowing. It means first date sown crop utilized higher thermal / heat energy. Thus, delay in sowing resulted in declined yield in cases of both short and long duration kharif crops.