Abstract

                                Mucuna pruriens an ayurvedic medicinal plant was studied for time of sowing at Tamil Nadu Agricultural University, Coimbatore, India from August 2003 to July 2004. The treatments were ten different month of sowing from August ’03 to July ’04. Days required for germination, flower initiation, 50 percent flowering and final harvest were recorded. Heat units such as Growing Degree Days (GDD), Photo Thermal Units (PTU), Helio Thermal Units (HTU), Relative Temperature Disparity (RTD), Relative Humidity Disparity (RHD) and Seasonal efficiency were worked out for different sowing months. The results revealed that, there was positive relationships between heat units like GDD/PTU/HTU at 50 percent flower initiation and DMP/yield/Harvest Index (HI), whereas it was negative between RTD/RHD and yield. The mucuna which received 50 per cent of its total accumulated heat units before its 50 per cent flowering did yield heavily (June to Aug). The mucuna which received higher accumulated heat units during its earlier stages had attained the flower initiation and 50 percent flowering stage earlier and the extended post flowering duration resulted in increased yield. It could be concluded that, relatively higher seed yield can obtained from June sowing and the mucuna require more accumulated heat units during its flowering phase for higher yield.

Key words : Heat Units, GDD, mucuna, yield.