Heat unit requirement of field grown groundnut varieties

Abstract

Field investigation was carried out to study the effect of temperature on the phenology of groundnut varieties during summer and kharif seasons at two locations. VRI 3 and TMV 7 attained maturity in 101 and 108 days in Thiruchengode and VRI 2 attained maturity in 112 days in Avinashi. The growing degree days and photo thermal units required from sowing to 50 per cent flowering and 50 per cent flowering to maturity phenophases were worked out. The average value of accumulated GDD from sowing to maturity was 2303°C days with co-efficient of variation of 11 per cent and photo thermal units are 27779°C day hours with the co-efficient of variation of 11 per cent in Thiruchengode. For Avinashi, the same phenophase required ac- cumulated GDD of 2161°C days with co-efficient of variation of per cent and photo thermal units are 26012°C day hours with the co-efficient of variation of per cent. Two linear regression models were derived based on the phenophase-wise data pooled over different varieties across the locations for predicting the onset of maturity phenophase of the crop using either growing degree days or photo thermal units. Onset of particular phenophase depended upon the available growing degree days or photo thermal units which accounted for 94 per cent of the total variation.