Effect of artificial defoliation during different crop growth stages on yield losses of Spanish groundnut (Arachis hypogaea)

Abstract

Field trials were conducted during post rainy seasons of 2005 and 2006 to study the impact of insect simulated artificial defoliation on 'GG 2' Spanish groundnut (Arachis hypogaea L.). Four different defoliation levels were tested, i e no defoliation (treated it as control), 2,5, and 10 %*at different phenophases of crop, such as vegetative, pegging, podfilling and their combinations. Results indicated that groundnut pod yield was significantly affected by artificial defoliation during all the growth stages and their combinations except during 2 % defoliation during vegetative stage. Pod yield decreased with increase in intensity of artificial defoliation and in advanced stages of the crop growth. Pod yield was lowest (909.9 kgiha) when the plants were defoliated (10%) during pegging + pod filling stage. However shelling out turn, oil content and per cent sound mature kernels did not vary because of defoliation treatments. The reduction in yield because of simulated defoliation was due to the indeterminate nature of crop growth and competition for the photosynthates between the vegetative and reproductive parts. In this process of competition, plant tried to compensate the loss of foliage because of simulated defoliation and produced more foliage that affected the partitioning of photosynthates to reproductive parts and thus yields.