Effect of drought during early reproductive development on the dynamics of yield development of cultivars of groundnut ( Arachis hypogaea L.)

Abstract

In a glasshouse experiment, cultivars of groundnut ( Arachis hypogaea L.) were grown well watered throughout or were grown well watered except when water was withheld for a period of 3 weeks during either of two periods during early reproductive development. When water was withheld from 46 to 67 days after sowing (DAS), Robut-33, the cultivar with the highest harvest index (HI), produced a greater yield than either Virginia Bunch or McCubbin. This was attributed to the maintenance of a relatively higher number of pods, compared to the other cultivars. When water was withheld from 61–78 DAS, the Virginia type cultivars (Virginia Bunch and Robut-33) produced a greater yield than the Spanish type cultivar (McCubbin). Frequent observations were made of the appearance and elongation of pegs in all treatments. Peg initiation was sensitive even to mild water deficit, but elongation of pegs halted by water deficit could continue after rewatering. This may be an important attribute particularly where intermittent drought occurs. In both water-deficit treatments, peg initiation and elongation in all cultivars halted after about 80% of the extractable soil water had been exhausted. The yield advantage of Robut-33 was mainly in producing a large number of pods prior to water deficit, and in partioning a greater amount of biomass to pods after rewatering. The Virginia type cultivars were also apparently better able to tolerate the effects of severe water deficit. While only three cultivars were examined in this glasshouse experiment, the performance of Robut-33 points to the usefulness of highly synchronous development (generally a Spanish type characteristic) and high HI as well as an ability to tolerate drought in groundnut cultivars exposed to water deficits during early reproductive development.