Implications of daylength sensitivity in bambara groundnut (Vigna subterranea) for production in Botswana

Abstract

SUMMARYBambara groundnut (Vigna subterranea (L.) Verde.) is grown throughout southern and western Africa, primarily as a subsistence crop, but agronomic information is scarce. The rates of emergence, flowering and pod production were assessed for 20 weekly sowings between 16 October 1990 and 26 February 1991 at Sebele, Gaborone, Botswana. Daylength during this period changed from 12·7 h to 13·7 h and back to 12·6 h. Mean time to 50% emergence was 111 days while mean time to 50% flowering was 47·5 days. The thermal time to first pod production varied with daylength, decreasing as daylength decreased, to an approximately constant value when daylength after flowering was less than about 12 h. Consequently, the plant size at which pods were produced also varied. The practical implications for date of sowing and plant spacing are discussed.