Factorial combinations of four photoperiods (10, 11·33, 12·66 and 16 h d-1) and three mean diurnal temperatures (20·2, 24·1 and 28·1°C) were imposed on nodulated plants of three Nigerian bambara groundnut genotypes [Vigna subterranea (L.) Verdc., syn. Voandzeia subterranea (L.) Thouars] grown in glasshouses in The Netherlands. The photothermal response of the onset of flowering and the onset of podding were determined. The time from sowing to first flower (f) was determined by noting the day on which the first open flower appeared. The time from sowing to the onset of podding (p) was estimated from linear regressions of pod dry weight against time from sowing. Developmental rates were derived from the reciprocals of f and p. In two genotypes, 'Ankpa 2' and 'Yola', flowering occurred irrespective of photoperiod and 1/f was controlled by temperature only, occurring sooner at 28·1 than at 20·2°C. The third genotype, 'Ankpa 4', was sensitive to temperature and photoperiod and f was increased by cooler temperatures and photoperiods > 12·66 h d-1 at 20·2°C and > 11·33 h d-1 at 24·1 and 28·1°C. In contrast, p was affected by temperature and photoperiod in all three genotypes. In bambara groundnut photoperiod-sensitivity therefore increases between the onset of flowering and the onset of podding. The most photoperiod-sensitive genotype with respect to p was 'Ankpa 4', followed by 'Yola' and 'Ankpa 2'. There was also variation in temperature-sensitivity between the genotypes investigated. Evaluation of bambara groundnut genotypes for adaptation to different photothermal environments will therefore require screening for flowering and podding responses.
Linnemann, A.R.; Craufurd, P.Q. Effects of Temperature and Photoperiod on Phenological Development in Three Genotypes of Bambara Groundnut (Vigna subterranea). Annals of Botany (1994) 74 (6) 675-681. [DOI: 10.1006/anbo.1994.1170]