Br. Ntare et al., Evaluation of groundnut genotypes for heat tolerance under field conditions in a Sahelian environment using a simple physiological model for yield, J AGR SCI, 136, 2001, pp. 81-88
Heat tolerance of groundnut (Arachis hypogaea L.) was evaluated under field
conditions using physiological traits identified in a yield model [crop gr
ow th rate (C). reproductive duration (D-r) and partitioning (p)], In 1991.
625 diverse genotypes were initially screened under irrigation during the
hottest months (February to Mag;). Subsequent tests consisted of 16 contras
ting genotypes selected based on a combination of high pod yield and partit
ioning coefficient of > 0.50. Large variation was observed among the 625 ge
notypes for pod yield and physiological traits. C was a powerful factor inf
luencing pod yield. Eight genotypes combining high pod yield and a partitio
ning coefficient greater than 0.6 were identified. These included two relea
sed cultivars (55-437 and 796) in the Sahel. Correlations between seasons w
ere significant for p (r = 0.84), but nun-significant For pod yield (r = 0.
40), C (r = 0.39), and D-r (0.36). Date of sowing and genotypes had signifi
cant effects on pod yield and C, but were slight on p and D-r. pod yield of
most genotypes declined by more than 50% when flowering and pod formation
occurred when maximum temperatures averaged 40 degreesC. The results reveal
ed that estimates of p would be a more reliable selection criterion for ide
ntification of genotypes tolerant to heat than yield. Further research is s
uggested to maximize crop growth rate and partitioning of genotypes growing
under supra-optimal temperatures.