Abstract
Varietal differences in growth, dry matter production and solar radiation interception among 11 peanut cultivars were studied under field conditions for 2 years to elucidate the salient features augmenting productivity. The cultivars used were Chiba 43, Chibahandachi (Virginia types) ; Kintoki, Hakuyu 7-3, (Spanish types) ; Valencia, Hotakuchuryu, Tarapoto (Valencia types) ; and Nakateyutaka, Kanto 56, Tachimasari and 334A (crossing types derived from crossing Spanish with Virginia types). The crossing types had early onset of pod formation with greater dry matter in the pods. Valencia, Chiba 43 and Tarapoto had late pod formation with most assimilates in their vegetative parts. In the initial growth period, the crop growth rate (CGR) was dependent on the leaf area index (LAI) ; in the late growth period the CGR was dependent on the net assimilation rate (NAR) and the pod growth rate (PGR) depended on the NAR. There was a highly negative correlation between the NAR and the LAI indicating the existence of severe mutual shading. The optimum LAIs ranged from 3.2 to 4.0. Intercepted radiation per unit LAI was higher in Tachimasari and Kanto 56 and lower in Chiba 43. From these results, the early development of larger leaf areas as in the Virginia types ; early sink development, higher percentage of pod dry weight and interception efficiency in the crossing types ensured higher dry matter production.
