Plant Type and Dry Matter Production in Peanut (Arachis hypogaea L.) Cultivars

I. Varietal differences in dry matter production

ABOAGYE Lawrence Misa, Akihiro ISODA, Hiroshi NOJIMA, Yasuo TAKASAKI, Takao YOSHIMURA** and Toshio ISHIKAWA** (Faculty of Horticulture, Chiba University, Matsudo-city, Chiba 27l, Japan , **Remote Sensing and Image Research Center, Chiba University, Yayoi-cho /-33, Inage-ku, Chiba-city, Chiba 263, Japan)

Abstract : Varietal differences in growth, dry matter production and solar radiation interception among I l 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.

Key words : Dry matter production, interception. Growth analysis, Optimum leaf area index, Peanut, Plant type, Radiation