Physiology of bunch groundnuts (Arachis hypogaeaL.)

Abstract

SummaryTwenty-nine bunch groundnut genotypes were grown in theKharifseason 1980 and the summer season 1981 at Bangalore. Growth and yield analysis showed that the total dry-matter accumulation was low up to 30 days after sowing and increased linearly up to the 86th day in theKharifand up to harvest in the summer season. There were significant differences between genotypes in leaf area indices (LAI), the leaf area duration (LAD) and LAD between pod initiation and harvest (LADP) in both the seasons. The mean LAI of genotypes did not vary much between theKharifand the summer seasons up to the 66th day. However, during the later stages of growth the LAD was higher in the summer. The higher biological yield and productivity in the summer was attributed to the high LAD and LADP during the later stages of crop growth. LAD and total dry-matter accumulation at harvest were significantly correlated both in theKharif(r = 0–75) and the summer(r= 0–81). The mean total number of flowers over all 29 genotypes did not vary, but total number of pegs formed per plant differed significantly between genotypes in both theKharifand summer seasons. The percentage of flowers which produced pegs was 72–2 in summer as against 51–2 inKharif.The primary branches contributed 86'7 and 90–1%to the total number of pods per plant in theKharifand summer seasons respectively. The contribution of the first four nodes of primary branches was 85%in both seasons. The number of fruiting points (nodes having mature pods) per plant, found to be the most important yield-determining component, showed significant variation amongst the genotypes in both theKharifand summer seasons. In summer, length of mature-pod-bearing zone (MPBZ), number of nodes in MPBZ and number of kernels per plant were higher than in theKharifseason. It is suggested that selection and breeding should concentrate on improving LAD and LADP, total dry matter per plant, more primary branches per plant, more pods in the distal nodes of primary branches and more fruiting points (nodes in MPBZ) per plant.