UQ eSpace

Abstract

The purpose of this study was to identify physiological factors which would explain groundnut (Arachis hypogaea L) responses to plant population density and thinning during reproductive growth as a contribution to an understanding of the physiology of growth and yield. Four field experiments were conducted in three seasons (1987/88, 88/89 and 89/90) at the University of Queensland Redland Bay Farm (27° 37' S) in southeast Queensland, Australia. Leaf area index (LAI), interception of photosynthetically active radiation (PAR), total dry mass (TDM), dry mass (DM) partitioning, kernel yield and yield components were monitored in all experiments. The first experiment examined effects of plant population density in square arrangement on growth and yield in groundnut. Six lines, viz. three Virginia types (Improved Virginia Bunch, NC7 and Q18801) and three Spanish types (TMV-2, McCubbin and Red Spanish), were grown in plant population densities of 6.3, 11.1, 25.0 and 100.0 plant m-2. Total DM and economic yield were maximised at 25 plant m-2 in all lines, as were radiation use efficiency (Ec) and DM partitioning to pods during reproductive growth. At maturity, variation in economic yield depended on kernel harvest index (HI), partitioning index (PI), pod growth rate (PGR) and the yield components, ratio of pod number to peg+pod number, kernel number per pod and kernel size. The second experiment was aimed at determining if the optimum plant population density in Experiment 1, was influenced by plant arrangement. Two cultivars, Improved Virginia Bunch and Red Spanish, were grown at four plant population densities of 10, 21, 28 and 42 plant m-2 in rows, spaced 0.6 m apart. Maximum TDM and economic yield were attained with 21 plant m-2 in both cultivars.