Peanut yield and quality variation over harvest dates, and evaluation of some maturity indices in south-eastern Queensland

Abstract

Yield and quality variations across harvest dates in peanuts (Arachis hypogaea L.) grown under rainfed conditions in south-eastern Queensland in 1978-79 and 1980-81 were investigated. Free arginine percentage of kernels, kernel: hull weight ratio, shell-out percentage, mean individual kernel weight and kernel moisture percentage were monitored during crop development to assess their usefulness as indices of crop maturity. For the Virginia Bunch cultivar, kernel yield ranged from 1862 kg ha-1 at 133 days after sowing (DAS) to 2432 kg ha-l at 168 DAS in 1978-79 and from 687 kg ha-l at 201 DAS to 1618 kg ha-1 at 152 DAS in 1980-81. In both years kernel yield and crop value for Virginia Bunch exhibited bimodal responses to delayed harvesting, with maximum values being obtained at about 150 and 170 DAS. These responses tended to be associated with rainfall distribution and available soil moisture during flowering. None of the maturity indices investigated was sensitive enough to detect the 2 peaks for yield or crop value and therefore would be of no use in determining optimum harvest periods for Virginia Bunch. Red Spanish and White Spanish cultivars, evaluated in 1978-79, produced average kernel yields of 1777 kg ha-l and 1535 kg ha-1 respectively. For these cultivars, differences in yield and crop value over harvest dates were not significant. Although kernel yields did not increase after 133 DAS, the decline in free arginine percentage and the increase in the kerne1:hull weight ratio during the season suggested that these indices may be useful indicators of optimum maturity for spanish-type cultivars.