Physiological Aspects of Peanut Yield Improvement¹

Abstract

Development of new peanut ( Arachis hypogaea L.) cultivars over the past 40 years has more than doubled yield potential. The purpose of this paper is to identify and evaluate the physiological changes made in the course of this varietal improvement that are responsible for the great increase in yield potential. Weekly harvests of large samples of four Florida cultivars, a Spanish peanut type, and one soybean ( Glycine max (L.) Merr.) cultlvar gave the information needed to show the progressive changes in dry weights of all plant parts throughout the growing season. Other weekly samplings and observations gave numbers of pegs, flowers, and fruits as well as fruit weights, root length, shoot length, and leaf areas. Quantitative estimates of the physiologlcal factors responsible for the dry weight differences were made by computer simulation using the PENUTZ model. Differences in three physiological processes explain most of the yield variation among the five peanut cultivars; the partitioning of assimilate between vegetative and reproductive parts, the length of the filling period, and the rate of fruit establishment. Of these, the partitioning of assimilate had the greatest effect on fruit yield. Estimates of partitioning to fruit ranged from 41% in the first cultivar released to 98% in the most recently released cultivar. Crop growth rates did not differ significantly among peanut cultivars but all were much higher than the crop growth rate of soybeans.