Soybean Seed Growth II. Individual Seed Mass and Component Compensation1

Abstract

abstractSince the rate and duration of the growth of individual seeds determine final seed mass, a detailed study of these variables with respect to morphological position on individual soybean [Glycine mar (L.) Merr.] plants was undertaken. A predictable pattern of seed growth could lead to explanatory models for crop yield. Plants were grown under field conditions at Ithaca, N.Y. (soil was a fine, illitic, mesic, Glossaquic Hapludalf) and Gainesville, Fla. (soil was a loam‐siliceous, hyperthermic, Grossarenic Paleudalf). To determine the influence of morphological position on individual seed mass, rate and timing of dry matter accumulation of individual seeds at various positions on individual plants were determined from detailed observations of the initiation and termination of seed growth. multiple linear regressions of final individual seed mass on duration and position variables did not consistently account for the variation in seed size. Also, the rate of seed growth was not consistently related to easily observed properties of the plants. No pattern was identified upon which an explanatory model of seed yield could be based. The degree of compensation between mean mass per seed and seed number was determined for individual plants within a cultivar. When individual plants were first grouped according to total plant mass, mean mass per seed was negatively correlated with seed number. Estimates of component compensation which do not take into account the variation in plant size are likely to underestimate the degree of negative correlation.