Brachytic Stem and Narrow Leaflet Effects on Soybean Seed Composition and Yield

Abstract

Soybean [Glycine max (L.) Merr.] seed protein and oil concentrations and their interrelationships with seed yield are important considerations in a soybean breeding program. Brachytic stem and narrow leaflet traits were transferred to a ‘Tracy‐M’ background to evaluate their effect on seed yield and concentration of seed protein and oil. Data were collected oil eight brachytic stem (sb) lines, eight narrow leaflet (In)lines, seven lines with the combination (sb, In) of traits, and the recurrent parent, Tracy‐M, from 1986 through 1988 at Stoneville, MS, on a Sharkey clay soil (very‐fine, montmorillonitic, nonacid, thermic Vertic Haplaquept). Seed protein and oil concentrations were determined by near infrared reflectance. Combined over years, Tracy‐M had a seed yield of 2612 kg ha−1. Seed yields of the sb, sb In, and In groups were 2352, 2213, and 2361 kg ha−1, respectively, and were significantly (P ≤ 0.01) lower than that of Tracy‐M. Seed protein concentration of the sb, sb In, and In groups were 441, 444, and 426 g kg−1, respectively, and were all significantly (P ≤ 0.01) different from the 432 g kg−1 protein concentration of Tracy‐M. Only the sb In group had an oil concentration that was significantly (P ≤ 0.01) different from that of Tracy‐M. The reason for the significantly higher seed protein concentration of brachytic lines over that of the recurrent parent Tracy‐M is unknown. None of the ancestors used in the development of the experimental lines has a seed protein concentration as high as that of Tracy‐M.