Environmental Adaptation of Long-Juvenile Soybean Cultivars and Elite Strains
- Jeffrey P. Tomkins and
- Emerson R. Shipe
A long-juvenile (LJ) trait that delays flowering under short-day conditions has been incorporated into adapted soybean [Glycine max (L.) Merr.] germplasm. Little is known about the performance of recently developed LJ cultivars and elite strains as influenced by planting systems typical of the southeastern USA. Therefore, a field study was undertaken using two LJ cultivars and four elite LJ Florida strains at Blackville and Pendleton, SC. Planting dates were early (late April), normal (late May), and late (late June), in 1993 1994. The LJ genotypes exhibited neither genotype × planting date nor genotype × location interactions for seed yield or seed quality, indicating consistency of genotype performance across environments. Although variation among LJ genotypes for yield was not detected, all four elite strains all ranked higher in yield than the two cuitivars. Maturity varied among LJ genotypes but seed yield did not, indicating the possibility of developing LJ genotypes that have relatively short life cycles and high seed yield. Additionally, LJ genotypes were compared with two conventional cultivars: Maturity Groups (MG) IV, and VI at early plantings; MG V, VI, and VII at normal plantings; and MG VI, VH, and VIII at late plantings. As planting date was delayed, growth and agronomic responses of LJ genotypes became similar to those of successively later conventional cnitivars. The LJ genotypes were similar in yield to conventional cultivars in maturity groups V to VIII across planting dates, but had 56% higher yields than MG IV cultivars at the early planting. Seed quality ratings of LJ genotypes were 54 and 23% better than MG IV and V cuitivars, respectively, at the early planting. In general, LJ genotypes showed superior photoperiodic adaptation to different planting date environments.
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