Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2005
Publication Date: 3/15/2006
Citation: Chen, Y., Nelson, R.L. 2006. Variation in early plant height in wild soybean. Crop Science. 46(2):865-869. Interpretive Summary: Plant height at maturity is a commonly measured and important trait for soybean varieties. It is difficult to measure final plant height in wild soybean because there is often not a single main stem and the stems are very viney. We observed large variation in early plant growth among different wild soybean lines and designed this experiment to determine if those differences where repeatable in different environments. Our research found very large differences in the early plant height of wild soybean lines and that these differences were not related to final time of maturity. Averaged over replicated plants for two years, the shortest plants grew less than 9 inches when measured 30 days after planting whereas the tallest plants were over 36 inches tall. During the first 20 days the daily growth rates of the tall plants were more than 3 times greater than the short plants. Between 30 and 40 days after planting the daily growth rates were nearly identical. This rapid early growth trait in wild soybean could be beneficial if transferred to cultivated soybean. These results will be useful for soybean germplasm curators who are acquiring and maintaining genetic diversity and for soybean breeders who are utilizing that diversity.
Technical Abstract: Plant height at maturity is a common trait evaluated in soybean (Glycine max [L.] Merr.) germplasm. It is difficult to evaluate wild soybean (Glycine soja [Sieb. & Zucc.]) accessions for this trait because of the viney nature of the stem. In 1999, large differences were observed in plant height thirty days after planting among wild soybean accessions grown at Urbana, IL. No research about plant height at early growth stages has been reported for wild soybean. The objective of this study was to identify variation for plant height at early growth stages in wild soybean accessions. In 1999, plant height was measured on 468 wild soybean accessions in maturity groups 000 to IV thirty days after planting. Five accessions were selected within each of three maturity groups (00, II and IV) to represent three height classes, tall, intermediate and short, based on the data collected in 1999. These 45 accessions were planted in a completely randomized design with six replications in 2000 and 2003. Three height measurements (H1, H2, and H3) were taken at 10 day intervals beginning 20 days after planting. An analysis of variance (ANOVA) was conducted to evaluate the differences among maturity groups and early plant height classes. A multiple comparison T-test by Fisher’s Least Significant Differences (LSD) was used to test the differences among means of three early plant height classes. Highly significant differences were found among year, height classes, accessions within height classes and within maturity groups, and year by accession interactions for H2 measurement, but there were no significant differences among maturity groups and no interaction between year and height classes. The optimal time for evaluating differences in early plant height is thirty days after planting. This rapid growth trait in wild soybean could be beneficial for cultivated soybean and a useful trait for evaluating wild soybean germplasm.