Monday, June 18, 2007
Identification of Selectable Growth Traits in Soybeans at High Plant Density.
Y.J. Oh1, K.H. Kim1, H.K. Park1, J.G. Kim1, J.H. Ryu2, A.J. Wood3, and Y. Cho4. (1) Honam Agricultural Research Institute, Iksan, Jeonbuk, 570-080, South Korea, (2) Chonbuk National University, Jeonju, Jeonbuk, 561-756, South Korea, (3) Southern Illinois University, Department of Plant Biology, Center for Excellence in Soybean Research, Teaching and Outreach, Carbondale, IL 62901, (4) Eastern New Mexico University, Department of Biology, Portales, NM 88130
The late planting of double crop soybeans at high plant density affects plant growth during both vegetative and reproductive stages resulting in a loss of seed yield. The objectives were to examine genetic and growth variation at high plant density and to determine favorable growth traits as a selection index for the development of primary breeding criteria. Five soybean genotypes: Camp, Eunhakong, HS 287, Iksannamulkong, and Pureunkong, were used in field experiments conducted over three years. Lodging was significantly (P < 0.05) and positively correlated with main stem length, internode length, and branch angle, but negatively correlated with number of pods on the main stem and harvest index. Yield was significantly (P < 0.05) dependent upon the number of pods per plant and number of pods on the main stem. Highly weighted variables under the first principal component, which explained 49.2 % of the total variation, included internode length, lodging, and number of pods on the main stem. The second principal component explained an additional 23.5 % of the total variation. These two components explained 72.7 % of the total variation in all the variables. The coefficient of determination (R2 = 0.88) from the multiple linear regression analysis with four key variables (internode length, branch angle, lodging, and number of pod on the main stem) indicates these growth traits causally responded to high plant density along with the short growing season.