Evaluation of light extinction coefficient, radiation use efficiency and grain yield of soybean genotypes

This experiment was performed at the Research Center of Agriculture and Natural Resources, Ardabil, province (Moghan), Iran, in 2009 and 2010. Light extinction coefficient, radiation use efficiency, yield and yield components of 17 soybean genotypes were evaluated. Number of seed per plant was significantly affected by years. In both years, all traits among genotypes were significantly different. In both years, the highest number of seed per plant was obtained from Apollo genotype. Omaha and NE-3399 genotypes had the highest seed weight in the first and second years respectively, whereas L.83-570 genotype produced the lowest value for this trait in both years. The highest yield in the first year (351.3 and 349.8 g m-2) were obtained from Apollo and Ks-4895 genotypes, respectively, while in the second year, Zane genotype produced the highest yield. In both years the lowest yield were derived from Rend and L.83-570 genotypes. The maximum (0.62 ± 0.084) and minimum (0.44 ± 0.034) value for coefficients of light extinction were obtained from Hsus-H116 and Apollo genotypes respectively. The highest radiation use efficiency (1.14 ± 0.134) was obtained from Darby, and the lowest (0.91 ± 0.152) from L.17 genotype. In general the Apollo genotype with respect to its low light extinction coefficient and high radiation use efficiency produced the highest grain yield.   Key words: Light extinction coefficient, radiation use efficiency, genotype, soybean.