Genotypic Variation in Soybean Nodule Number and Weight

Environment and genetics influence the process of nodulation in soybean [Glycine max(L.) Merr.]. To select for increased N2fixation in soybean, plant breeders need to identify those morphological traits associated with the fixation process. The objectives of this study were to classify cultivars (Maturity Groups V through IX) and breeding lines for nodule weight, nodule number, and shoot and root weight at the R3 to R4 stage of development under field conditions in Gainesville, FL. Of the 100 soybean genotypes screened in 1983, 17 were selected for more detailed study in 1984 and 1985. ‘Hardee’, ‘Centennial’ and F81‐7313 ranked among the genotypes with the greatest nodule weight and number; and these rankings were consistent across years and locations tested. Environmental stability analyses showed that those lines with the greatest mean nodule weight also had the greatest positive response to favorable environments. Nodule weight and number were highly correlated traits (r> 0.84). Root and shoot weight had moderately positive correlations with nodule number and nodule weight.