Genetic Variation for Seedling Traits in Hydroponics and Correlated Response with Mature Plant Traits on Acid Soil Field

Four levels of aluminium activity (0, 5, 50 and 300 μMAl3+) were used to screen soybean seedlings in hydroponics for 3 days (3D) and 13 days (13D). The objective of the research was to determine genetic variation for aluminium stress tolerance in seedlings (primary root length, root and shoot dry weight) and to correlate the hydroponics result with that of mature plants on acid soil field. The four levels of aluminium activity constituted the main plots while 49 soybean genotypes constituted the subplots in a split-plot design, with three replications in both 3D and 13D. Genetic variance was higher than other variance components, leading to moderate to high heritability estimates (56.16 – 92.52%) for aluminium stress tolerance in both 3D and 13D hydroponics media. Genetic Coefficient of variation (GCV) ranged from a very low value of 1.88% for shoot dry weight in 13D hydroponics media to a very high value of 116.39% for primary root length in the 3D hydroponics media with higher phenotypic coefficient of variation (PCV) in 3D and 13D. The GA for primary root length was high in 13D (95.30%) and very high in 3D (187.37%) compared to very low values (2.71 – 9.01%) observed for the root and shoot dry weights in both 3D and 13D hydroponics media. Significant and highly significant positive correlations were observed between most of the seedling traits in 3D and 13D and between the hydroponics and acid soil field in general. The results of the current study indicate that aluminium stress tolerance in tropically adapted genotypes of soybean is heritable and that there is sufficient genetic variation for selection of seedling traits of the studied population in hydroponics. The results of correlation also implies that a two – stage selection process, beginning with selection of tender seedling root traits at 50/300 µMAl3+ in 3D, to be subsequently followed by selection for root dry weight at 0 µMAl3+ in 13D prior to acid soil field evaluation. Further studies on the activity of manganese and iron on the growth and development of soybean in the presence and absence of aluminium is required.