Root traits correlated with soybean yield in a subtropical region

Root system plays a crucial role in plants' anchoring, water and nutrients acquisition and storage of carbohydrates. While it is understood that root system traits contribute to crop yield, little is known about the particular effects of root morphology over crop yield, even on major crops such as soybean (Glycine max). The objective of this study was to investigate if distinct soybean grain yield plants, grown at different sites, displayed differences in their root system morphology. This distinct traits in the root system should be responsible to the differences of yield, thus, showing which traits should be followed in breeding programs to develop higher yield cultivars. The soybean cultivar DM 5958 RSF IPRO was sowing in a randomized complete block design experiment. Treatments comprised three cultivation sites and five soybean grain yield classes. Plant emergence and root system morphology attributes were evaluated. Results showed that late emergence negatively influenced root development. A huge difference among sites over very thin (89%) and thin (85%) roots was found in the high yield class, and since the plants have similar yield, it appeared that the thin and very thin roots length have no impact on the yield, being influenced mostly by the environment. Forks and tips roots didn't show a pattern. In contrast, roots volume only showed a 22% reduction, demonstrating to be less influenced by the environment, resulting in a greater correlation with the grain yield. Thus identified as the main attribute to be explored when seeking to select new soybean cultivars.