Water deficit as a trigger to immature soybean pod opening

Abstract

AbstractRecently, the opening of immature and green pods has been identified in some soybean genotypes and it has raised concern. The cause of this opening has not been elucidated yet, but there is some evidence it may be associated with water‐deficit occurrences. Thus, this study aimed to verify the influence of water deficit on the opening of immature pods and correlate this feature with other agronomic traits. For this purpose, two trials using 99 soybean genotypes were carried out in a greenhouse. The plants were kept under two irrigation treatments: control treatment (soil kept at water potential of −33 kPa) and water‐deficit treatment (soil kept at water potential of −900 kPa, imposed between the R3 and R6 development stages). The number of immature open pods was analysed descriptively and we found that, in both trials, the water‐deficit treatment favoured the opening of immature pods of some genotypes. In trial 1, we evidenced that, under water deficit, grains tend to have greater volumes, and thus, the pod does not bear the size of the grain and shatters. In trial 2, in addition to water deficit, other factors acted on grain size and, consequently, on the opening of immature pods. According to the correlation analysis, the other evaluated agronomic traits did not behave in a consistent way in the two trials, and so they would not be recommended for the indirect selection of the opening of immature pods. Besides water deficit, other soil and climate factors might affect this process of immature pod opening.