The pod shattering resistance of soybean lines based on the shattering incidence and severity

The study is aimed at evaluating the pod shattering resistance of F8 soybean lines based on the shattering incidence and shattering severity. The materials consist of fourteen F8 soybean lines and two check cultivars. The pod shattering incidence was examined by using the oven-dry method, meanwhile, the shattering severity was evaluated based on the severity of the pod opening. The pod shattering resistance based on the shattering incidence resulted in five resistant lines (7–10% shattering), seven moderate lines (13–23% shattering), one susceptible line (53% shattering), and one very susceptible line (100% shattering). The pod shattering resistance based on the shattering severity showed that the pod opening on the ventral side differed between the lines and between the shattering degree, and it tends to form sigmoid curves with a different peak position for each shattering degree. The shattering severity of the resistant, moderate, and susceptible lines reached a peak at 60 °C, 50 °C, and 40 °C, respectively. A longer pod length indicated by the length of the dorsal (r = 0.827**) and ventral (r = 0.880**) sides of the pod, a higher total pod weight (0.827**), and a larger seed size (0.794**) will increase the degree of susceptibility to pod shattering. Those characteristics were considered to be the ones that should be used as the selection criteria in the breeding programme for pod shattering resistance in soybeans.