Influence of the different pod positions and screening methods on soybean pod shattering

Pod shattering is one of the major soybean constraints in the soybean production centers, particularly in the tropics. The screening for pod shattering resistance of 16 genotypes was carried out using detached and undetached pod methods on the three different pod positions on the stem. The field research was arranged in a randomized block design, during the dry season in Banyuwangi, Indonesia. The shattering evaluation was conducted in the laboratory using the ovendry method. The screening methods to investigate the pod shattering resistance of each genotype consisted of the detached pod (DP), undetached pod (UDP), and undetached whole-stem method (UWS). The result showed that the detached pod method (DP) resulted in a higher average podshattering percentage (15%) than the undetached pod methods (UDP and UWS, 13% and 11%, respectively). Nevertheless, the detached pod and undetached pod methods provide a consistent result for the evaluation of pod shattering resistance, showed by their correlation coefficients (DP and UDP, r = 0.98**; DP and UWS, r = 0.98**, UDP and UWS, r = 0.99**). The detached pod with the oven-dry method was suggested to be used for screening of pod shattering resistance. This method enables to screen genotypes in greater numbers, provides a homogeneous selection pressure and environmental condition. Pods at the upper part of the stem were more resistant to shattering than those pods in the middle part and lower part. The pod length, seed length, seed weight, pod wall weight to the pod weight ratio, and weight of 25 seeds appeared to be the significant indicators for pod shattering resistance. The shattering evaluation resulted in five soybean genotypes (Anj/G100H-28, Anj/G100H-44, Anj/Rjbs-304, Anj/Rjbs-30, and Detap 1) with consistent resistance to pod shattering based on the three methods. These genotypes can be used as donor parents in the breeding program for pod shattering resistance.