Differences in seed germination of wild and domesticated common bean (Phaseolus vulgaris L.) in response to storage

Abstract

This study compared the effect of storage on the germination of wild and domesticated common bean (Phaseolus vulgaris L.). Two sizes (large and small) of intact and mechanically scarified seeds of wild common bean from Salti to, Durango and La Malinche, Tlaxcala, Mexico, and the cultivars Bayo Mecentral and Amarillo were stored at 300 and 75% RH for 0, 30, 60 and 90 days. Germination in the dark at 25C was evaluated. In general, mechanical scarification at zero days of storage induced a reduction in the time to the start of germination (5 to 83h) and in the time to complete germination (126 to 341h) of wild seeds, but it did not affect the percentage of germination. After 30d of storage the germination of small intact wild seeds from Tlaxcala and cv. Bayo Mecentral was reduced to 30%; but after 60d of storage, wild small seeds from Tlaxcala and both cultivars were almost 100% inhibited. In contrast, as an average, intact and scarified wild seeds from Durango and larger seeds from Tlaxcala reached 52 and 25% of germination respectively. Although 90d of storage affected drastically both wild and domesticated beans, even after this long storage, 3 to 15% of wild seeds germinated. The results are consistent with the speculation that an increased sensitivity of common bean seeds to storage under high temperature and elevated RH could be a concomitant result of selection for some other traits such as targe seed during domestication.