Seed development and maturation inPhaseolus vulgarisII. Post-harvest longevity in air-dry storage

Abstract

Changes in seed quality were monitored during the development and maturation of seeds of bean (Phaseolus vulgaris L.) in different environments by determining the subsequent survival of seeds in airdry storage. The seed survival curves (percentage normal germination plotted against period of storage) conformed to negative cumulative normal distributions, and the same seed storage environment (40 °C with 14% moisture content) provided the same estimate of the standard deviation of the frequency distribution of seed deaths in time for all the seed lots harvested at different times during development in the different environments (21.3 d and 20.9 d in 1993 and 1994, respectively). The potential longevity of developing seeds (quantified by the value of the seed lot constant of the seed viablity equation) continued to increase after mass maturity (end of the seed-filling phase). Maximum potential longevity was attained 23 d (30/24 °C, 1993), 13 d (30/24 °C, 1994), or 34 d (27/21 °C, 1994) after mass maturity, by which time seeds had dried naturally to 17% (30/24 °C, 1993), 18% (30/24 °C, 1994), and 16% (27/21 °C, 1994) moisture content. Seed quality was greater in the cooler temperature seed production regime because of an increased duration of seed quality improvement. The results show that maximum seed quality is not attained until some time after the end of the seed-filling phase in bean, and confirm that the slow desiccation that occurs after ovule abscission during natural maturation drying is beneficial to the development of seed quality in bean.