Physalis ixocarpa physiological seed quality in terms of maturity at harvest and storage conditions

Abstract

Seed deterioration during storage reduces germination and seedling establishment in the field. For Physalis ixocarpa Brot. seeds the levels of environmental factors that affect its germination longevity and physiological performance during storage, depending on the state of development at harvest are unknown. For this research, variety Chapingo seeds harvested at three stages of development were evaluated (45, 55 and 65 days after pollination), in three storage periods (0, 4 and 8 months) combined with five environments including two temperatures (23.8 and 5.3 °C) and two relative humidity levels (24 and 81%). It was found that, the seeds can maintain its initial germination capacity (70%) for at least 8 months when stored under low relative humidity (24%) or cold (5 °C), since the combination of high relative humidity (81%) and temperature of 23 °C cause degradation in the seeds. The deterioration is manifested in reduced germination from 70 to 29%, viability from 81 to 46%, radicle rate of emergence from 20.4 to 9.9 radicles per day, rate of emergence of the aerial part from 6.3 to 2.3 seedlings per day, respiration from 16.1 to 6.6 nmol CO2 g-1 s-1 and an increase in electrical conductivity from 32 to 97 μS cm-1 g-1. Seeds of 55 days of age have already reached physiological maturity, since they germinate with the same vigor that the seeds of 65 days. Immature seeds of 45 days do have ability to germinate, although 10% less than mature seed and with less vigor.