Fruit maturity, storage and postharvest maturation treatments affect bell pepper ( Capsicum annuum L.) seed quality

Abstract

Some peppers ( Capsicum sp.) exhibit a primary seed dormancy at harvest. This study was designed to examine the effect of fruit maturity, dry and moist seed storage and seed postharvest maturation treatments on the seed germination of four bell pepper cultivars ( Capsicum annuum L., cultivars ‘Early Calwonder’, ‘Resistant Giant No. 4’, ‘VR2’ and ‘Yolo Wonder’). In 1987 and 1988, fruits were harvested 30 (mature green), 40 (breaker), 50 (mature red) and 60 (over-mature red) days postanthesis (dpa), and seeds were extracted for dry storage treatments, or allowed to remain in fruits for postharvest maturation treatments of 0, 7, 14, 21 and 28 day periods. In 1988, seeds were also stored over water or saturated salt solutions which provided relative humidities of 7, 51 and 97.5% to determine the influence of seed moisture during seed storage. Seeds from red and over-mature red (50 dpa and 60 dpa, respectively) fruit generally had greater dry weights and higher germination percentages relative to seeds from less mature fruits. Seeds extracted from mature green (30 dpa) fruit did not germinate regardless of storage time. Seed postharvest maturation of up to 14 days in green fruit significantly increased seed germination in all cultivars. When pepper seeds were allowed to remain in mature red (50 dpa) fruit for various postharvest maturation periods, germination percentages were generally significantly greater than in dry storage and mature green (30 dpa) postharvest maturation treatments. Starch concentrations of ‘Resistant Giant No. 4’ seeds increased from 10 to 80 mg glucose per 100 g dry wt. when seeds remained in fruit for 4 weeks after harvest. Dry storage of seeds following extraction from red fruit did not significantly increase germination, indicating that seed afterripening did not occur. Short storage periods (7 and 14 days) at low relative humidity (7 and 51%) significantly improved seed germination of ‘Early Calwonder’ and ‘Resistant Giant No. 4’. Storage for 7–14 days of ‘Early Calwonder’ and ‘Resistant Giant No. 4’ seeds at high (97 and 100%) relative humidities was also beneficial, but at longer periods germination percentages of all cultivars dropped. There were few significant differences in seed dry weight between dry storage and postharvest maturation treatments. It is possible that in situ priming may have occurred in 30 and 50 dpa seed postharvest maturation treatments. These results suggest that following fruit harvest, pepper seeds should remain in red (50 dpa) fruit for a short postharvest maturation period to achieve maximum seed germination potential.