Fruit maturity & after-ripening improve seed physical and physiological quality of Solanum aethiopicum L.

Abstract

In the absence of a reliable seed supply for the African eggplant (Solanum aethiopicum L.), farmers source their seeds from fruits harvested for fresh market (precocious harvests) but ripen later in the market. Some also source seeds from traders who extract seeds from unsold fruits. Fruits harvested at 20 days after anthesis (DAA) failed to germinate while those extracted from 34 DAA fruits had less than 10% germination in a preliminary study. This study was, therefore, conducted to determine whether the seeds within fruits harvested at 30 days after anthesis upwards could be after-ripened prior to seed extraction to improve seed physical and physiological quality characteristics. The treatments were laid in a randomized complete block design in a 2 x 5 x 4 factorial arrangement involving two cultivars, five harvest maturity stages: 30, 40, 50, 60 and 70 days after anthesis, four after-ripening periods: 0, 5, 10 and 15 days with four replications. Fruits were harvested at different maturity stages & seeds were extracted at 0, 5, 10 and 15 days of storage under ambient condition (24 ± 3°C) after each harvest. Seed dry weight, seed moisture content, 1000 seed weight, first germination count and germination percentage were determined. It was established that precocious harvest (30 days after anthesis, DAA) was not beneficial to physiological seed quality even when subjected to 15 days after-ripening. Fruits harvested 40 DAA failed to germinate while 50 DAA fruits had not more than 50% germination in both cultivars. However, when seeds extracted from these fruits were ripened for 15 days in storage, the germination percentage increased significantly by 63 to 72%. Seeds extracted from fruits harvested 60 or 70 DAA achieved the maximum germination, varying between 93 to 94% (cv. Oforiwa) & 78 to 96% (cv. Kpando) independent of after-ripening treatment. It is concluded that after-ripening is inconsequential & not necessary when seeds are harvested at physiological maturity (60 -70 DAA). For the purpose of seed production, it is recommended to harvest seeds of African eggplant at physiological maturity.