Fruit and seed physiological quality changes during seed development and maturation in African eggplant (Solanum aethiopicum L.)

Abstract

This work aimed at determining the optimum harvest time of African eggplant (Solanum aethiopicum L.) seeds, cv. Oforiwa and cv. Kpando for maximum physiological seed quality under tropical (TCC) and temperate oceanic climatic (TOC) conditions. Fruit morphological metrics such as fruit weight and size were also related to seed physiological quality. Seeds were harvested at different maturation stages from 20 to 82 days after anthesis (DAA). Seed quality was assessed according to moisture content, dry seed weight, seed length, thousand seed weight, percentage germination and emergence. The results indicated that seeds harvested precociously (20 and 34 days after anthesis), did not germinate or recorded very low percentage germination (0-20%). Considering all the fruit morphological traits and seed quality variables measured, the results indicate that maximum seed quality (that is, germination, emergence, seed weight and mean germination time) are obtained from fruits harvested at 76 DAA. The physiological maturity (PM) (maximum seed dry weight) for cv. Oforiwa was attained at 62 DAA while cv. Kpando took 14 days more to reach physiological maturity but coincided with maximum germination at 76 DAA. The results further showed that fruit characteristics such as weight and size are associated with seed physiological quality in African eggplant. It is thus recommended that fruits of African eggplant cv. Oforiwa and cv. Kpando should be harvested at 70 to 76 DAA for maximum seed germination and emergence.

Influence of Seed Development and Maturation on the Physiological and Biochemical Seed Quality

“…Several studies on seed development and maturation have revealed that seeds of some species attain germination potential very early just few days after anthesis but some requires sometime in order to attain the ability to germinate. This variation exists even within the same species as observed in two species of S. aethiopicum, Oforiwa and Kpando [36]. However, as discussed previously, it is also possible to harvest seeds one or two weeks before physiological maturity and give them a period of after ripening to attain full maturity and hence good germination and vigor, particularly for those borne in fleshy fruits [54].…”

“…However, this seems to be affected by genotype as [60,61] obtained contrasting results in antioxidant enzyme activity trends in the same crop. High antioxidant enzyme activity during early seed development has been reported in African eggplant [62] and Hevea brasiliensis L [63]. Both authors reported a decline after an early increase, and increase at the end of the seed maturation phase.…”

“…Physiological maturity, often defined as a maturity stage at which the seed accumulates maximum dry matter, sometimes coincides with maximum seed germination, example in Solanum aethiopicum [31] and Okra [32] but in the case of species such as tomato [33], soybean [34] and pepper [35], this scenario is not applicable. Botey et al [36] studied seed development of two African eggplant cultivars; Oforiwa and Kpando at different seed development stages of 20, 34, 48, 62, 76 and 82 days after anthesis (DAA) and reported that maximum seed dry weight was attained at 48 and 76 DAA in Oforiwa and Kpando respectively under a characteristic tropical climate, and 62 and 76 DAA respectively under a characteristic temperate oceanic climate, but maximum germination percentage only coincided with physiological maturity in cultivar Kpando. Another study in six eggplant cultivars; Dwomo and Kpando belonging to Solanum gilo group, GH 3870 and GH 3887 belonging to Solanum melongena group, GH 107 and GH 4918 belonging to Solanum macrocarpon group showed that seed germination and vigor improved when seed were harvested from 4 weeks to 8 weeks after full maturity of the fruits [31].…”

“…This phenomenon has been demonstrated, for example maximum germination and vigor in tomato seeds were attained 15 days after PM [48] while [49] reported 20 days after PM in the same crop, and [50] reported 10 days after PM in pepper. Changes in fruit color, fruit weight, fruit diameter and length, seed dry weight and seed moisture content during seed development can be used as indicators for seed maturation and harvesting to attain good seed quality [36,42,44]. Seed vigor during seed development can be measured indirectly using electrical conductivity, with lower EC values indicating high seed vigor and vice versa.…”

Relación del estado de maduración del fruto y el almacenamiento postcosecha en la calidad fisiológica de semillas de chile dulce criollo (Capsicum annuum L.)

“…Las semillas obtenidas de frutos maduros tienen capacidad de germinar, sin embargo, tienen menor velocidad de germinación (Figura 6) y la emergencia tiende a ser menor que la semilla cosechada de frutos menos maduros (Figura 8), es probable que las semillas obtenidas de los frutos maduros hayan comenzado a presentar deterioro, pues la madurez fisiológica de la semilla pudo haber sido alcanzada en los estados de maduración anteriores (Botey et al, 2021). Este comportamiento resultó diferente a los resultados de Cavero et al (1995), quienes encontraron mejores resultados en la germinación de las semillas extraídas de frutos completamente maduros a los que se les permitió madurar en exceso.…”