Effect of Fruit Harvest Time on the Nutritional and Agronomic Quality of Oleaginous Citrullus lanatus Seeds

Oilseeds of Citrullus lanatus are highly prized in African societies for their nutritional and socio-economic importance. In an attempt to improve their yield, remaining very low mainly due to lack of good nutritive and germinative quality seeds, the effect of fruit harvest time was studied. After growing plants of ʺwlêwlêʺ cultivar on Nangui Abrogoua University experimental site, fruits were harvested at six different times [15, 20, 25, 30, 35 and 40 days after anthesis (DAA)] then fermented to produce seeds for germination test concerning agronomic aspect and biochemical analysis for nutritional quality. Agronomically, results showed that delaying harvest time (from 15 to 40 DAA) significantly (P < 0.001) improved fruit weight (from 512.20 to 760.50 g) and their seed content (from 71.75 to 230.70 seeds/fruit), as well as size (from 10.69 to 11.42 mm) and weight (from 5.16 to 6.37 g) of dry seeds what lead to their optimum viability (89.50%). Nutritionally, apart from ash which didn’t vary, C. lanatus seeds reached their highest levels of flavonoids (0.03 mg/100g) and tannins (0.022 mg/100g) at 15 DAA, followed by protein (30.66%), lipids (56.60%) and vitamin C (2.25 mg/100g DM) ones at 35 days while dehydrating to reach the lowest moisture content (5.51%). Hence, this variety seeds reach their nutritional maturity earlier, already at 35 DAA, while their optimal germination quality occurs later at 40 DAA.