Effect of Planting Date on Growth, Carotene and Root Yield of three Sweetpotato Varieties [Ipomoea batatas (L.) Lam.] in South-East Nigeria
Abstract
There is paucity of information on the effect of time of planting on sweetpotato in South-East Nigeria and hence the need for this study; where four planting dates were assessed under field conditions for their comparative effects on growth, carotene, and root yield of orange-fleshed sweetpotato varieties at the National Root Crops Research Institute, Umudike, Nigeria in 2013 and 2014 cropping seasons. The experiment was a split-plot laid out in randomized complete block design with three replications. The main plot treatments were three sweetpotato varieties (Umuspo 1, Umuspo 3, and Ex-Igbariam), while the sub-plot treatments were four planting dates (April, May, June, and July). Results indicated that delayed planting from April to other planting dates significantly reduced orange-fleshed sweetpotato fresh shoot biomass and dry matter. Similarly, planting in April, 2013 produced significantly (p<0.05) higher storage root yield than planting later in May, June, and July by 75%, 92%, and 149%, respectively. In contrast, delayed planting up to June produced a carotene yield of 1267.7µg/g, which was higher than those of April and May by 180% and 82%, respectively. On average, Umuspo 1 produced significantly greater biomass of shoot and root. In 2013, Umuspo 1 also produced higher storage root yield than Umuspo 3 and Ex-Igbariam by 61% and 46%, respectively. However, Umuspo 3 produced significantly highest carotene yield (1918.0µg/g), followed by Umuspo 1 (582.0µg/g), while Ex-Igbariam had the lowest value (296.5µg/g). There were no significant interaction effects on root yield in both years, but there was a significant interaction on carotene yield, which was highest in Umuspo 3 in July, followed by the June planting date. For high fresh shoot and storage root yields, planting Umuspo 1 in April is recommended, while for high carotene yield, planting Umuspo 3 in June or July is recommended.
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