International Journal of Horticulture, 2016, Vol.6, No.22, 1-14
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fruits which are preferred qualities for farmers in terms of income. Fruit yield is a function of genes expression
and in response to the growing environmental conditions. Since all varieties in this study were grown under the
same environmental conditions, fruit yield depended on the genetic potential of a variety.
There were varied responses in growth component of the varieties to manure application for both rainy and late
season crops. There were varied responses in growth component of the varieties to manure application for both
rainy and late season crops. For rainy season crops, the result showed that the effect of NPK fertilizer was
significant over organomineral (OMF) and control on growth characters of watermelon. Agele and Olabomi (2010)
and Agele et al. (2011) observed similar increase in growth parameters of tomato and pepper in Akure, Nigeria on
application of NPK fertilizer and farm yard manure. The vigour of growth of Anderson in the unmanured control
was better while NPK fertilizer enhanced growth of Charleston Grey and Anderson in the rainy season Sabo et al.
(2013). Although, the growth components of Anderson improved when manured in rainy season but this was
accompanied by lower fruit yield. This result supports the claim of Silva et al. (2007), Dauda et al. (2008) and
Audi et al. (2013) that inorganic fertilizer promoted vegetative growth in watermelon but caused reduction in
number of fruits, delayed and reduced fruit setting. The effect of NPK and OMF application was profound on
number of fruit rots, cracked fruits and fruit diameter. NPK gave larger fruit compared to control but recorded
higher number of fruit disorders in both seasons. High fruit rot due to NPK may be due to excessive vegetative
growth due to NPK fertilizer application. In Capsicum spp, excessive growth aggravates blossom-end -rot
disorder because the huge demand for N may shut Calcium away from the fruit. Calcium is not translocated
within the plant from older to younger tissues; therefore young fruits are especially sensitive to a lack of calcium
(Bar Tal et al., 2001; Agele & Olabomi, 2010). However, in other to produce bigger fruits, NPK fertilizer is
required for watermelon. Ogunremi (1990) reported increase in the yield of melon fruits due to fertilizer
application. The effect of OMF and NPK fertilizers was not significant on most yield characters measured. OMF
application enhanced number of fruit rot over the control. This may still be due to presence N in OMF. The control
produced significantly higher fruit weight over the NPK and OMF. The higher fruit weight in the control was
accompanied with higher moisture content of the watermelon fruit. In the rainy season crop, application of NPK
and organo-mineral fertilizer enhanced performance of watermelon varieties in terms of fruit yield components.
Highest number of fruits, fruit length, and fruit diameter and fruit weight were produced in Crimson sweet when
treated with NPK and the same was recorded in Anderson, and Sugarbaby under combination of organo-mineral
fertilizer. Organo-mineral fertilizer appears advantageous for low input system for improving nutrient status of
tropical soils: Adeoye et al. (2008) and Agele et al. (2008).
However, among the varieties, Sugarbaby showed no record of fruit rot for all fertilizer types tested despite the
high number of fruits produced. This implies that Sugarbaby performed best in both seasons and there is
possibility of producing larger and heavier fruits when treated with mineral fertilizers. Charleston Grey has been
noted for its fewer but larger and heavier fruits but highest number of fruit rots when manured or unmanured in
the rainy season. This implies that this variety is not adequately adapted to rainy season environmental conditions.
The number of fruits produced by Anderson in unmanured plot was still reasonably high and Crimson sweet will
perform well when manured in the rainy season. The late season enhanced response of Charleston grey as it
produces highest number and highest fruit weight and no fruit rot when manured or not. Hence this variety may
thrive well and is better adapted to the late season. This shows that Anderson when manured can perform well as
both rainy and late season crop. Sugarbaby which was observed as the best variety in the rainy season (no record
of fruit rot) across manure types did not follow this same trend as late season crop, when it had large number of
