Response of Three Cucumber Varieties (Cucumis sativus L.) to Planting Season and NPK Fertilizer Rates in Lowland Humid Tropics: Sex Expression, Yield and Inter-Relationships between Yield and Associated Traits

摘要

The response of three cucumber varieties (Ashley, Betalpha, and marketmore ) to different rates of fertilizer (NPK 15:15:15) application were evaluated in two seasons (early and late) under rain-fed conditions in 2011 cropping season. The experiment was laid out in a split-split-plot in randomized complete block design with three replications. Seasons, (early and late rains) constituted the main plots, while cucumber varieties were fitted into the sub-plots with NPK fertilizer rates into sub-sub-plots. The results revealed significant increase in fruit yield of cucumber during the early planting season under rain-fed conditions in the humid tropics. During both cropping seasons, the application of N:P:K 15:15:15 fertilizer increased fruit yield of cucumber significantly up to 120 kg/ha. However, further increase did not affect fruit yield, which implies that 120 kg/ha fertilizer rate is the optimum quantity required for increased cucumber fruit yield. The interaction between cucumber variety and planting season significantly induced higher fruit yield in market-more compared to the other varieties tested. Principal component analysis showed that PC1, PC2 and PC3 with eigen-vector value loads greater than unity accounted for the cumulative variance of 70%, which exhibited the degree of influence the plant characters had on fruit yield. Pearson correlation indicated a highly significant (P<0.01) and positive correlation between fruit yield and weight of fruit (0.574**) as well as number of fruits per plant (0.574**). Cause and effect analysis revealed that maximum direct effect on fruit yield of cucumber was achieved through fruit weight (0.565) and number of fruits per plant (0.457). This implies that in selection for high yields, premium should be placed on these characters.