Yield and water use efficiency in buttercup squash (Cucurbita maxima Duchesne) and heritage pumpkin (Cucurbita pepo Linn)

There is scarce information on agronomic performance, which would support a resurgence of interest in the heritage pumpkin, Kamokamo, relative to exported Buttercup squash in New Zealand. Furthermore, pumpkin squash fruit yield and fruit sizes fluctuate with seasonal climate variability. A split-plot design field experiment was conducted, in order to compare their yield, water use efficiency and fruit size distribution under irrigation and rain-fed conditions. Rain-fed and irrigation were the main plots: replicated four times. The cultivars were subplots, planted at 2.2 plants m(-2) that received 700 kg ha(-1) Nitrophoska Blue TE at planting, followed by 66 kgN ha(-1) of Urea. Pumpkin fruit yield and yield components, water use efficiency and total biomass data was subjected to ANOVA, by using the PROC GLM procedure in SAS. Soil moisture content (%) was affected by cultivar (p < 0.0001) and irrigation (p < 0.0001). Fruit yield, total biomass and water use efficiency differed significantly amongst cultivars (p < 0.0001). Kamokamo shows the highest fruit yield, total biomass and water use efficiency. Irrigation had no effect on its fruit yields (p > 0.05) but it did affect its fruit size distribution (p < 0.05) and water use efficiency (p < 0.01). The results indicate that irrigation can modify standard marketable fruit sizes and that Kamokamo has a high yield and water use efficiency potential, compared to Buttercup squash.