Effects of plant density and main stem pruning on yield and its components of pumpkin (Cucurbita pepo con var. pepo var. styriaca)

To evaluate the effect of stem pruning and plant density on yield and yield components of pumpkin, a factorial experiment based on randomized complete blocks design with three replications was carried out at the Research Field of University of Zanjan in spring 2011. In this study, plant density in three levels including 8000, 12000, 16000 plant/ha and stem pruning in three levels including no stem pruning and stem pruning after 14 and 18 nodes formation were investigated. Results showed that stem pruning had significant (p ≤ 0.05) effects on all traits except number of seed per fruit. The highest fruit yield (142.2 ton/ha) and seed yield (3219 kg/ha) were obtained at pruning of stem after formation of 14 nods and the lowest fruit yield (112 ton/ha) and seed yield (2775 kg/ha) were obtained at no stem pruning treatment. Also, results showed that the plant density had significant effect (p ≤ 0.01) on fruit and seed yield. The highest fruit yield (157.4 ton/ha) and seed yield (3754 kg/ha) was obtained in 16000 plant/ha and the lowest fruit yield (93.5 ton/ha) and seed yield (2170.8 kg/ha) were obtained in 8000 plant/ha. Interaction effect of stem pruning and plant density on measured traits was not significant.