Effect of pruning on growth, development, seed yield and active substances of Pumpkin (Cucurbita pepo convar. pepo var. styriaca)

The objective of this study was to investigate the effect of pruning in different developmental stages on growth, development, seed yield and active substances of medicinal pumpkin (these active substances are uses for remedy the Benign Prostatic Hyperplasia (BPH)). The experiment was performed in a RCB design. Five pruning treatments in different developmental stages (no pruning, after 3-5 nodes, after 6-8 nodes, after emergence of first flower, after emergence of 8th to 10th flowers) were applied. After performing soil analysis of experimental site, we made 3 furrows, 2 m apart from each other, then the seeds were sown on 50 cm spaces on the rows (4 seeds in each hole), in April 26th, 2003. After the vines reached the mentioned stages, pruning treatments were applied by cutting the main stem. When the fruit matured (became yellow), were harvested and carried to the laboratory, the fresh weight of fruits was measured, then the seeds were cut out, counted and their fresh weight was measured. The seeds were air dried and their dry weight was calculated. The oil was extracted from dried seeds by maceration method and the extract constituents were quantified by means of GC. Pruning in 6-8 nodes stage resulted in higher fruit number, total fruit fresh weight, total seeds dry weight and number of seeds, comparing with other treatments. Control treatment, resulted in a higher weight of 1000 seeds. However, seed fresh weight and seed oil content, was not affected by pruning and did not show any significant difference between treatments. Furthermore applying pruning treatment in 6-8 nodes stage showed a considerable increase in the content of fatty acids including: palmitic, stearic, oleic, and linolenic. Although pruning resulted in reducing fruit size, it affected the quality and quantity of final product and increased the active substances.