Effect of methanol foliar application and planting date on fruit yield, oil content and composition of pumpkin (Cucurbita pepo convar. pepo var. styriaca)

fatty acid composition of pumpkin (Cucurbita pepo convar. pepo var. styriaca), a split plot experiment was conducted in a randomized complete block design with three replications during 2013-2014. Three planting dates (21 April, 22 May, 22 June) as the main factor and application of methanol (30% V/V) in four levels (control, pre-production phase, post-production phase, seed filling stage) were studied as the sub factor. Results showed that the interaction effect of planting date and application of methanol on seed yield in fruit, seed dry weight, 1000-seed weight, fruit yield, oil percentage and fatty acids compositions were significant at 1% probability level. The highest seed yield, seed dry weight, fruit yield, and oil content were obtained in the methanol foliar application in the pre-production phase in June 22. The highest 1000-seed weight (1155.6 g) was belonged to the methanol foliar application in the post-production phase in June 22. The foliar application treatments in seed filling stage in June 22 and control treatment also in May 22 showed the highest amount of oleic acid. The highest amount of linoleic (43.36%), linolenic (1.86%), and palmitic (21.20%) acids was obtained under methanol foliar application in the post-production phase in May 22, June 22 and April 21, respectively. The control treatment showed the highest amount of stearic acid (11.5٪) in the first planting date (April 21). Finally, the planting date of medicinal pumpkin in June 22 with foliar application of methanol in the pre-production phase in order to increasing of yield, and foliar application in the post-production phase to improve the qualitative traits of oil are recommended.