Understanding the interactions and relationships between fertilizer and minerals help to have optimum fertilization ­practice with the lowest costs. In a split plot field experiment, we studied the effect of some organic substrate (control (soil), spent mushroom compost (SMC), cow manure and vermicompost) and different levels of phosphorus (at 0, 75, 100 and 125 kg h–1) to investigate the best treatment for some characters of medicinal pumpkin (Cucurbita pepo L.) such as: leaf and branch number, plant height, fruit number, fruit weight, seed number, oil percentage, zinc and phosphorus content of seeds. Results showed that vermicompost is the best organic substrate for improving of the most characters. For phosphorus application alone, 100 (kg.h–1) was the best treatments for most characters and in combined application of organic substrate and phosphorus, vermicompost with 100 (kg.ha–1) was the best treatment to increase the morphological and yield factors.

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