Medicinal pumpkin (Cucurbita pepo convar. pepo var. styriaca) is an important annual plant that belongs to Cucurbitaceae family. The seeds of this plant, which are used to cure the prostatic hypertrophy and urinary tract irritation, contain fatty oil, β-sitosterol and E-vitamin as active substances and Zn as important nutritional element The effect of nitrogen levels on leaf N and chlorophyll (a, b, and total) content, seed yield, oil yield, and Zn content was examined. The nitrogen treatments were at five levels (0, 75, 150, 225, and 300 Kgha-1) that were applied at three different stages of the plant growth (seed sowing time, four leaf stage and flowering). The results indicated that nitrogen fertilization increased the amount of chlorophylls and N content of the leaves compared to the control. The highest rate of chlorophylls and N content of the leaves was obtained when nitrogen applied at 300 and 225 kgha-1 level, respectively. Also the highest seed dry weight and oil seed content were obtained at 75 kgha-1 of nitrogen. The highest β-sitosterol level showed at 150 kgha-1 of nitrogen. Zn content of the seeds decreased with nitrogen increasing, but the control indicated highest amount of the Zn.

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