Effect of Cattle Manure and Sulfur on Yield and Oil Composition of Pumpkin (Cucurbita pepovar. Styriaca) Inoculated withThiobacillus thiooxidansin Calcareous Soil

The effect of cattle manure and sulfur fertilizer on seed yield and oil composition of pumpkin (Cucurbita pepo var. Styriaca) under inoculated with Thiobacillus thiooxidans was investigated in a factorial study based on a randomized complete block design. Experimental factors consisted of cattle manure (M) (M0: 0, M1: 10; and M2: 20 t ha−1), sulfur (S) (S0: 0, S1: 250; and S2: 500 kg ha−1) and T. thiooxidans (B): inoculated (B1) and non-inoculated (B0). Results demonstrated that the application of T. thiooxidans, cattle manure, and S fertilizer decreased the soil pH. The largest number of seed per fruit (367), highest fruit yield (70.57 t ha−1), seed iron (Fe) content (16.26 mg 100 g−1), and seed yield (111 kg ha−1) was obtained when 20 t ha−1 manure was applied in combination with 500 kg ha−1 S inoculated with T. thiooxidans. In this condition, the content of S, Fe, phosphorus (P), and nitrogen (N) in plant shoots was increased by 44.8%, 22.58%, 33.89%, and 10.38%, respectively, compared to the control. Moreover, the highest content of seed protein was observed in 10 t ha−1 manure and 500 kg ha−1 S fertilizer inoculated with T. thiooxidans. When 250 kg ha−1 S fertilizer was applied, 20 t ha−1 manure decreased seed P content sharply. At the rate of 500 kg ha−1 S fertilizer, the highest content of seed P was obtained from 20 t ha−1 manure. Totally, 20 t ha−1 cattle manure, along with 500 kg ha−1 S fertilizer as well as T. thiooxidans inoculation, improved oil and seed yield of medicinal pumpkin.