Effect of Organic, Biological and Chemical Fertilizers on Yield, Yield Components and Oil Percent of Common Purslane (Portulaca oleracea L.)

Introduction: Purslane (Portulaca oleracea L.) is an annual and C4 plant that belongs to the family of Portulacaceae that is tolerant to drought and salt stresses which contains high amounts of beneficial omega-3 fatty acids and antioxidant vitamins. Adaptation to both dry and saline conditions makes Purslane a prime candidate as a vegetable in areas with dry conditions and salty soils, often present together where land is irrigated. Purslane seeds provide nutritional value and have beneficial health effects on the body, especially in preventing cardiovascular, cancer, and hypertension (high blood pressure) diseases, because it contains omega-3 and omega-6 fatty acids and other nutrients like antioxidants, tocopherols, and dietary fiber. Nitrogen is a key element in soil fertility and crop production. Recently, attention to the soil quality and health has increased, especially for sustainable production of medicinal crops. Thus, using natural and on-farm inputs has been considered, to produce healthy food especially in developed countries. Achieve this goal needs organic fertilizers. Given the importance of Purslane as a medicinal plant and the fact that there is no detailed information about the nitrogen requirement for this plant, this study was conducted to evaluate the effect of organic, biological and chemical fertilizers on yield, yield components and percent oil of common Purslane (Portulaca oleracea L.) in Birjand, Iran. Materials and Methods: This research was carried out during two growing seasons (2014/2015 and 2015/2016) at the research farm of Birjand University. In this experiment, the treatments were a combination of four sources of nitrogen supply, including cow manure, vermicompost, chemical fertilizer (NPK) and control (without any fertilizer), as well as four types of biofertilizers including nitroxin (including Azotobacter and Azospirilum), Mycorrhiza (Glomus intraradices), Biosulfur (including Thiobacillus with sulfur) and control (without any fertilizer) on Purslane in a factorial design based on randomized complete blocks design with three replications. The studied characteristics were performed separately in each harvest. From each plot, ten plants were randomly selected, and plant height and SPAD index were measured. Five plants were randomly selected from each plot, and yield components, including the number of capsules per plant, number of seeds per capsule, 1000-seed weight, biological yield, and harvest index, were calculated. The grain yield was performed when yellowing of 70% of the capsules. The oil percentage was measured by Soxhlet method. Oil yield was calculated by multiplying grain yield by oil percentage. Statistical analysis was performed using Minitab 17 software. LSD test was used at the 5% probability level to compare the means. Results and Discussion: The results showed that the effect of organic and chemical fertilizers on all studied traits (except harvest index) was significant. The highest plant height (49.24 cm), number of capsules per plant (351.23 capsules) and 1000- seed weight (0.41 g) was related to NPK treatment. The highest chlorophyll index (34.27), seed number per capsule (45.4) and seed oil percentage (14.6) was related to vermicompost treatment. Also, the highest grain yield (1959.29 kg.ha-1), biomass yield (9782.43 kg.ha-1) and oil yield (277.68 kg.ha-1) were obtained from NPK treatment, while no significant differences were observed between NPK fertilizer and cow manure. The effect of biofertilizer on number of capsules per plant, number of seeds per capsule, 1000-grain weight and oil content was significant, but the effect on the other traits was not significant. The highest number of capsules per plant (355.38 capsules) and 1000 seed weight (0.41 g) was related to mycorrhiza treatment, but the highest number of seeds per capsule (43) and oil percentage (14.6) were related to biosulfur treatment. The interaction of two studied factors (different nitrogen sources and biofertilizers) on plant height, chlorophyll index, capsule number per plant, biomass yield, harvest index and oil percentage were significant. The maximum biomass yield was obtained of the interaction between NPK and Nitroxin (10670.1 kg.ha-1), and the interaction between NPK and biosolfur (10306.7 kg.ha-1). The maximum percentage of oil was obtained of control and biosolfur treatments (15.4%). Conclusions Based on the results of this study, it is recommended to replace cow manure with NPK fertilizer to minimize the application of chemical inputs and maximize production of purslane seed and oil in Birjand.