Evaluation of Biomass Yield and Nitrogen and Phosphorus Efficiency Indicators of Portulaca (Portulaca oleracea L.) Affected by Organic, Chemical and Biological Fertilizers

Purslane (Portulaca oleracea L.) is an annual and C4 plant belonging to the family portulacaceae. The plant is drought- and salt-tolerant which contains high amounts of beneficial omega-3 fatty acids and antioxidant vitamins. Nitrogen is the key element in soil fertility and crop production. Attention to the soil quality and health has increased in recent years, especially for sustainable production of medicinal crops. So that, for production of healthy food in industrialized countries, using natural and on-farm inputs has been considered. One of the practical ways to achieve this goal is organic and biofertilizers. Given the importance of purslane as a medicinal plant and due to the fact that there is not detailed information about the nitrogen requirement for this plant, this study was conducted to evaluate the effect of organic, biological and chemical fertilizers on biomass yield, N and P use efficiency of the purslane in Birjand, Iran.

This research was carried out during two growing seasons from 2014 to 2016 at the research farm of Birjand University. The experiment was conducted as factorial based on a randomized complete block design with three replications. The treatments were a combination of four sources of nitrogen supply, including cow manure, vermicompost, fertilizer (NPK) and control (without any fertilizer), as well as four types of biofertilizers including nitroxin (Azotobacter and Azospirilum), Mycorrhiza (Glomus intraradices), Biosulfur (Thiobacillus with sulfur) and control (without any fertilizer). The studied traits included stem biomass yield, nitrogen and phosphorus percentage, nitrogen and phosphorus content, nitrogen and phosphorus uptake efficiency, nitrogen and phosphorus physiological efficiency and nitrogen and phosphorus agronomic efficiency based on biomass. Statistical analysis was performed using Minitab 17 software. To compare the averages, LSD test was used at the 5% probability level.

The results of the experiment showed that in chemical fertilizer (NPK) treatment, nitroxin consumption increased biomass yield (45.6%), nitrogen agronomic efficiency of biomass (52%), biomass phosphorus (2 times), the content of biomass phosphorus (2.8 times). On the other hand, biosulfur consumption increased biomass nitrogen (52.9%), biomass nitrogen content (2 times) and nitrogen uptake efficiency (2.1 times) compared to the control treatment. In the treatment of cow manure, the use of nitroxin increased the physiological efficiency of biomass (8%), however in the control treatment, the use of nitroxin increased the efficiency of phosphorus uptake (22.4%). Also in control treatment, the use of mycorrhiza and biosulfur (29.9% and 21.4%, respectively) increased the physiological efficiency of biomass phosphorus compared to the control treatment. On the other hand, consumption of nitrogen fertilizer sources reduced phosphorus agronomic efficiency of biomass compared to the control.

Based on the results of this experiment, in Birjand region, the use of chemical fertilizer (NPK) and nitroxin are recommended to achieve maximum biomass yield and phosphorus and nitrogen use efficiency.