دوماهنامه
نوع مقاله : مقالات پژوهشی
نویسندگان
1 مؤسسه تحقیقات خاک و آب، سازمان تحقیقات، آموزش و ترویج کشاورزی، کرج، ایران
2 مرکز تحقیقات کشاورزی و منابع طبیعی استان فارس، سازمان تحقیقات، آموزش و ترویج کشاورزی، داراب، ایران
کلیدواژهها
عنوان مقاله English
نویسندگان English
Introduction
Phosphorus (P) is an essential nutrient for plant growth. In calcareous soils, the presence of calcium carbonate affects the availability of phosphorus to plants. Due to the special behavior of phosphorus and its low availability in calcareous soils of Iran, the need to identify crop varieties that are efficient in absorbing and utilizing this nutrient is vital. On the other hand, following the global fertilizer crisis and the sharp increase in input prices, focusing on efficient fertilization strategies has become an important priority. Among oilseed plants, sesame (Sesamum indicum) ranks fifth in the world and second in Iran in terms of oil production. Despite its economic importance, sesame has received less attention in phosphorus nutrition management studies. Therefore, this research was designed and implemented with the aim of providing a practical solution to improve yield per unit of phosphorus consumed, as a necessary step towards increasing farmers' profitability and strengthening the country's food security.
Materials and Methods
This study was conducted as a factorial experiment in a randomized complete block design at Darab Agricultural Research Station, Fars Province, for two years during the 2019 and 2020 growing seasons. Soil available phosphorus was below the optimal range and the irrigation system used was drip irrigation. The soil texture was relatively heavy, the percentage of soil organic carbon was low, and the equivalent calcium carbonate was high. The soil was non-saline and the amount of available phosphorus and zinc was insufficient. The irrigation water was non-saline. The treatments studied included five phosphorus levels (0, 5, 10, 15, and 20 kg ha-1 of phosphorus from a triple superphosphate source with 20% phosphorus) and two sesame cultivars, Darab 14 and Darab 1. The phosphorus levels, along with 50% of nitrogen fertilizer, 50 kg ha-1 potassium sulfate and 30 kg ha-1 of zinc sulfate were applied before planting. The remaining required nitrogen fertilizer (50 kg ha-1 of urea) was applied before flowering. At the harvest stage, yield and yield components, phosphorus and micronutrients concentrations in the grain were measured. Nutrient uptake in the grain, seed oil percentage, and phosphorus efficiency indices of the grain were also determined.
Results and Discussion
Based on the two-year average results, the grain and oil yield of the Darab 14 cultivar were 20.4% and 30.6% higher than those of the Darab 1 cultivar, respectively. The number of capsules per plant, the number of seeds per capsule, grain yield, and oil yield increased significantly up to the application level of 10 kg of phosphorus per hectare (by 23.5%, 20.4%, 42.7%, and 52.9%, respectively), although they showed no significant difference compared with the 5 kg P ha⁻¹ treatment. Therefore, for these cultivars, the application of 5 kg P ha⁻¹ is recommended in terms of grain and oil yield. Measurement of seed phosphorus concentration at different phosphorus levels indicated that a range of 0.25% to 0.28% can be considered as the seed phosphorus sufficiency threshold for these cultivars. Over the two-year average, the uptake of phosphorus, nitrogen, iron, manganese, and zinc was higher in Darab 14 than in Darab 1. The maximum uptake of nitrogen was recorded at 10 kg P ha-1 (49.3 kg ha-1), which was significantly different from the control treatment (36.3 kg ha-1). However, with further increase in phosphorus application, the amount of nitrogen uptake decreased. The maximum uptake of iron occurred at 10 kg P ha-1, but was not significantly different from the level of 5 kg P ha-1. For the elements manganese, zinc, and copper, the maximum uptake was also recorded at 10 kg phosphorus/ha. Further increase in phosphorus application rate decreased the uptake of these elements. The uptake of zinc at 20 kg P ha-1 decreased by about 4.9% compared to the control treatment. At all phosphorus application levels, Darab 14 outperformed Darab 1 in terms of grain yield, phosphorus uptake, and phosphorus use efficiency. Darab 14 produced a higher yield per unit of phosphorus applied compared to Darab 1. Sesame seed yield was positively and significantly correlated with seed phosphorus uptake (0.82**). Sesame is known for its strong root system and low nutrient requirements, but the present study showed that sesame's ability to uptake phosphorus is limited at this level of available phosphorus (8.2 mg kg-1). Seed yield was significantly correlated with nitrogen uptake (0.82**), iron uptake (0.59**), manganese uptake (0.86**), zinc uptake (0.75**), and copper uptake (0.73**).
Conclusion
By cultivating phosphorus-deficiency tolerant cultivars such as Darab 14, along with minimal phosphorus fertilizer application (5 kg ha⁻¹ under the present experimental conditions), farmers can not only achieve optimal yield but also significantly enhance profitability and increase resource use efficiency in calcareous soils with phosphorus deficiency.
For farmers, grain yield is more important than oil yield because sesame seeds are purchased based on seed weight rather than oil content. This results in a more favorable profit-to-cost ratio based on the harvested seed weight.
Acknowledgements
This project was part of the National Project of the Soil and Water Research Institute. The cooperation of this institute, as well as the cooperation of the Darab Agricultural Research Station of Fars Province, and the General Directorate of Cotton and Oilseeds of the Ministry of Agricultural Jihad for providing project fundingis gratefully acknowledged.
کلیدواژهها English
Authors retain the copyright. This is an open access article distributed under Creative Commons Attribution 4.0 International License (CC BY 4.0)
