نوع مقاله : مقاله پژوهشی
نویسندگان
1 بخش تحقیقات خاک و آب، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی فارس، سازمان تحقیقات، آموزش و ترویج کشاورزی، شیراز، ایران.
2 مؤسسه تحقیقات خاک و آب کشور، سازمان تحقیقات، آموزش و ترویج کشاورزی، کرج، ایران.
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objectives: Beans are highly effective in fixing nitrogen and enhancing the fertility of agricultural soils due to their symbiosis with bacteria, contributing large amounts of nitrogen to the soil annually after harvest. Pinto bean (Phaseolus vulgaris L.) is one of the major pulse crops grown in Iran. It is widely cultivated in dry and semi-arid regions. Cold stress is a major challenge for global agriculture, especially in cold regions. In these areas, the sowing date is delayed due to low temperatures or high moisture in the soil. Consequently, the seed yield of pinto beans significantly decreases with delayed sowing. Previous studies suggest that the application of chemical fertilizers (particularly zinc and phosphorus) and bio-fertilizers can induce early maturity under such conditions. Biofertilizers are important for improving the qualitative and biochemical properties of plants by enhancing soil quality, which is directly related to producing high-quality and functional food. Their use is particularly valuable in the cultivation of common beans. Phosphorous and zinc are the major potential yield-limiting nutrients in Iran. The deficiency of these nutrients becomes even more serious in alkaline calcareous dry soils. Another important aspect of P and Zn nutrition is the interaction effect between them, especially in soils marginally deficient in both elements. When P and Zn are applied together to such soils, crop yields are reported to increase due to the positive interaction of P and Zn. Therefore, considering the importance of the above, this study was conducted to assess the effect of the combined application of different rates of P, Zn, and bio-fertilizers on the yield and yield components of dry bean plants grown in a soil deficient in P and Zn in the north of Fars province, Iran.
Materials and Methods: A factorial experiment was conducted based on a randomized complete block design (RCBD) with three replications over two growing seasons (2022 and 2023) to evaluate the effects of biofertilizer application and different phosphorus and zinc fertilizer levels on the seed yield and growth indices of pinto beans. The experimental factors were: (1) phosphorus at three levels: the recommended rate based on soil test results (P1), 30% above the recommended rate (P2), and 30% below the recommended rate (P3); (2) zinc at three levels: the recommended rate based on soil test results (Zn1), 30% above the recommended rate (Zn2), and 30% below the recommended rate (Zn3); and (3) biofertilizer at two levels: seed inoculation with an inoculant containing Rhizobium, Azotobacter, and arbuscular mycorrhizal fungi (AMF) (B1), and no seed inoculation (B0). The measured traits included seed yield, root colonization, growing degree days (GDD), crop growth rate (CGR), 100-seed weight, seed nutrient contents (N, P, K, and Zn), seed protein content, plant height, and number of pods per plant.
Results: The results of the analysis for some selected physical and chemical properties of the soil used are given in Table 1. The soil has a silty clay texture, an alkaline pH, and is calcareous with a calcium carbonate content of 25%. The soil is non-saline with a low organic matter content (<5%) and is deficient in total N content, which is typical for semi-arid soils. ANOVA revealed significant (P < 0.01) effects of phosphorus, zinc, and bio-fertilizers on yield, CGR, biomass (dry and fresh weight), and pod and seed counts per plant. The highest yield (2170 kg ha⁻¹) was recorded in the P1Zn2B0 treatment (30% more P, 30% less Zn, and no inoculation). GDD averaged 1056 and 1088 in the first and second years, respectively. The maximum CGR (5.5 g m⁻² day⁻¹) occurred in inoculated seeds under the P2Zn3B0 treatment. The highest pod (14.3) and seed counts per plant (48) were observed in the P3Zn3B0 treatment, while seeds per pod peaked at 1.4 in the P3Zn2B0 treatment. The maximum plant height (94 cm) was observed in the P2Zn1B1 and P2Zn3B1 treatments. Seed phosphorus was elevated by bio-fertilizer inoculation, and root colonization peaked at 72.7% in the P1Zn3B0 treatment. The highest 100-seed weights were 46.2 and 50.7 g in the two years of the experiment. The 100-seed weight was increased by zinc and bio-fertilizer treatments, whereas phosphorus did not affect the 100-seed weight. Economic analysis favored the P3Zn3B0 treatment with the highest gross return (1255.8 Rials).
Conclusion: Bean responses to P, Zn, and biofertilizers were strongly dependent on environmental conditions and nutrient interactions, with variations in grain yield primarily associated with the seed number per plant. The inconsistent effects of biofertilizers and year-dependent treatment responses highlight the need for balanced, site-specific nutrient management rather than fixed fertilizer rates. Seed nutritional quality was largely stable, while root colonization suggested a potential contribution from indigenous mycorrhizal populations. Overall, optimizing the P–Zn balance according to soil and environmental conditions appears more promising than increasing fertilizer inputs, although multi-year validation is required.
کلیدواژه‌ها [English]
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