Optimization of boron sources and levels for improving morpho-physiological traits, yield, and soil fertility under groundnut (Arachis hypogaea L.) in calcareous soil condition
摘要
Boron deficiency is a major nutritional constraint in calcareous soils due to high pH and elevated calcium carbonate content, which restricts boron availability. In the present study, a field experiment was conducted to evaluate the effect of different boron sources and levels on the growth, yield, nutrient uptake, and post-harvest soil fertility of groundnut (Arachis hypogaea L.) grown in calcareous soils. Treatments included two boron sources, borax (S1) and boric acid (S2), applied at four levels: 0, 2.5, 5.0, and 7.5 mg kg⁻¹ of soil. Boron application significantly improved plant height (51.35 cm), number of branches per plant (12.53), dry matter production (5268 kg ha⁻¹), pod yield (2193 kg ha⁻¹), kernel yield (1507 kg ha⁻¹), and haulm yield (2927 kg ha⁻¹). It also enhanced nutrient uptake in pod and haulm, with nitrogen (48.46 and 41.27 kg ha⁻¹), phosphorus (6.38 and 6.41 kg ha⁻¹), potassium (12.28 and 50.63 kg ha⁻¹), and boron (2.45 and 4.64 g ha⁻¹), respectively, at harvest. Among the treatments, 7.5 mg kg⁻¹ as boric acid (S2L3) recorded the highest performance, but it was statistically on par with 5 mg kg⁻¹ as boric acid (S2L2), indicating that the boron requirement was adequately met at 5 mg kg⁻¹. Post-harvest soil analysis showed lower available N (237.11 kg ha⁻¹), P (9.33 kg ha⁻¹), and K (137.26 kg ha⁻¹) in S2L3 due to higher plant uptake, while available boron (0.63 mg kg⁻¹) increased significantly with boron application, especially with boric acid. These findings suggest that boric acid at 5 mg B kg⁻¹ is an agronomically optimal boron source for groundnut cultivation in calcareous soils under the present experimental conditions of a single season and single location; further multi-season and multi-location studies are required to validate these findings.