Comparative Effects of Soil-Applied Magnesium and Calcium Silicates On Drought Tolerance and Yield Performance in Peanut (Arachis hypogaea L.)
摘要
Drought stress is a major constraint to peanut productivity, particularly during reproductive development. This study evaluated the effects of two soil-applied silicate amendments, magnesium silicate and calcium silicate, on growth, physiological responses, nodulation, and yield formation in peanut (Arachis hypogaea) under drought stress. Peanut plants were grown under well-watered and drought-stressed conditions with or without soil-applied silicon at 50 mg L−1, supplied as magnesium silicate (179 mg L−1) or calcium silicate (207 mg L−1). Drought stress delayed flowering onset from 22.0 days after sowing under well-watered conditions to 33.0 days after sowing in untreated drought-stressed plants. It also reduced plant height from 27.57 to 20.56 cm, leaf area from 2.66 to 0.60, and individual plant yield from 10.76 g plant−1 to 4.13 g plant−1. Silicon application improved several drought-affected traits. Under drought stress, magnesium silicate increased plant height, leaf area, total pod number, and filled pod ratio by 21.4%, 96.7%, 65.7%, and 86.2%, respectively, compared with untreated drought-stressed plants. Calcium silicate also improved these traits, although the responses were generally lower than those obtained with magnesium silicate. Significantly, magnesium silicate increased individual yield from 4.13 to 6.54 g plant−1, representing an absolute increase of 2.41 g plant−1 (58.4%), while calcium silicate increased individual plant yield to 5.38 g plant−1, corresponding to an increase of 1.25 g plant−1 (30.3%) relative to untreated drought-stressed plants. Physiological measurements showed that magnesium silicate reduced water saturation deficit from 25.68% to 18.97%, electrolyte leakage from 74.99% to 56.44%, and proline accumulation from 450.06 to 223.61 µg g−1 fresh weight at the pod-filling stage. Plants treated with magnesium silicate or calcium silicate also maintained higher nodule number and nodule biomass under drought stress. Taken together, the results indicate that soil application of magnesium silicate and calcium silicate at an equivalent silicon rate can mitigate drought-induced damage in peanut. Magnesium silicate showed greater potential than calcium silicate for improving physiological stability, nodulation, and yield performance under water-deficit conditions.