Optimizing Climate Smart Soil Amendments Using Peat Moss, Biochar, and Ascorbic Acid to Improve Maize Yield under Drought

Climate change has severely affected agricultural water availability. In this two-year pot experiment, maize (Zea mays L. cv. Pioneer 4040) was grown at 85% (I-1), 65% (I-2), or 45% (I-3; severe drought) of field capacity. Eight treatments were applied at each water-stress level: peat moss (T1), foliar ascorbic acid (T2), biochar (T3), peat moss + ascorbic acid (T4), peat moss + biochar (T5), ascorbic acid + biochar (T6), all three amendments (T7), and an untreated control (T8). Peat moss and biochar were each applied at 15% of soil weight, and ascorbic acid was applied at 40 mg/L. Each treatment × water-stress combination had three replicate pots per season. Measurements included chlorophyll fluorescence, photosynthetic pigments, catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), proline, soluble sugars, sucrose, leaf water content, plant height, ear length, ear diameter, grain weight per ear, and 100-grain weight. Data from each season were analyzed separately by two-way factorial analysis of variance (ANOVA) under a completely randomized design (CRD), with the pot as the experimental unit (n = 3). Treatment and water-stress effects were significant for the measured crop parameters in both seasons (p ≤ 0.05). Increasing water stress reduced chlorophyll fluorescence, chlorophyll content, and yield parameters. Combined treatments generally performed better than single treatments at all water-stress levels, including severe drought, with T7 generally producing the best results. Although CAT, SOD, and APX activities and soluble sugar and sucrose contents increased with water stress, proline content and yield parameters decreased. These pot-scale findings support further evaluation of combined amendments for improving maize performance under water deficit.