Foliar humic acid and salicylic acid application stimulates physiological responses and antioxidant systems to improve maize yield under water limitations

Abstract

Background Humic acid (HA) is an organic acid that is naturally present in soil organic matter and improves nutrient availability and the mechanisms involved in plant growth and development. Likewise, salicylic acid (SA) is an important plant hormone involved in the regulation of plant growth and development. A pot experiment was carried out to determine the effects of individual or combined HA and SA application on growth and yield of maize (Zea mays L.) under drought stress conditions. Two maize hybrids, namely, 30T60 (drought tolerant) and 75S75 (drought sensitive), were grown in semi‐controlled conditions and foliar applied with SA (1 mM), HA (100 mg L−1) and their combination (HA + SA). The plants were exposed to drought stress at the tasseling stage (R1, 60 days after sowing) for 2 weeks, while control plants were given normal irrigation. Results The results showed that HA and SA applications significantly enhanced the gas exchange characteristics (photosynthetic rate, transpiration rate, and stomatal conductance), and antioxidant activity (catalase, guaiacol peroxidase, and superoxide dismutase) of water stressed maize plants. Foliar SA spray significantly increased the photosynthetic efficiency and activity of enzymatic antioxidants closely followed by HA + SA application that ultimately improved the yield and net benefit cost ratio of maize under water deficit conditions. Conclusion Our findings suggest that foliar spraying of SA at the initiation of the reproductive stage is a cost‐effective strategy to obtain a high maize yield under limited water conditions.

Mitigation of drought stress in maize and sorghum by humic acid: differential growth and physiological responses

“…These findings coincide with the reported capability of HA to boost plant enzymatic and non-enzymatic defense systems for abiotic stress mitigation [110]. A similar HA-induced antioxidant system has been described in millet [26], sugarcane [96], rapeseed [100], and greenhouse-grown and HA-foliar sprayed maize at reproductive stage [111]. Such HA-promotive effects are attributed to its-induced upregulation of antioxidant enzymes-encoding genes such as CAT 1 and APX [112].…”

Performance Evaluation of New Table Grape Varieties under High Light Intensity Conditions Based on the Photosynthetic and Chlorophyll Fluorescence Characteristics

“…These leaves had good leaf color, similar size dimensions, and were free from diseases and insect pests [21]. The CIRAS-3 PP Systems photosynthetic analyzer (Amesbury, MA, USA) was used to measure the light response indices of the leaves [22,23]. A PLC3 universal leaf cuvette light source leaf chamber was utilized, and 10 gradients ranging from 0 to 2500 µmol•m −2 •s −1 (2500, 2000, 1500, 1000, 750, 500, 300, 150, 75, 0 µmol•m −2 •s −1 ) were set by the light source.…”

Response of Sugar Beet Growth to Soil Application of Humic Acid and Foliar Application of Some Biostimulators under Saline Soil Conditions

“…The quality, yield, and morphological characteristics of sugar beet were all improved by proline application. White sugar yields were also raised (Altaf, 2023).…”