Enhancing maize (Zea mays L.) tolerance to water stress using kaolin and potassium silicate as protective agents

The application of potassium silicate fertilizers in agricultural sector is emerging as an efficient strategy in managing the effects of water stress on various crops. The current research investigates the protective role of silicon forms, namely kaolin (Al₄Si₄O₁₀ (OH)₈) and potassium silicate (K₂SiO₃) in alleviating the harmful impacts of water-deficit stress on maize. There are not sufficient reports on the protective role of these two silicon forms in alleviating water stress in maize. Maize genotypes: R-2315 (tolerant) and R-2317 (susceptible) were grown in plastic pots and water stress (60% field capacity) was applied at silking stage for 7 days. After imposition of water stress, 4% kaolin and 0.06% K₂SiO₃ was sprayed on plants. After 14 days of application of kaolin and K₂SiO₃, samples were collected. Under water stress, the treatment of kaolin and K₂SiO₃ significantly (p ≤ 0.001) enhanced the shoot length, root length, shoot fresh weight, root fresh weight, shoot dry weight, root dry weight, in both maize genotypes (R-2315 and R-2317). Furthermore, applications of kaolin and K₂SiO₃ significantly improved stomatal conductance (g_s), rate of photosynthesis (A), transpiration rate (E), and relative water contents (RWC) under applied water stress. Treatments of kaolin and K₂SiO₃ also showed a significant decrease in oxidative stress parameters like malondialdehyde, relative membrane permeability and hydrogen peroxide (H₂O₂) contents by increasing activities of enzymatic antioxidants such as peroxidase, catalase and superoxide dismutase, non-enzymatic antioxidant (anthocyanins, flavonoids, ascorbic acid), and osmolytes (proline, total free amino acids, total soluble proteins, anthocyanin), under water deficit stress. Conclusively, among treatments and genotypes, application of K₂SiO₃ and R-2315 showed maximum improvement in growth, morphological and biochemical attributes under water stress. These findings demonstrated that kaolin and K₂SiO₃ foliar application could be adapted as an effective strategy to control the negative impacts of water stress in crops.