Seeds Pretreatment with Zeatins or Maize Grain-Derived Organic Biostimulant Improved Hormonal Contents, Polyamine Gene Expression, and Salinity and Drought Tolerance of Wheat

The strategy of seed priming has been effectively addressed with plant extracts containing biostimulants for healthy growth and productivity of stressful plants. Therefore, the effect of maize grain extract (MGE) on wheat plant performance, hormones, polyamines (PAs) gene expression, and antioxidant system was examined under combined stress compared to synthetic cytokinins (CKs). Cis (c-Z) and trans-zeatin-type cytokinin (t-Z) were the synthetic CKs, and 75 mA/NaCl-salinity + 60% of soil water-holding capacity (SWHC) was the combined stress used in this study. C-Z or t-Z was applied as seed priming at 20 ILEM versus 2% MGE. Under normal conditions, c-Z, t-Z, or MGE pretreatment positively affected wheat growth, grain yield, photosynthetic efficiency, and the contents of soluble sugars, a-tocopherol, ascothate (AsA) and glutathione (GSH). The redox state of AsA and GSH, the contents of phytohormones, PAs and metabolism enzyme activity of proline, PAs gene expression, and enzymatic activities were also improved. In contrast, malondialdehyde (MDA) and H(2)O(2)contents were reduced compared to the control. Under the combined stress, negative effects were recorded on all above attributes including deleterious increases in Na+, Cl-, MDA, and H2O2 contents compared to the control. However, c-Z, t-Z, or MGE pretreatment alleviated the combined stress effects and significantly improved all above attributes including significant decreases in Na+, Cl-, MDA, and H2O2 contents compared to the stressed control. Compared to c-Z or t-Z, seed priming using 2% MGE conferred better results. Therefore, MGE is recommended to promote wheat growth and grain yield by reducing the influences of deficit saline irrigation water-induced oxidative stress. (C) 2020 Friends Science Publishers