Foliar-Applied Zinc is Beneficial to Growth, Grain Yield, and Quality of Standard and Ancient Wheats Grown under Saline and Non-Saline Conditions

Ancient wheats are valuable genetic resources, though knowledge on their response to micronutrients in the presence of saline irrigation water is scanty. Two studies were conducted to unravel the behavior of ancient emmer and spelt wheats upon exposure to saline (75 and 150 mM NaCl) water and foliar-applied Zn (4 g L^− 1) under pot and field conditions. Two weeks after implementing the salt treatment, Zn treatment was implemented twice with one week interval and the plants were exposed to the prolonged salt stress until physiological maturity. Then, an array of physiological processes underlying differential grain yield and quality responses of the ancient and standard wheats to these treatments were scrutinized. Salinity suppressed chlorophyll, relative water content, root volume, stubble yield, and grain yield of emmer and spelt and standard durum and bread wheats. Though, it increased the proline concentration, and Na⁺/K⁺ in all wheat genotypes. Emmer wheats indicated smaller salt-induced suppressions in stubble yield and grain yield, despite indicating a greater Na⁺/K⁺. Ancient emmer and spelt wheats indicated smaller grain yield components, but out-ranked the standard durum and bread wheats in terms of root volume, grain Zn, and protein concentrations. Zn’s effect on the grain yield attributes and grain yield was moderate but it enhanced the grain Zn, particularly in emmer wheats. Novel findings of this study suggest that emmer wheats supplied with foliar-applied Zn are superior to standard durum and bread wheats in terms of grain protein and Zn, root volume, and tolerance to saline water.