Interactive Effects of K-Humate, Proline and Si and Zn Nanoparticles in Improving Salt Tolerance of Wheat in Arid Degraded Soils

Silicon (Si) and zinc (Zn) nanoparticles (NPs) and foliar application of proline have been used in alleviating salt stress and enhancing wheat productivity, but the effectiveness of these materials may be enhanced when supplying the sandy degraded soil with organic amendments, e. g., potassium humate (KH). The response of wheat to spraying with a mixture of proline and NPs of Si and Zn in the presence of soil additions of KH needs further clarification, especially in low fertile sandy soils. A split-plot design with three replicates was used to carry out a two-season field experiment in a sandy saline soil (11 dS m−1). The K-humate doses (0, 10, and 20 kg ha−1) were placed in the main plots, while the foliar spraying of proline and NPs were placed in the subplots. The foliar spraying treatments were: water, proline, Si NPs, Zn NPs, Si + Zn NPs, and proline + Si + Zn NPs. The obtained results showed that the soil organic matter (SOM) significantly increased by 13% when K-humate was added at the dose of 20 kg ha−1. The addition of 20 kg ha−1 of K-humate improved the soil's available N, P, and K by 38, 67, and 21% and enhanced the uptake of these nutrients by 6, 13, and 12%, compared to the non-amended soil. Grain, straw, and biological yield increased by 26, 45, and 38%, respectively, when the K-humate increased from 0 to 20 kg ha−1. The grain, straw, and biological yield increased by 21, 26, and 24%, respectively, as a result of foliar spraying of proline + Si + Zn NPs. The addition of K-humate (20 kg ha−1) enhanced the leaf chlorophyll and boosted the K+/Na+ ratio by 36%, compared to the control. Chlorophyll and proline levels in wheat leaves were markedly raised by foliar application of proline and Si and Zn NPs. The soil application of K-humate and the exogenous application of proline improved the effectiveness of Si and Zn NPs in minimizing the adverse effects of salt stress. It is not recommended to only apply silicon and zinc nanoparticles via foliar spraying; an integrated parenteral management plan that depends on the addition of organic amendments to the saline sandy soils is also required.