Integrative Soil Application of Humic Acid and Foliar Plant Growth Stimulants Improves Soil Properties and Wheat Yield and Quality in Nutrient-Poor Sandy Soil of a Semiarid Region

Abstract

Sandy soils (containing > 50% sand) are widely distributed worldwide and are characterized by their poor structure, low organic matter, weak hydraulic and nutritional properties, and low crop productivity. Using a 2-year pot experiment, in this study, we investigated the effects of humic acid (HA) as a soil amendment and study two plant growth stimulants (PGSs), zinc oxide nanoparticles (ZnONPs), and L-tryptophan (L-TRP), as a foliar application on wheat grown in nutrient-poor sandy soil. Three HA rates (0 (HA0), 0.2 (HA0.2), and 0.4 (HA0.4) g kg−1 soil) and five PGS levels [control, 50 mg l−1 (ZnONPs50), 100 mg l−1 (ZnONPs100), 0.25 mmol l−1 (L-TRP0.25), and 0.5 mmol l−1 (L-TRP0.5)] were used. The soil hydro-physico-chemical properties, morpho-physiological responses, yield, and quality were measured. HA addition amended the soil structure by allowing rapid macroaggregate formation, decreasing bulk density and pH, and increasing porosity and electrical conductivity, thereby improving soil hydraulic properties. HA0.2 and HA0.4 additions improved growth, yield components, and grain minerals, resulting in higher grain yield by 28.3–54.4%, grain protein by 10.2–13.4%, wet gluten by 18.2–23.3%, and dry gluten by 23.5–29.5%, respectively, than HA0. Foliar application of ZnONPs or L-TRP, especially at higher concentrations compared to the control, noticeably recorded the same positive results as HA treatments. The best results were achieved through the integration of HA0.4 + ZnONPs100 or L-TRP0.5 to the tested nutrient-poor sandy soil. The interactive application of HA0.4 + ZnONPs100 or L-TRP0.5 and the use of mineral fertilizer, which is considered a surplus point in permaculture, can be recommended for sustainable wheat production in nutrient-poor sandy soil.

Biologically Oriented Hybrids of Indole and Hydantoin Derivatives

“…As model compounds, we have chosen some synthesized derivatives of 3-(2-oxoimidazolidine-5-yl)indole 3 to study growth-regulating activity. Known auxins [ 49 , 50 , 51 , 52 , 53 ]—derivatives of indole, namely indolylacetic (IAA) and indolebutyric (IBA) acids, as well as L-tryptophan (Trp)—were selected as compounds for comparison.…”

“…It is known that derivatives of indole auxins are phytohormones. They affect the growth and development of plants and increase their resistance to the environment [ 49 , 50 , 51 , 52 , 53 ]. For example, indolylacetic (IAA) and indolebutyric (IBA) acids act as growth regulators, stimulate root formation [ 54 , 55 , 56 ], flower development, and fruit growth [ 57 ], and help plants overcome stress [ 58 ].…”

“…For example, indolylacetic (IAA) and indolebutyric (IBA) acids act as growth regulators, stimulate root formation [ 54 , 55 , 56 ], flower development, and fruit growth [ 57 ], and help plants overcome stress [ 58 ]. Tryptophan improves plant resistance to Cd, reduces its accumulation in the biomass [ 59 ], and increases yields in nutrient-deficient soils [ 53 ]. Indole derivatives with fungicidal activity, such as streptochlorin, are well-known [ 28 , 30 ].…”

Bread Wheat Productivity in Response to Humic Acid Supply and Supplementary Irrigation Mode in Three Northwestern Coastal Sites of Egypt

“…Furthermore, previous authors [59,[71][72][73] mentioned that HA increased the levels of 40 compounds that are associated with the stress response. HA molecules promote the osmotic adjustment ability, increase leaf water retention, as well the photosynthetic and antioxidant metabolism of plants under drought stress [74,75]. The integration of HA application and a water deficit makes it possible to assess the precision and efficiency of the system in researching the effect of HA on drought tolerance [45,76].…”

Exploring the Potential Enhancing Effects of Trans-Zeatin and Silymarin on the Productivity and Antioxidant Defense Capacity of Cadmium-Stressed Wheat

“…Wheat is an essential strategic crop worldwide and the expansion of its cultivation contributes greatly to ensuring human food security. However, it is sensitive to various eco-stressors [ 20 ], including HMs stress [ 3 , 21 , 22 , 23 ]. It is a staple food crop and contributes to feeding more than 50% of the world’s population [ 24 ].…”