Minimizing the Adversely Impacts of Water Deficit and Soil Salinity on Maize Growth and Productivity in Response to the Application of Plant Growth-Promoting Rhizobacteria and Silica Nanoparticles

Abstract

The development of new approaches for sustaining soil quality, leaf health, and maize productivity are imperative in light of water deficit and soil salinity. Plant growth-promoting rhizobacteria (PGPR) and silica nanoparticles (SiNP) are expected to improve soil chemistry leading to improved plant performance and productivity. In this field experiment, water deficit is imposed by three irrigation intervals—12 (I1), 15 (I2), and 18 (I3) days. Plants are also treated with foliar and soil applications (control, PGPR, SiNP, and PGPR + SiNP) to assess soil enzymatic activity, soil physicochemical properties, plant physiological traits, biochemical analysis, nutrient uptake, and productivity of maize (Zea mays L.) plants grown under salt-affected soil during the 2019 and 2020 seasons. With longer irrigation intervals, soil application of PGPR relieves the deleterious impacts of water shortage and improves yield-related traits and maize productivity. This is attributed to the improvement in soil enzymatic activity (dehydrogenase and alkaline phosphatase) and soil physicochemical characteristics, which enhances the plants’ health and growth under longer irrigation intervals (i.e., I2 and I3). Foliar spraying of SiNP shows an improvement in the physiological traits in maize plants grown under water shortage. This is mainly owing to the decline in oxidative stress by improving the enzymatic activity (CAT, SOD, and POD) and ion balance (K+/Na+), resulting in higher photosynthetic rate, relative water content, photosynthetic pigments, and stomatal conductance, alongside reduced proline content, electrolyte leakage, lipid peroxidase, and sodium content under salt-affected soil. The co-treatment of SiNP with PGPR confirms greater improvement in yield-related traits, maize productivity, as well as nutrient uptake (N, P, and K). Accordingly, their combination is a good strategy for relieving the detrimental impacts of water shortage and soil salinity on maize production.

Foliar-Applied Potassium Silicate Coupled with Plant Growth-Promoting Rhizobacteria Improves Growth, Physiology, Nutrient Uptake and Productivity of Faba Bean (Vicia faba L.) Irrigated with Saline Water in Salt-Affected Soil

“…Inoculation using Rhizobium leguminosarum biovar viciae (TAL-1148) and Bacillus circulans NCAIM B.02324 has excellent potential for nitrogen cycling, which in turn increase soil urease and dehydrogenase activities (Figure 1). The maximum soil enzyme activity can be associated with heavier nodules and deeper root length due to the enhancing of root and plant growth through soil nutrient enrichment, which improves the root exudates in the rhizosphere and consequently enlarging the microbial community [30,43]. The inoculation of PGPR strains positively affected modifications in root morphogenesis and augmented lateral root length and the density of root hairs, which are closely associated with the production of phytohormones, including auxins, cytokinins, and gibberellins [44].…”

“…Additionally, irrigation of faba bean plants with saline water caused modifications in biochemical constituents of salinity stressed faba bean plant alongside with the lessening in physiological processes which restrained photosynthetic activity, a decline of carbon dioxide in intercellular spaces of stomata, lowering the level of 3-phosphoglycerate and reducing the starch synthesis [58,59]. PGPR application promoted the synthesis of total soluble proteins and total soluble sugars, meanwhile decreased the levels of proline and free amino acids in faba bean plants irrigated with saline water, which may be directed from the surplus hormones synthesized by PGPR, leading to an increase in the levels of endogenous phytohormones like IAA and cytokinins, which stimulate the developmental processes related to anabolic pathways, like carbohydrates and proteins synthesis [30,60]. The foliar application of K-silicate promoted the concentrations of proline, amino acid, soluble protein, and soluble sugars, in addition to the biosynthesis of endogenous hormone that promoted cell division and cell enlargement of faba bean plants [61], an increase in nutrient uptake [62], IAA and cytokinins production [63].…”

“…Potassium silicate could improve yield-related traits, seed yield and quality, and nutrient (N, P, and K) uptake [24]. Some reports have shown that potassium silicate effectively affects plant development, production, and quality [30,31]. As a consequence, enhancing the activities of enzymatic antioxidants during salinity stress retains the plasma-membrane functions, e.g., controlling the permeability, which contributes to higher root activity, strengthening the root's ability to acquire the necessary nutrients [32,33].…”

Interactive Impacts of Beneficial Microbes and Si-Zn Nanocomposite on Growth and Productivity of Soybean Subjected to Water Deficit under Salt-Affected Soil Conditions

“…Remarkable studies have been conducted on the growth and productivity of crops grown under drought and salinity stress, and significant applications have been evaluated for their ability in improving the growth and development of field crops cultivated under drought and salinity stresses, which consider as an innovative approach for sustainable agriculture [ 21 , 22 , 23 , 24 , 25 ]. Beneficial microorganisms in the rhizosphere have positive effects on plant growth and development.…”

Agro-Waste Mediated Silica Nanoparticles and Their Application to Sustainable Agriculture

“…Application of different nanoparticles has resulted in numerous literatures with enhanced growth and development, crop production and resistance against different stresses on plants. Nowadays, silica nanoparticles (SiNPs)are utilized as a major source of Si and has achieved an astonishing position in agricultural sector because of its large surface area and small size, that assures favorable diffusion of SiNPs into root tissues (Hafez et al, 2021). On the basis of their sizes, content and treated plant varieties, SiNPs might behave as positive or negative in uence on ora.…”