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

Abstract

The continuity of traditional planting systems in the last few decades has encountered its most significant challenge in the harsh changes in the global climate, leading to frustration in the plant growth and productivity, especially in the arid and semi-arid regions cultivated with moderate or sensitive crops to abiotic stresses. Faba bean, like most legume crops, is considered a moderately sensitive crop to saline soil and/or saline water. In this connection, a field experiment was conducted during the successive winter seasons 2018/2019 and 2019/2020 in a salt-affected soil to explore the combined effects of plant growth-promoting rhizobacteria (PGPR) and potassium (K) silicate on maintaining the soil quality, performance, and productivity of faba bean plants irrigated with either fresh water or saline water. Our findings indicated that the coupled use of PGPR and K silicate under the saline water irrigation treatment had the capability to reduce the levels of exchangeable sodium percentage (ESP) in the soil and to promote the activity of some soil enzymes (urease and dehydrogenase), which recorded nearly non-significant differences compared with fresh water (control) treatment, leading to reinstating the soil quality. Consequently, under salinity stress, the combined application motivated the faba bean vegetative growth, e.g., root length and nodulation, which reinstated the K+/Na+ ions homeostasis, leading to the lessening or equalizing of the activity level of enzymatic antioxidants (CAT, POD, and SOD) compared with the controls of both saline water and fresh water treatments, respectively. Although the irrigation with saline water significantly increased the osmolytes concentration (free amino acids and proline) in faba bean plants compared with fresh water treatment, application of PGPR or K-silicate notably reduced the osmolyte levels below the control treatment, either under stress or non-stress conditions. On the contrary, the concentrations of soluble assimilates (total soluble proteins and total soluble sugars) recorded pronounced increases under tested treatments, which enriched the plant growth, the nutrients (N, P, and K) uptake and translocation to the sink organs, which lastly improved the yield attributes (number of pods plant−1, number of seeds pod−1, 100-seed weight). It was concluded that the combined application of PGPR and K-silicate is considered a profitable strategy that is able to alleviate the harmful impact of salt stress alongside increasing plant growth and productivity.

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

“…The combined soil and foliar application of PGPMs and Si-ZnNPs, respectively, boosted the performance of the soybean plant to its maximum capacity, which reduced the ESP in the soil to 32.5% lower than control, while nodule DW increased by 19.1%, root length by 28.6%, and leaves area plant −1 by 36.3% over control ( Figure 1 ). These positive findings are in agreement with our previous work on faba bean [ 25 ], where the dual application of PGPR and silica recorded heavier nodule dry weight and root length.…”

“…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.…”

Quinoa Response to Application of Phosphogypsum and Plant Growth-Promoting Rhizobacteria under Water Stress Associated with Salt-Affected Soil

“…However, the high efficiency of PGPR could be due to its ability to give high seedling vigor with a free radical defense system [ 55 ]. In this concern, soil applications are found to augment the growth and yield of higher plants, particularly under abiotic stress [ 56 , 57 ]. Soil microorganisms shape global element cycles in life and death.…”

Soil Amendment Using Biochar and Application of K-Humate Enhance the Growth, Productivity, and Nutritional Value of Onion (Allium cepa L.) under Deficit Irrigation Conditions

“…Onion plants exposed to water stress under salt-affected soil reduce the plant growth and development by interrupting various physiological characteristics, such as total chlorophyll, carotenoids, stomatal conductance, and relative water content in addition to biochemical properties like total amino acids, proline content, and total soluble sugars [25]. In the current study, it was found that total chlorophylls, carotenoids, stomatal conductance, relative water content, and total soluble sugars were significantly increased and total amino acids and proline content decreased due to the important role of dual application of soil amendment with biochar and foliar spraying with potassium humate which had the potentiality to stimulate the meristematic activity which increases cell division and enlargement [26,27].…”

“…Nutritional contents of onion were enhanced in potassium humate applied as the presence of biochar could have resulted in improved phenolic compound synthesis [28] which has to been linked to a positive relation between bulb carbohydrate, bulb soluble sugars, bulb protein, bulb flavonoid contents and potassium humate applied on onion. Bulb carbohydrate, bulb soluble sugars, bulb protein, and bulb flavonoid contents rely upon transported ions and organic solutes that are converted into glucose inside onion [17,25] where biochar and potassium humate application enhances glucose biosynthesis, contributing to improved quality traits in onion plants.…”