Plant Growth Promoting Rhizobacteria and Silicon Synergistically Enhance Salinity Tolerance of Mung Bean

Abstract

The present study explored the eco-friendly approach of utilizing plant-growth-promoting rhizobacteria (PGPR) inoculation and foliar application of silicon (Si) to improve the physiology, growth, and yield of mung bean under saline conditions. We isolated 18 promising PGPR from natural saline soil in Saudi Arabia, and screened them for plant-growth-promoting activities. Two effective strains were selected from the screening trial, and were identified as Enterobacter cloacae and Bacillus drentensis using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry and 16S rRNA gene sequencing techniques, respectively. Subsequently, in a 2-year mung bean field trial, using a randomized complete block design with a split-split plot arrangement, we evaluated the two PGPR strains and two Si levels (1 and 2 kg ha−1), in comparison with control treatments, under three different saline irrigation conditions (3.12, 5.46, and 7.81 dS m−1). The results indicated that salt stress substantially reduced stomatal conductance, transpiration rate, relative water content (RWC), total chlorophyll content, chlorophyll a, chlorophyll b, carotenoid content, plant height, leaf area, dry biomass, seed yield, and salt tolerance index. The PGPR strains and Si levels independently improved all the aforementioned parameters. Furthermore, the combined application of the B. drentensis strain with 2 kg Si ha−1 resulted in the greatest enhancement of mung bean physiology, growth, and yield. Overall, the results of this study provide important information for the benefit of the agricultural industry.

Effect of Enterobacter sp. CS2 and EDTA on the Phytoremediation of Ni-contaminated Soil by Impatiens balsamina

“…CS2 inoculation improved quantity of carotenoid, chl 'a', and chl 'b' contents ( Table 2). The increased biomass production in inoculated plants may be credited to increased synthesis of carotenoids along with chl 'a' and chl 'b' [37][38]. Similarly, improved chl contents, growth, and biomass production was observed in inoculated Eruca sativa plants growing under Cd stress [39].…”

Pseudomonas knackmussiiMLR6, a rhizospheric strain isolated from halophyte, enhances salt tolerance inArabidopsis thaliana

“…; Mahmood et al . ). In this study, EL% was higher in control plants under stress conditions, indicating membrane damages due to osmotic effect.…”

“…The great reduction reported in the chlorophyll content in control plants under the salt stress is in line with previous studies (Mahmood et al . ; Panwar et al . ), stating that salinity negatively affects chlorophyll content and membrane stability of leaves.…”

Rhizosphere engineering: Enhancing sustainable plant ecosystem productivity

“…Under salinity stress, peanut seedlings were able to maintain ion homeostasis, had less ROS buildup with enhanced growth, compared to non-inoculated seedlings (Sharma et al, 2016). Another study by Mahmood et al, (2016) demonstrated that Enterobacter cloacae and Bacillus drentensis acted synergistically with foliar application of silicon to confer salinity tolerance in field-grown Mung beans. Moreover, Brachybacterium saurashtrense strain JG-06, Brevibacterium casei strain JG-08, and…”