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.
Highlights
Salinity in agriculture is a global problem (Al-Karaki, 2006)
Our data suggest that the combined use of Si and plant-growth-promoting rhizobacteria (PGPR) is an effective approach for maximizing mung bean productivity on marginal land with saline water
In the first part of our study, 18 PGPR strains were tested for plant growth promoting (PGP) activities in mung bean
Summary
Owing to low rainfall and high evaporation in arid and semi-arid regions, salinity generates a low water potential in the soil, making it difficult for plants to acquire water, and resulting in water deficit conditions (Mahajan and Tuteja, 2005; Porcel et al, 2012). Salinity Tolerance in Mung Bean affects the physiology, growth, and yield of crops (Haghighi and Pessarakli, 2013; Liu et al, 2015). In soil and hydroponic culture, Si improved crop growth, and yield under various stresses (Haghighi and Pessarakli, 2013; Kochanová et al, 2014; Yin et al, 2014; Wang et al, 2015). Studies on the foliar application of Si have been conducted, no systematic research has explored its effects on physiology, growth, and yield of legume crops under saline stress in field conditions
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