Salt-tolerant plant growth-promoting bacteria enhanced salinity tolerance of salt-tolerant alfalfa (Medicago sativa L.) cultivars at high salinity

Abstract

Alfalfa (Medicago sativa L.) plant growth decreases when cultivated under salinity or irrigated with salty water. Inoculation with plant growth-promoting bacteria (PGPB) is a method for mitigating the harmful effects of salinity on plants growth. To investigate salt-tolerant PGPB with salt-tolerant and salt-sensitive alfalfa cultivar interactions under salinity, some physiological and agronomical aspects were investigated. The inoculated plants of alfalfa cultivars with Hartmannibacter. diazotrophicus and Pseudomonas sp. bacteria were compared with non-inoculated plants. Plants were grown in growth room and irrigated with tap water until 6-7 weeks, and then, salinity stress imposed by irrigating with tap water (control), 10 dS m −1 and 20 dS m −1 NaCl. Salinity reduced relative water content (RWC), membrane stability index (MSI), K + , photosynthesis rate (Pn) and stomatal conductance (gs), leaf number, height, and dry weight, and increased sodium in all cultivars. Inoculation of cultivars with both PGPB mitigated the negative effects of salinity on plants growth by increasing the root length and weight, nodule number, chlorophyll pigments, RWC, MSI, Pn, and gs. Chlorophyll pigments, plant height and leaf number, Na + , K + /Na + , and nodule number improved more pronounced through inoculating with Pseudomonas sp., whereas K + , carotenoids, and RWC improved more pronounced through H. diazotrophicus under salinity. The results showed inoculation with two bacteria improved growth performance in salt-tolerant and salt-sensitive cultivars under 10 dS m −1 , but at high salinity (20 dS m −1), inoculation was successful only in salt-tolerant alfalfa cultivars.

Effect of foliar and soil application of plant growth promoting bacteria on growth, physiology, yield and seed quality of maize under Mediterranean conditions

“…As far as the stomatal conductance is concerned (Table 7), the use of PGPB gave statistically significant differences at 52 and 88 DAS, while the method of application gave statistically significant differences at all three measurements (p < 0. www.nature.com/scientificreports/ Photosynthetic rate and stomatal conductance was higher in alfalfa plants inoculated with PGPB compared to control under normal and salinity conditions 34 . The inoculation of Herbaspirillum seropedicae in a field experiment of maize resulted in increased values of photosynthesis rate, stomatal conductance and transpiration rate of plants compared to the control 35 www.nature.com/scientificreports/ significant different.…”

Effects of Plant Growth Promoting Rhizobacteria on the Content of Abscisic Acid and Salt Resistance of Wheat Plants

“…In the case of salinity, the protective action of bacteria is due to an increase in the activity of the antioxidant system [ 5 ], accumulation of osmotically active substances and osmoprotectors [ 6 ], maintenance of ionic homeostasis [ 7 ], and direct action of bacteria on plant growth explained by their ability to produce growth stimulating plant hormones [ 4 ]. Along with these mechanisms, the bacteria-induced increase in salt tolerance is associated with their influence on plant water relations manifested in changes in the rate of transpiration [ 8 ]. Nevertheless, information about the influence of bacteria on the rate of transpiration is contradictory.…”

Dual Microbial Inoculation, a Game Changer? – Bacterial Biostimulants With Multifunctional Growth Promoting Traits to Mitigate Salinity Stress in Spring Mungbean

“…have been studied showing their favorable results on plant growth and for inducing salt stress tolerance in different crops (wheat, chickpea, alfalfa, soybean, mungbean, groundnut and tomato etc .) ( Panwar et al, 2016 ; Egamberdieva et al, 2017 ; Chandra et al, 2018 ; Saikia et al, 2018 ; Ansari et al, 2019 ; Gupta and Pandey, 2019a ; Khan and Bano, 2019 ; Vaishnav et al, 2019 , 2020 ; Goswami and Deka, 2020 ; Nagpal et al, 2020 ).…”