Abstract
Soil salinity has emerged as a major obstacle to meet world food demands. Halo-tolerant plant growth promoting rhizobacteria (PGPR) are potential bioinoculants to enhance crop productivity in saline agriculture. Current work was aimed at studying individual or synergetic impact of salt tolerant PGPR on wheat growth and yield under saline conditions. A pot experiment was conducted on two wheat genotypes (Aas-11; salt tolerant and Galaxy-13; salt sensitive) inoculated with Pseudomonas fluorescence, Bacillus pumilus, and Exiguobacterium aurantiacum alone and in consortium. The salt tolerant variety (Aas-11) exhibited maximum root fresh (665.2%) and dry biomass (865%), free proline (138.12%) and total soluble proteins (155.9%) contents, CAT (41.7%) activity and shoot potassium uptake (81.08%) upon inoculation with B. pumilus, while improved shoot dry weight (70.39%), water (23.49%) and osmotic (29.65%) potential, POD (60.51%) activity, enhanced root potassium (286.36%) and shoot calcium (400%) were manifested by E. aurantiacum. Highest shoot length (14.38%), fresh weight (72.73%), potassium (29.7%) and calcium (400%) acquisition as well as glycinebetaine (270.31%) content were found in plants treated with PGPR consortium. On the other hand, in the salt sensitive variety (Galaxy-13), P. fluorescens treated plants showed significantly improved leaf-water relations, glycinebetaine (10.78%) content, shoot potassium (23.07%), root calcium (50%) uptake, and yield parameters, respectively. Plant root length (71.72%) and potassium content (113.39%), root and shoot fresh and dry biomass, turgor potential (231.02%) and free proline (317.2%) content were maximum upon PGPR inoculation in consortium. Overall, Aas-11 (salt tolerant variety) showed significantly better performance than Galaxy-13 (salt sensitive variety). This study recommends B. pumilus and E. aurantiacum for the salt tolerant (Aas-11) and P. fluorescens for the salt sensitive (Galaxy-13) varieties, as potential bioinoculants to augment their growth and yield through modulation of morpho-physiological and biochemical attributes under saline conditions.
Highlights
Climate change, a hot topic of the current era, has affected planet earth in different ways and a rapid increase in saline landscapes is one of them that leads to global food insecurity and reduced agricultural productivity (Bharti et al, 2016)
The salt tolerant variety; Aas-11, showed substantial increase compared to the salt sensitive variety; Galaxy-13
Plants inoculated with E. aurantiacum (T4) and consortium of plant growth promoting rhizobacteria (PGPR) (T5) expressed a non-significant increase in root length compared to untreated control plants
Summary
A hot topic of the current era, has affected planet earth in different ways and a rapid increase in saline landscapes is one of them that leads to global food insecurity and reduced agricultural productivity (Bharti et al, 2016). Almost 70% yield loss has been reported among cereal crops including wheat, rice, maize, and barley due to soil contamination by salinity and sodicity (Rajendran et al, 2009; Hussain et al, 2019). Reclamation of such soils is being done by utilizing a variety of inorganic (gypsum, limestone, sulfuric acid and derivatives of sulfur, synthetic fertilizers), and organic (green and farm yard manure, industrial waste like press mud) measures (Qayyum et al, 2016). Plant breeders and biotechnologists are in a constant struggle for the development of salt tolerant crop varieties either through natural selection, QTL mapping, marker assisted selection or by genetic manipulation via introduction of salt tolerant genes obtained from other organisms (Qadir et al, 2017). At field level, due to multiple factors, satisfactory outcomes have not been observed by such biological means for stress tolerance enhancement among the agro-economical significant crops (Khare et al, 2018)
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