Plant Growth Promoting Rhizobacteria Having 1-Aminocyclopropane-1-Carboxylic Acid Deaminase to Induce Salt Tolerance in Sunflower (<i>Helianthus annus L.</i>)

Abstract

Soil salinity badly affects agriculture productivity through accumulation of salts in upper layers of soils. The harmful effects of salts in arable lands have influenced modern as well as ancient civilizations. A pot study was carried out to test the performance of two PGPR isolates (KS 8, KS 28) on sunflower (SMH-0917) under different salinity levels (8, 10 and 12 dS·m -1 ). These salinity levels were developed by adding calculated amount of salts (NaCl, Na 2 SO 4 , CaCl 2 and MgSO 4 ) with ratio of 3:4:2:1. The bacterial strains KS 8 and KS 28 were applied separately in two treatments while third treatment was co-inoculation (KS mix). Completely randomized experimental design (CRD) was used and data were collected at flowering stage about pre-decided plant growth parameters (plant height, shoot dry weight and root dry weight). The bacterial isolate KS 8 showed an increase of 26, 102% and 83% in plant height, shoot dry weight and root dry weight at EC 8 dS·m -1 , while this improvement was 67%, 163% and 296% at EC 10 dS·m -1 , however an increase of 100%, 74% and 382% was recorded over control respectively at EC 12 dS·m -1 . Similarly isolate KS 28 exhibited an increase of 14%, 69% and 54% in plant height; shoot dry weight and root dry weight at EC 8 dS·m -1 , whereas this improvement was 56%, 163% and 188% at EC 10 dS·m - 1 , while an increase of 60%, 41% and 282% was registered respectively over control at EC 12 dS·m -1 . The increase due to mixture treatments was 4%, 41% and 16% in plant height, shoot dry weight and root dry weight at EC 8 dS·m -1 , while an increase of 33%, 57% and 100% at EC 10 dS·m - 1 , whereas an improvement of 53%, 33% and 164% respectively was noted at EC 12 dS·m -1 over un-inoculated. The isolate KS 8 performed better than KS 28 and mixture treatment. These two PGPR strains could be used to mitigate the adverse impact caused by salinity stress on sunflower.