Effectiveness of ACC-deaminase containing Pseudomonas strains to induce salinity tolerance in maize under fertilized and unfertilized field conditions

Salinity inhibits plant growth and yield due to endogenous production of higher levels of ethylene. Some rhizobacteria contain an enzyme ACC-deaminase that has the ability to cleave ACC, the precursor of ethylene thus reducing the deleterious effects of salinity on plant growth. In the present study, two rhizobacterial strains [Pseudomonas fragi (P1) and Pseudomonas fluorescens (P2)] were evaluated for their effectiveness to reduce the hazardous effects of salinity on maize under fertilized and unfertilized field conditions. Results showed that both the strains significantly improved maize growth and yield especially when inoculated in the presence of recommended levels of NPK fertilizers. In the absence of chemical fertilizers, the increase in root length, shoot length, grain yield, straw yield, and nitrogen, phosphorus and potassium contents in maize grain and stalk due to inoculation was found to be up to 30, 19, 8, 9, 5, 8, 3, 10, 3 and 5%, respectively, as compared to control. On the other hand, the improvement in all above mentioned parameters was up to 94, 90, 53, 55, 32, 28, 37, 40, 26 and 29%, respectively, as compared to the control when inoculated with same bacterial strains in the presence of recommended levels of chemical fertilizers. It may be concluded that efficacy of microbial inoculants can be increased under salt-affected field conditions when applied in the presence of recommended levels of chemical fertilizers.