1Department of Plant Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan
2Department of Botany, University of Okara, Okara 56300, Pakistan
3Land Resource Research Institute, NARC, Islamabad 44000, Pakistan
Abstract
Two planned studies (Isolation, characterization, and field studies) were piloted to assess the potential of heat-tolerant plant growth promoting bacteria (PGPB) to mitigate heat stress in the tomato plant. . The production of indole acetic acid (IAA), phosphate, solubilization and ammonia, as well as siderophores, hydrogen cyanide (HCN), extracellular enzyme activity (protease, amylase, pectinase, and catalase), ACC-deaminase, and exopolysaccharide synthesis, were all positively confirmed in the isolate. The selected strain was screened at high temperature of 60 0C. The promising potential heat-tolerant isolate was further identified through 16S rRNA gene sequencing technique and Acds gene was also successfully amplified. Morphological characterization revealed that strain was Gram positive. B. safensis (T6) strain showed higher quantity of Gibberellic acid (8.73 μg/ml) and Kinetin (34.8 μg/ml) under heat stress condition. The results of morpho-physiological parameters revealed significant effects of heat on un-inoculated and inoculated tomato plants under high temperature stress. Multi-year/multi-location field trials were done to extend studies of heat mitigation effects after encouraging results by bacterial strains. Plant growth promoting bacteria (PGPB) improved agronomic and yield metrics of tomato plants under heat stress in all field studies. First year 2018 & 2019 field trials at National Agriculture Research Centre, Islamabad, Pakistan showed that Bacillus safensis (T6) produced the maximum number of flower’s (40.7 %) and fruits (24.8%) in 2018 and number of flowers (43 1%) and fruits (11.03%) in 2019 while the consortia treatments produced maximum flowers (16.9%) and fruits (52.1 %), respectively. The current study comprehensively exhibited the role of PGPB in the mitigation of heat stress.
