Effect of Growth-promoting Bacterial Consortia on Overall Growth of Tomato Plants

Abstract

The present work was focused on plant growth-promoting bacteria (PGPB) for the enhanced production of tomatoes. The effect of 14 indigenous PGPB isolated from the soil samples collected from Gir National forest areas (Dist. Junagadh, Gujarat, India) and the coastal region of Saurashtra (Dist. Gir-Somnath, Gujarat, India) on tomato seedlings was studied. Only 6 isolates showed positive results in in vitro biochemical and plant-growth-promoting assays such as phosphate and zinc solubilization, siderophores and HCN production and antibacterial and antifungal properties. The rest isolates were negative to one or more of the selected tests. Based on in vitro results, all PGPB were tested on tomato seedlings. Four stage screenings were used to select the best combinations. After the primary screening, 9 isolates were selected for further experiments based on the germination, height of plants and seedling vigor. Plant height, leaf count, seedling vigor and total chlorophyll were measured. Leaf anatomy was studied at the end of the quaternary trial to understand the changes at a cellular level and it revealed the anatomical changes such as increased chlorophyll at cellular level and enhanced starch production. Microbial consortia showed better results compated to single-inoculant treatment. Out of 503 different combinations tested at secondary trial, 129 were selected for tertiary trials and 24 from them were further qualified for quaternary trials. At the end of quaternary trials, total 04 combinations were selected for future experiments on field. The quaternary trial strategy helped to reduce the total 503 possible combinations to 04 combinations improving germination, height, seedling vigor, number of leaves and chlorophyll content compared to non-treated tomato plants. Further trials were carried out in field for long period of time to measure the profound effect of selected consortium in real life.