The effect of different bacteria (pseudomonas fluorescens, bacillus megaterium and bacillus subtilis) applications on drought tolerance of guar (Cyamopsis Tetragonoloba (l.) taub.)

Drought is one of the most important environmental factors limiting plant growth and development. Nowadays, especially in the context of increasing productivity, a number of applications are carried out with microorganisms of biological origin, more useful in agricultural production. In this study, effects of different bacteria applications on drought tolerance were evaluated. Guar (Cyamopsis tetragonoloba (L.) Taub.) seeds, which are came from the India was used as the material. The guar seedlings were grown in 12-L plastic pots containing a 2:1 ratio of peat to perlite medium and housed in a greenhouse that was maintained at day/night temperatures of 26 ± 2 °C and 18 ± 2 °C, and a relative humidity of 65% ± 5. When plants reached 3th leaf (15-20 cm height), drought and bacteria applications were started. For drought stress; 100% (K), 75 (D1), 50 (D2), 25 (D3) and 0 (D4) levels of the field capacity were taken for stress levels; 100% irrigation was accepted as the control application. Three different bacterial species (Pseudomonas fluorescens (PF), Bacillus megaterium (BM) and Bacillus subtilis (BS)) were used in the study. Starting from 30DAS, the drought treatment began and, the plants were evaluated in terms of fresh and dry weight, plant height, stem diameter, number of leaves, leaf area, root fresh and dry weight, chlorophyll (SPAD), relative water content, leaf water potential, and membrane injury index. As a result of the study; D4 (0%) irrigation applications adversely affected the plant growth and, 25-71% decrease was observed in terms of the parameters (fresh and dry weight, plant height, stem diameter, number of leaves, leaf area, root fresh and dry weight), examined compared to control plants. Moreover compared to control plants, relative water content and SPAD reduced by 37% and %34, while membrane injury index and leaf water potential increased %19 and 280% (negative increase), respectively. However, bacterial applications increased tolerance of plants to drought stress and thedecrease in control plants remained at 3-35%. Application of bacteria increased drought tolerance especially D4 treatment and improvement drought tolerance for BS (3-71%), PF (28-159%), and BM (3-169%). According to our results; it was determined that Bacillus megaterium (BM) was more effective in drought tolerance, f