Effect of Trichoderma harzianum and Pseudomonas fluorescens on the Enhancement of Drought Tolerance and Plant Growth in Tomato

In the present study, different isolates of Trichoderma harzianum and Pseudomonas fluorescens were evaluated for the induction ofdrought tolerance and growth promotion in tomato plants. Four isolates of Pseudomonas fluorescens viz Pf 2 Pf 4, Pf 6 and Pf 28 and three isolates of Trichoderma harzianum viz. TH 08, IRRI 1 and TH 26 were evaluated by using seed biopriming as well as seedling/transplanted root dip method against drought stress and for their effect onplant growth promotion. Parametersincludingdrought tolerance capacity, water requirement, shoot length, root length, plant height, and chlorophyll content were recorded inall the treatments of different isolates along with the untreated control.Among the two methods of bioinoculation, seed biopriming was found more effective to transplanted root dip in all the treatments of isolates of Trichoderma harzianum and Pseudomonas fluorescens. Among all the isolates, isolate IRRI 1 of Trichoderma harzianum was found highly effective in reducing the water stressbyincreasing thecumulative mean water stresstolerance duration of both methods of inoculation up to 14.83 days after the last irrigation with least mean water requirement of 13.92litres followed by isolate Pf28 of Pseudomonas fluorescens with mean water stress tolerance of 13.66 days and water requirement of 14.25 litres compared to the untreated control plants with least tolerance ofonly 10.66 days and highest water requirement of 16.25litres. Maximum cumulative mean shoot growth, root growth and chlorophyll content ofboth methods of inoculation of 76.25cm, 28.33cm and 41.20 SPAD units respectively were also recorded with IRRI 1 isolate followed by Pf 28 isolate with 67.17cm, 19cm, and 35.46 SPAD units respectively. Treatment with all other isolates of Trichoderma harzianum and Pseudomonas fluorescens also showed better water stress tolerance, less water consumption, increased shoot length, root length and chlorophyll content compared to the untreated control tomato plants.