Inoculation Effects of Potassium Releasing Bacteria on K Nutrition of Tomato in Sand-Muscovite Medium and Identification of Efficient Isolates

Attention to the potassium releasing bacteria is due to high demand of plants to this element. Therefore, in this study the effects of 15 bacterial isolates (S5-5, S5-9, S6-6, 10-3, S11-2, S12 -3, S14-1, S14-3, S15-1, S16-3, S17-4, S19-1, S19-2, S20-7 and S21-1) and Pseudomonas putida strain P13 on the growth and potassium nutrition of tomato were assessed. The experiment was performed under sterile condition in a bed of sand and Muscovite and other nutrients, except potassium, during the growing season were supplied through Hoagland solution. The results showed that the application of the 16 isolates didnt affect the wet and dry weight of shoot and the concentration and content of root potassium but the plant height, wet and dry weight of root, total dry weight of plant, concentration and content of shoot potassium and the concentration and content of root phosphorus significantly increased in some isolates in comparison to the un-inoculated treatment. The highest height of the plant with an increase of 16.56% compared to the uninoculated control was observed in the isolate S21-1 (48.08 cm). The highest total dry weight of plant was measured with the strain S19-1 (6.35 g pot-1) and maximum concentration of potassium in shoot (14.3 mg g-1) was observed in the isolate S10-3. The most content of the shoot potassium (78.67 mg pot-1) gained in isolate S10-3 which in comparison with the non-bacterial control showed an increase of 70 %. Molecular and biochemical identification results (16S rDNA) showed that efficient isolates belonged to the genus Pseudomonas.