Phosphate-solubilizing and plant-growth-promoting Pseudomonas aeruginosa PS1 improves greengram performance in quizalafop-p-ethyl and clodinafop amended soil.

The quizalafop-p-ethyl- and clodinafop-tolerant phosphate-solubilizing and plant-growth-promoting Pseudomonas aeruginosa PS1 isolated from the rhizospheric soils of mustard was used to determine its phosphate-solubilizing activity and other plant-growth-promoting traits both in the presence and absence of technical grade quizalafop-p-ethyl and clodinafop under in vitro conditions. Quizalafop-p-ethyl (at 40, 80, and 120 ppb) and clodinafop (at 400, 800, and 1200 ppb) reduced the P-solubilizing activity, synthesis of indole-3-acetic acid, and siderophores progressively with increasing concentrations of each herbicide. Hydrogen cyanide and ammonia synthesisized by this strain, however, did not change. Furthermore, the effects of three concentrations each of quizalafop-p-ethyl [40 (recommended dose), 80, and 120 ppb] and clodinafop [400 (recommended dose), 800, and 1200 ppb] were evaluated on plant-growth-promoting Pseudomonas aeruginosa strain PS1 inoculated greengram plants, grown in sandy clay loam soil. Generally, all of the concentrations of both quizalafop-p-ethyl and clodinafop showed phytotoxicity and severely affected the growth, symbiosis, grain yield, and nutrient uptake by greengram plants. The toxicity of quizalafop-p-ethyl and clodinafop enhanced gradually with the increase in the dose rate of herbicides. Quizalafop-p-ethyl was more toxic than clodinafop. In contrast, herbicide-tolerant P. aeruginosa strain PS1 when used with herbicides increased the measured parameters at all concentrations. Both quizalafop-p-ethyl at 120 ppb and clodinafop at 400 ppb increased total chlorophyll content, leghemoglobin, root N, shoot N, root P, shoot P, seed yield, and seed protein, relative to the uninoculated control. The study suggests that the phytotoxicity of herbicides to legumes could be reduced by applying the growth-promoting herbicide-tolerant strain of Pseudomonas aeruginosa PS1.