Growth promotion in chard, carrot and radish plants by Pseudoxanthomonas indica named H32

Abstract

One of the main problems in current agriculture is the reduction of chemical fertilizers by replacing them with biofertilizers composed of beneficial microorganisms for soils and plants. Therefore, the present work aims to evaluate the effect of Pseudoxanthomonas indica named H32, previously isolated from healthy tomato plants rhizosphere, on the growth, development and yield of chard, carrot and radish crops. To this end, its ability to produce indoleacetic acid (IAA) was determined. In addition, its property to solubilizing insoluble phosphate in Pikovskaya-agar medium. The seeds were inoculated by soaking in a H32 cells suspension with 10⁵ UFC/mL in 0.1 % carboxymetyl cellulose solution, for 3 h.  A similar procedure using only carboxymetyl cellulose solution was done for non-inoculated seeds. All Seeds were then sown in 1 x 10 m plots. H32 was inoculated around the root of the seedlings of inoculated seeds, seven days after germination. The results showed that plants from inoculated seeds had greater humid weight, greater height, and roots with greater length and weight than plants from non-inoculated seeds (P < 0.01). The inoculation of the seeds and soil with H32 increased the yield by 19 % for radish, 88.7 % and 68.5 % for chard and carrot, respectively. These results show that Pseudoxanthomonas indica H32 has potential for use as a growth promoter in the crops studied.