Effects of phosphate-solubilizing bacteria during the rooting period of sugar cane (Saccharum officinarum), Venezuela 51–71 variety, on the grower’s oasis substrate

Abstract

One hundred samples of rhizosphere taken from 16 crop lands located in the Tolima, Cundinamarca, and Casanare departments were assessed to isolate solubilizing bacteria (PSB) populations. PSB constituted 20% of the total isolated population. Two isolates identified as Xanthomonas maltophilia and Enterobacter cloacae, were selected for their ability to form solubilization halos within a Pikovskaya medium with Ca3(PO4)2. In a greenhouse assay, buds of sugar cane, variety Venezuela 51--71, were planted and fertilized with Fosforita Huila, in the Grower's Oasis rooting medium. Then, an inoculation with the two selected microorganisms was performed on treatments that showed no significant differences in phosphate uptake at 90 days, as compared with the control. However, there were significant differences in plant growth, as the stem length under the phosphate treatment and the mixture of the two bacteria was of 32 cm, while such length was of 17 cm under the positive control. Similarly, stem length with the phosphate treatment and E. cloacae was of 9 cm, as compared with 5 cm with the positive control. As for root growth, an increase of 2.57 times was observed, as related to the positive control's dry weight. Root length was increased 0.73 times, being similar to that of the KNO3 control.