Improved Production of High-Quality Potato Seeds in Aeroponics with Plant-Growth-Promoting Rhizobacteria

We investigated the effect of inoculation with the plant-growth-promoting rhizobacterium Azospirillum brasilense Sp245 under aeroponic conditions on the quality and performance of minitubers of potato (Solanum tuberosum L. cvs. Nevsky and Kondor). In vitro-grown microplants were planted in an aeroponic system, and after 3 weeks of growth, the bacteria were added to the potato nutrient solution. We evaluated the effect of inoculation on the potato growth variables, minituber yield and minituber starch content. Root-associated bacteria were detected by confocal microscopy, and their numbers in the plant growth medium were monitored by enzyme-linked immunosorbent assay. Cells of A. brasilense Sp245 remained on roots during plant growth and were eliminated from the nutrient solution in the aeroponic system within a week after inoculation. Inoculation brought about statistically significant increases in shoot height (16%) and in leaf blade number (14%). The number of minitubers increased by 40% in Kondor plants and by 60% in Nevsky plants, and their yield per square metre increased by an average of 17% in both cultivars. Inoculation also increased the size of starch grains in the amyloplastids (by 12%) and the starch content of minitubers (by 1.5 times). The plant-bacterial association developed in this study was active under aeroponic conditions. This report is the first to show that A. brasilense Sp245 promotes the growth, development and performance of potato and helps to increase the quality of minitubers, thereby contributing to the efficacy of potato seed tuber production.