RESPONSE OF AFRICAN VIOLET (Saintpaulia ionantha H. Wendl.) TO INOCULATION WITH PLANT GROWTH PROMOTING RHIZOBACTERIA IN NURSERY

Abstract

The African violet (Saintpaulia ionantha H. Wendl.) worldwide is a highly prized ornamental potted plant where demand for it generates high revenues. However, the constant rise in the price of chemical inputs requires finding alternative management strategies where production costs of the crop are kept in line with local and global competitiveness. In this context, the plant growth promoting rhizobacteria (PGPR) are possible candidates due to the synergistic interactions and diverse beneficial effects on their host plants. In this study, we evaluated the effect of Bacillus subtilis 1 and B. subtilis 2 (Bs1 and Bs2) isolated from papaya (Carica papaya) and basil (Ocimum basilicum) in Baja California Sur (Mexico), respectively, on S. ionantha cultivated in nursery under a routine method for the generation of commercial flowering plants. Nine treatments were considered (Fertilization [F]100%, F50%, F75%, Bs1, Bs2, Bs1+F50%, Bs2+F50%, Bs1+F75% and Bs2+F75%), with 50 replications. The following parameters were measured: number of leaves, leaf area, dry weight of leaves, roots and petioles, number of button flowers and the UCF. The data processed with STATISTICA (StatSoft Inc., Tulsa, OK) commercial software showed statistical differences in leaf area with Bs1+75%F (?47.63%) and Bs2+50%F (?37.15%) when the rhizobacterias acted with reduced fertilizer rate, compared to the fertilized plants. The last one (Bs2+50%F [8.91X10⁵ g^-1 rhizosphere soil]) was the treatment with the biggest UCF. These results demonstrate the importance of incorporating PGPR in these systems of production, in order to provide cost savings and decrease the application of inorganic fertilizers.