PLANT GROWTH-PROMOTING RHIZOBACTERIA (PGPR) AS A BIOSTIMULANT TO ENHANCE ECHEVERIA SEEDLING QUALITY AND OFFSET YIELD

ABSTRACT. Echeveria, a genus within the Crassulaceae family, is a highly valued ornamental succulent known for its resilience, vibrant coloration, and attractive rosette morphology. In vegetative propagation of Echeveria, ensuring high-quality root development and increasing offset production are critical for commercial success. Plant Growth-Promoting Rhizobacteria (PGPR), known to synthesize auxins that stimulate root formation, have emerged as promising biostimulants in ornamental plant production. In this study, the effects of three different rhizobacterial formulations -Bacillus pumilus (with three identified active gene regions), Stenotrophomonas spp. (with five identified active gene regions), and a 1:1 mixture of both- were evaluated on seedling quality and offset yield in Echeveria. These formulations were applied through three methods: soil drench, foliar spray, and combined soil + foliar treatment. The results demonstrated that PGPR applications increased offset production by up to fourfold, while significantly enhancing vegetative growth and root development, achieving nearly twice the performance of the control plants. Additionally, protein isolation from leaves revealed notable differences in protein profiles associated with PGPR treatments. Overall, this study highlights the substantial positive effects of different PGPR species on rooting, seedling quality, and protein expression in ornamental succulents. The findings reinforce the growing recognition that rhizobacteria can play a transformative role in advancing more sustainable and environmentally friendly horticultural practices. Keywords: Echeveria, biostimulants, rhizobacteria