Effect of PGPR Bacterial Inoculum and Amino Acids on the Growth and Oil Quality in Three Varieties of Shrub Rose Rosa Damascene

The experiment was conducted in the winter season of 2023, to evaluate the effect of bacterial inoculum with three types of growth-promoting bacteria PGPR (Bacillus subtilis, Pseudomonas fluorescens, Azotobacter chroococcum) and spraying with commercial amino acids (0, 1.5, 3, or 4.5 g/L) on plant growth and quality indicators of the resulting oil in three varieties of Rosa damascena (red, pink and white). The experiment was split into three parts, and units were distributed as a randomized complete block design (RCBD) of three replications and 576 total experimental units. Experiment measurements were the plant's height, number of leaves, flowers per plant, and petals per flower. The plant's productivity was also estimated based on the flower content of oil. Findings showed that the pink variety was the most vigor with the largest number of leaves. All the PGPR bacteria did not differ in several leaves, but the P. fluorescens treatment resulted in the highest plant height. However, amino acid treatments had a negative effect on plant height compared to the untreated ones. The best results of plant height and number of leaves were obtained from the interaction treatment of the pink or red variety treated with 1.5 or 3 mg L-1 amino acids in the presence of B. subtilis. The most flowers and leaves indicators were on the pink and red varieties that interacted with B. subtilis and P. fluorescens as biofertilization. Increasing the amino acid level to 4.5 mg L-1 resulted in the highest number of rose flowers, but not the number of petals per flower. The pink variety had more oil and a higher oil content, 546.2% and a specific gravity of 18.98 g when interacted with P. fluorescens and 1.5 mg L-1 of amino acid, which did not differ much from the red variety in the same interaction.