Gabr, M. A. and M. Nour El-Din( 2012). Evaluation Of Selected Azospirillum Sp. Isolates For Iaa Production And Their Potential Impact On Improving Growth, Yield And Fruit Quality Of 'Anna' Apple TreesJ. Agric. Chem. and Biotechn., Mansoura Univ. Vol. 3 (3): 65 - 75, 2012
Abstract: Foliar spray with the diluted PGPR (plant growth promoting rhizobacteria) cultures had utmost importance due to its content and release of stimulants, nutrients, antibiotics, biocides and siderofores. Potentiality of these microorganisms, in plant rhizosphere, in activation and improving of plant growth as will as increasing plant tolerance to different plant biotic and abiotic stresses have been proved. However, microbial types and even microbial strains varied for their potentiality to adapt, inhabit and release of stimulants and phytochemicals. A number of Azospirillum sp. isolates were isolated from phyllosphere of apple, orange, lemon, mango and guava trees, grown at El-Bostan area, Egypt. These isolates were used in spray of apple trees with the dose of 20 and 40 L/feddan compared to water spray control. Foliar spray of apple trees with all Azospirillum isolates notably induced the plant growth and increased fruit yield, but did not significantly affected fruit quality. However, the used isolates largely varied in their efficiency and potentiality. A3 isolate was the superior followed by A7 which attained the highest increases in shoot length, shoot diameter, leaf area, leaf dry weight leaf content of chlorophyll a, b and total chlorophyll as will as fruit yield over those of control treatment. But, the quality parameters, i. e., SSC (soluble solids content), acidity, firmness and color did not show consistent significant variations. The treatments of spray with Azospirillum isolates attained high increase in net return (L E/fed), the spray with the treatments of A7D (isolated from mango phyllosphere and used with the rate of 40 L/fed.) and A7R, which isolated from mango phyllosphere and used with the rate of 20L / fed.) were the superior treatments which achieved increases in net return over that of control (water spray) by 6120 and 6200 L E/fed respectively, followed by A3R (isolated from phyllosphere of apple and applied with 20 L/fed.) which gave 5595 L E/fed. It is noted that the microbial culture dose of 40 L/fed had no significant differences than the application of 20 L/fed. Therefore, we recommend the spray with an efficient Azospirillum isolate like A3 or A7 with the dose of 20 L/fed, and it is also of importance to condense studies on isolation and evaluation of these microorganisms to select the most efficient strains for use, as inoculants, in spray of apple trees.
Keywords: ()
