Influence of Plant Growth Regulators and Azospirillum on Rooting of Air Layers in Guava (Psidium guajava L.)

Investigation was carried out on air layering in guava as influenced by growth regulators and Azospirillum was carried out in the Orchard, Department of Horticulture, Faculty of Agriculture, Annamalai University, Annamalainagar during 2013-14 aimed to find out suitable ischolar_main inducing treatment in mature shoot air-layers of guava cv. L-49. There were 14 treatment combinations with three replications laid out in Randomised Block Design. In general, both growth regulators viz., IBA, NAA alone and in combination with Azospirillum favoured ischolar_maining in air-layers. Among the different combinations, the layers which had received Azospirillum 37.5g + IBA (Indole butyric acid) 3000 ppm + NAA (Naphthalene acetic acid) 3000 ppm (T₁₂) recorded significantly higher percentage (91.68%) of ischolar_maining with desirable ischolar_main characters such as higher number of primary and secondary ischolar_mains, longer length of primary ischolar_mains and higher girth of primary ischolar_mains. Next to this treatment, the other favorable treatments were IBA, 3000 ppm + NAA, 3000 ppm (T₆), IBA, 2000 ppm (T₁), Azospirillum37.5g + IBA, 4000 ppm (T₈), Azospirillum37.5 g + IBA, 6000 ppm (T₉), Azospirillum 37.5 g + IBA 2000 ppm + NAA 2000 ppm (T₁₁). The use of medium concentration (3000 ppm) of both the growth regulators (IBA and NAA) with Azospirillum 37.5g was more effective as compared to either lower (2000 ppm) or higher (6000 pm) concentrations of IBA and NAA.