Effects of potential N-fixing and IAA synthesis of endophytic bacteria on growth of Vanda plantlets in aseptic condition

Abstract

Orchid tissue culture is a popular technique for orchid production. This method frequently makes use of plant growth regulators such as auxin, gibberellin, and so on. Therefore, this research was aimed to explore around 3 isolates of endophytic bacteria that were isolated from Vanda orchid CV. Manuvadee. These isolates had the ability to fix nitrogen and produce auxin. This research was conducted factorial in a completely randomized design that consists 2 factors such as 1) isolate of endophytic bacteria including isolate 2R13, 3S19, and 3R14 2) ratio of bacteria suspension: sterilize deionize water had 4 levels including 1:1, 1:10, 1:25, 1:50 and control treatment with sterilize deionize water (not contaminate endophytic bacteria).This research had three replications per treatment, and each replication had three plants. Vanda plantlets from tissue culture were immersed in bacteria suspension each ratio including control treatment for 30 minutes and were transferred in Vacin & Went media for 4 months. The results of interaction between factors showed isolate 3S19 at a ratio of 1:25 had the highest average plant height at 10.2 cm. but there was not significantly difference between control treatment. The number of leaves, isolate 3S19 at a ratio of 1:25 and 1:50 had the highest average leaves number per plant of plantlets at 7.7 and 7.1, respectively, compared with other treatments. Furthermore, fresh and dry weights of plantlets were inoculated by bacterial suspension of isolate 3S19 at a ratio of 1:25 had the highest at 1.93 and 0.28 g/plant, respectively. Vanda plantlets morphology were inoculated by bacterial suspension of isolate 3S19 at a ratio of 1:25 that had less morphology disorder than other treatments. Therefore, this research concludes that isolate 3S19 bacteria at a ratio of 1:25 was the optimum treatment for the growth promoting of Vanda under aseptic conditions and