Isolation and identification of nitrogen-fixing rhizospheric bacteria from Narcissus flower

Narcissus flower is one of the economic agricultural products of Behbahan in Khouzestan province that is marketed as a cut flower and also as a valuable source for essential oil production. Hence this increasing the yield of this flower is of significant economic importance. Using plant growth promoting bacteria is a suitable approach for this purpose. Nitrogen fixation is one of the mechanisms that is used by these bacteria and promote the growth of the plant. Nitrogen is a growth limiting nutrient for plant growth and yield and in contrast to this fact that it is one of the most elements in soil, only a small fraction of it is available for plant growth. The aim of this study was to isolation and identification of nitrogen-fixing bacteria from the rhizosphere of Narcissus. In order to isolate rhizospheric bacteria, 13 soil samples were collected from the root of Narcissus flower in Behbahan city. 10 g of soil was dispersed in 90 ml of physiological saline and stirred for one hour. The supernatant was then cultured on nutrient agar medium and incubated at 30 °C for 48 h. The isolates were screened for nitrogen fixation according to Dobereiner method and identified based on the enzymatic and biochemical analysis. Separated bacteria were cultured on a Dobereiner medium to determine nitrogen fixation capability. As a result, from 37 bacterial isolates, 28 isolates have nitrogen fixation capability that belongs to the genus Bacillus and Pseudomonas. The use of nitrogen fixation bacteria isolated from the rhizosphere of Narcissus flower can improve nitrogen uptake and subsequently increase plant growth and yield. These isolates can also be a good alternative to chemical fertilizers.

Keywords:

Nitrogen fixation , Rhizosphere , Narcissus flower