Abstract:

Endogenous Enterobacter species were isolated from Paspalum vaginatum and were then used to study the influence of plant endophytic bacteria on the salt tolerance of bermudagrass in two methods of seed germination and pot experiment. In pot experiments germinating bermudagrass seeds and seedlings forming miniature turves in pots 10 cm×10 cm×9 cm were inoculated with a single species of endophytic bacterium （Enterobacter ludwigii） or with a mixture of two endophytic bacterial species （E. ludwigii+Enterobacter bugandensis）. The experiments also included blank controls （CK）. Seed germination rate， shoot length， root length and biomass growth indexes， chlorophyll content， relative water content， relative electrical conductivity and leaf contents of sodium and potassium ions were determined to provide a comprehensive evaluation of effects of endophytic bacteria on bermudagrass salt tolerance. It was found that when germinating bermudagrass seeds under 150 mmol·L^-1 NaCl stress were assessed after 14 days， germination， radicle length and plumule length each ranked B3014>B30>CK （P<0.05）. For potted plants subjected to 200 mmol·L^-1 NaCl stress that had formed turves， inoculation with endophytic bacteria enhanced turf quality， shoot length， root growth， shoot and root biomass， chlorophyll content and relative water content of leaves， and also reduced cell membrane electrolyte leakage and these effects were more pronounced for B3014 than for B30 （P<0.05）. In addition the endophytic bacteria facilitated reduction of Na⁺ and increase in K⁺ concentrations in tissues of inoculated plants， with these effects again more pronounced in the B3014 treatment than in the B30 treatment. In summary， inoculation with Enterobacter improved seed germination and salt tolerance of bermudagrass seedlings under salt stress， and B3014 was more effective than B30 alone. Enhancement of the salt tolerance of bermudagrass by inoculation with endophytic bacteria provides a new method for improving the performance of turfgrass in saline alkali environments.

Key words: endophytic bacteria, bermudagrass, seed germination, salt tolerance