盐胁迫下解盐促生细菌Rs-5和Rs-198促进棉花种子发芽的机理探讨

 【目的】研究解盐促生细菌Rs-5和Rs-198的生理特性及其在盐胁迫下对棉花发芽的影响，并进一步探讨两株菌的促生性能。【方法】利用钼锑抗比色法和Salkowski法分别测定细菌培养液中可溶性磷和IAA（吲哚-3-乙酸）的含量，并通过盆栽试验检测两株菌对棉花发芽的影响。【结果】经菌株的生理生化初步鉴定，菌株Rs-5和Rs-198分别归属克雷伯氏菌属（Klebsiella sp.）和假单胞菌属（Pseudomonas sp.）。两株菌处理棉花种子后，种子在含盐土壤中的发芽率分别比对照提高了26.3%和34.4%。在无机磷培养基中菌株Rs-5和Rs-198都具有溶解磷酸三钙的性能，可溶解磷的最大含量分别达到了73.38和82.41 mg•L-1，培养基的pH分别由7.48降到5.22和4.54。在测定IAA的分泌试验中，菌株Rs-5和Rs-198培养液中的IAA含量在96 h分别达到了7.09和10.77 mg•L-1，并一直保持较高水平。【结论】两株菌的产酸溶磷与分泌生长素的性能是在盐胁迫下提高棉花发芽和出苗率的主要原因。

Physiochemical Characters and Ability to Promote Cotton Germinaton of Bacteria Strains Rs-5 and Rs-198 Under Salt Stress

Two plant growth-promoting bacteria, strains Rs-5 and Rs-198, isolated from salt-stressed cotton rhizosphere, could improve germination rate of cottonseed under salt stress. The ability of solubilizing tricalcium phosphate and secreting IAA (indo-3-acetic acid) of strains Rs-5 and Rs-198 were tested.Cotton seeds germination was tested by pot experiment. Spectrophotometrically with Mo-Sb-VC and Salkowski methods were used to determine content of solubilizing tricalcium phosphate and IAA.The two bacteria strains were characterized as Rs-5 Klebsiella.sp and Rs-198 Pseudomonas.sp. The germination rates was 26.3 % and 34.4 % more than control. During seven days fementation, the soluble phosphate contents solubilized by the strains Rs-5, Rs-198 in fementation broth reached to 73.38 mg•L-1 after incubating 24 hours and 82.41 mg•L-1 after 48 hour, respectively. The pH value in fermentation broth of the two strain decreased from 7.48 to 5.22 and 4.54, respectively. Contents of IAA secreted by Rs-5 and Rs-198 in cultures were accumulated following the incubation time. The contents of IAA were accumulated to 7.09 mg•L-1mg•L-1 and 10.77 mg•L-1 each at 96 hours fermentation. Phosphate solubilizing and IAA secretion might be the main reason for promoting cotton germination under salt stress.