大豆根际促生菌的分离筛选及其对大豆和百脉根生长与品质的影响

从贵州毕节地区大豆根际土壤中分离溶磷菌株,从大豆根瘤中分离根瘤菌株。对分离出的溶磷圈直径与菌落直径的比值(D/d值)在2.20以上的溶磷菌株分别进行溶磷能力、生长素(IAA)及有机酸分泌能力、产酸产碱性能测定,筛选出优良溶磷菌4株;对分离出的根瘤菌通过大豆试管苗回接及促生效应试验,筛选出高效根瘤菌2株。将筛选出的6株菌经拮抗反应试验后分别按单一溶磷菌接种剂、单一根瘤菌接种剂、溶磷菌+根瘤菌复合接种剂3种处理制备菌悬液,采用盆栽方法分别对大豆和百脉根进行促生效应试验。结果表明,与对照相比,除单一根瘤接种剂对增加大豆株高无效果外,另外2个处理对大豆株高有提升效果,所有处理对大豆茎粗、生物量、结荚数、荚重、单粒数及单粒重都有明显的促进作用。其中溶磷菌+根瘤菌复合菌液对大豆株高、茎粗、幼苗地上生物量和地下生物量的促进效果最好,分别比对照高出21.26%,40.79%,15.88%和42.19%。3个处理对百脉根的第一、二茬株高及地上生物量、全氮、全磷和粗蛋白含量均有明显的提升效应,其中依然是溶磷菌+根瘤菌复合菌液的处理效果最好,分别比对照高出20.82%,54.88%,106.14%,148.78%,19.34%,61.88%和19.34%,与对照差异均达极显著水平(P0.01)。说明所筛选的菌株组合能产生良好的促生互作效应。

Identification of soybean growth-promoting rhizobacteria and their effects on the growth and quality of Glycine max and Lotus corniculatus

In order to screen combinations of rhizobacteria which have growth-promoting and quality-improving effects on local leguminous crops,phosphorus-solubilizing bacteria were isolated from soybean rhizospheric soils in the Bijie Region of Guizhou Province and rhizobium strains were isolated from soybean root nodules. Phosphorus-solubilizing strains with ratios of the diameter of the phosphorus-solubilizing halo to colony diame-ter of more than 2.20 were tested for their abilities of phosphorus-solubilizing,3-indoleacetic acid (IAA)-secre-ting,organic acid and alkali production.Four superior phosphate-solubilizing strains were selected.For the i-solated rhizobium strains,two highly efficient strains were screened out by means of back-inoculation and growth-promoting effect tests on soybean tube seedlings.The six selected strains were tested for antagonistic reactions and three types of bacterial suspension were prepared:phosphate dissolving only,rhizobia only and a mix of the two.These were immediately inoculated into Glycine max and Lotus corniculatus in pots to test their growth-promoting effects.The results showed that,compared to control,the rhizobia only inoculants had no effect on the plant height of G.max whereas the other two treatments could significantly increase height. All three treatments had significant promoting effects on G.max stem diameter,biomass,number of bean pods,weight of pods,seeds per pod and single seed weight.Among the three treatments,the mix of phos-phate dissolving and rhizobia inoculants showed the best growth effects on soybean seedling plant height,stem diameter,aboveground biomass and underground biomass (respectively 21.26%,40.79%,15.88% and 42.19% higher than control).With regard to L.corniculatus ,all three treatments could improve first and sec-ond harvest plant height,aboveground biomass,total nitrogen content,total phosphorus content and crude protein content.Again,the effects of the mixed treatment of phosphate dissolving with rhizobia inoculants were the highest (respectively 20.82%,54.88%,106.14%,148.78%,19.34%,61.88% and 19.34% higher than control).The results thus indicate that combining phosphate-solubilizing with rhizobium bacteria strains produces a favourable interaction effect.