Screening On Suitable Leguminous Plants Intercropping In The Tea Plantation

Nitrogen-fixing bacteria are isolated and purified from the roots of four leguminousplants intercropped tea plantation under the condition of nitrogen-free medium,and then theyare classificated screening and identificated.The suitable leguminous plants are selected fortea plantation based the result of nitrogen preference,enzymes activity of nitrogen metabolism.The major development as follows:（1）Using leguminous plants of different periods as materials, their nitrogen preferencewere measured by hydroponics under NH4+-N/NO3--N=1:1, and then, their activities ofNitrate Reductase （NR）and Glutamine Synthetase （GS）activity were determinated indifferent development periods. The results showed that three of leguminous plants have astrong nitrate nitrogen preference. Among them, Medicago sativa cv.KINDER is the strongest,and it also has the highest activity of NR, weakest activity of GS, which is in the leaf and roottogether，lowest ratio of GS/NR and amount of nitrogen absorption. Therefore, it can be themost suitable intercropping plants in the tea garden.（2）By leguminous plants intercropped with fudingdabai adult tea,we observed thegrowth characteristics of the leguminous plants and growth position of nodule.The resultsshowed that absorb district of the four leguminous plants roots are complementary in verticaldistribution with tea, but also can form densely meadow easily. But the KINDER has deeperroot and less branches, it is easy to compete the nutrient with tea. The Vicia sepium Linn. isnot sutitable for intercropping with tea. The four leguminous plants have the same form inposition and colour of nodules, but the shape and weight have siginificant differences.（3）Four nitrogen-fixing bacteria with high nitrogenase activity are screened by cloningthe bacterial nitrogenase gene nifH,clustering analysising bacterial whole-cell protein anddetermining nitrogenase activity,and are identificated with the "Berger bacterial identificationmanual", in the light of its16SrDNA molecule sequencing, the results of physiological andbiochemical characteristics determinatingas well as as the observation of negative stainingelectron microscopy. The results showed that the four nitrogen-fixing bacterium areAgrobacterium viscosum、Comamonas sp、Enterobacteriaceae agglomerans and Klebsiella oxytoca. Among them,Klebsiella oxytoca has highest nitrogenase activity which reaching37.82μmol h-1mL-1,and its suitable temperature is10℃to40℃, pH is4to10.（4）Klebsiella oxytoca with highest nitrogenase activity were screened in Trifoliumrepens cv. PROP/CLARE; Three of nitrogen-fixing bacteria（Agrobacterium viscosum,Comamonas sp, Enterobacteriaceae agglomerans） with high nitrogenase activity werescreened in Medicago sativa cv. KINDER where the most bacteria were screnned. There isonly one bacteria of Agrobacterium viscosum screened in Vicia sepium Linn.. The separatingeffect of screened bacteria about Vicia sepium Linn. is much worse than other plant, it is clearthat two kinds of Trifolium repens and Medicago sativa cv. KINDER have comparativeadvantages in sceening endophytic diazotrophs.