| The studies about wheat and maize good quality and high output high-efficient culture mode in arid and semi-arid region in the northwest of our country are important theory and practice meanings to instructing this area grain-production. The estimate to various kinds of culture mode environmental effect is important scientific value to optimum mode through the change of soil microflora. In this paper, soil microflora and actinomycetes resources in rhizosphere and outrhizosphere of wheat and corn under the different culture modes and different nitrogen in arid and semi-arid region of northwest were studied systematically by normal methods. The results were followed: 1. Study on the soil microflora in the wheatland. The soil microflora in the rhizosphere and outrhizosphere of wheat under the 5 culture modes and 3 pieces of amount of nitrogen were studied by nomal methods. The results indicated that: ①　There were obvious differences in the quantity of bacterium, fungi and actinomyces in rhizosphere and outrhizosphere of wheat under 5 modes of cultivating. The quantity of soil microorganism was relatively high in wheatland under only cover membrane and furrow mode (that is cover membrane and collect water). ②With the increase of nitrogen, the bacterium's quantity had the tendency to reduce, the actinomyces is contrary to it, and the quantity of fungi was relatively high at N0 and N8. ③The quantity of soil bacteria and fungi in rhizosphere were higher than outrhizosphere under 5 kinds of culture modes; besides furrow, actinomycetes quantity in rhizosphere was higher than outrhizosphere at GA culture under other 4 culture modas. ④Besides cover grass, the fungi kinds in rhizosphere was higher than outrhizosphere under other 4 culture modes, and the fungi kinds was the fewest under cover grass. 2. Study on the soil microflora in the cornland. The soil microflora in the rhizosphere and outrhizosphere of corn under the 4 culture modes and 3 pieces of amount of nitrogen were studied by normal methods. The results indicated that: ①There were obvious differences in the quantity of bacterium, fungi and actinomyces in rhizosphere and outrhizosphere of corn under 4 modes of cultivating. It was favorable to the improvement of the quantity of bacterium,fungi and actinomycetes under cover membrance. ②With the increase of nitrogen, the bacterium's quantity in rhizosphere of corn reduced gradually, and the outrhizosphere is contrary to it. The quantity of fungi in outrhizosphere and actinomycete in rhizosphere (on GA) was increased with the increase of nitrogen. The quantity of fungi in rhizosphere and actinomycete in outrhizosphere (on GA) was the highest at N8. ③The quantity of soil fungi and actinomycetes in rhizosphere were higher than outrhizosphere under 4 culture modes; the quantity of soil bacteria in rhizosphere was higher than outrhizosphere under other 3 culture modes expect cover membrance. ④Besides cover grass N0, the fungi kinds in rhizosphere was higher than outrhizosphere under other treaments, and the fungi kinds was the fewest under cover grass. 3.The composing and ecological distribution of actinomycetes. More than 4000strains of actinomycetes in the samples were isolated by spreading the samples on two kinds of culture media. The results indicated that: ①In wheatfield and cornfield, Streptomyces was the main genus, accounted for the total quantity of actinomycetes respectively 82.2%~88.1% and 89.6%~93.8%. And the percentage of Streptomyces in cornfield was higher than wheatland. ②The percentage of Streptomyces in wheatfield was higher under normal way and furrow, and was lower under winter imigate and cover grass; but the percentage of Streptomyces in cornfield was higher under fallow and normal way, and was lower under winter imigate and cover grass. ③The main kind of soil Streptomyces composing (GA) in wheatfield was Griseofuscus, but was Lavendulae in cornfield. The difference of groups of Streptomyces was little in wheatfield and cornfield under different culture modes. ④The quantity and composing of Streptomyces were different on GA and HA culture media in wheatfield and cornfield. The groups of Streptomyces was high on GA, and the percentage of Streptomyces was high on HA. 4. Study on the isolation of antimicrobial actinomycetes. The antimicrobial action 4186 representative strains were measured by methed of agar block. The results indicated that: ①18.5%,6.9%,7.6%,3.0%,4.7%,6.0%,8.6%and11.6% of tested strains had antimicrobial activity against Staphylococcus aureus, Escherichia coil, Penicillium sp., Candida tropicalis, Fusarium oxysporium f.sp. vasinfectum, Fusarium oxysporum f.sp. cucumerinum owen, Fusarium oxysporum f.sp. nieveum, and Phytophthora Capsici, respectively, which illustrated that there had more antimicrobial actinomycetes against bacteria than fungi, more antimicrobial actinomycetes against G+ bacteria than G-bacteria, more antimicrobial actinomycetes against fila fungi than unicellular fungi, more antimicrobial actinomycetes against Phytophthora Capsici than other 3 kinds of pathogenic fungi. ②There were 768 strains of antimicrobial actinomycetes in wheatfield, its percentage was 34.5%; and there were 573 strains of antimicrobial actinomycetes in cornfield, its percentage was 29.2%. ③The percentage of antimicrobial actinomycetes from rhizosphere and outrhizosphere of wheat is 34.5%; The percentage of antimicrobial actinomycetes from rhizosphere and outrhizosphere of corn are 29.2% and 29.3%, respectively. ④Among the 5 ways of cultivation, the quantity of antimicrobial actinomycetes was 30.0%~38.5% of the total actinomycetes quantity that be retained from the relevant patterns, and the furrow pattern was best; mostly, the percentage of antimicrobial actinomycetes in the HA was more than it in the GA; The percentage of antimicrobial actinomycetes fromrhizosphere are more than them from outrhizosphere except the covering grass pattern. ⑤Under 4 kinds of culture modes of corn and fallow, the percentage of antimicrobial actinomycetes of the total actinomycetes quantity that be retained from the relevant patterns was 23.2%~73.2%,and routine mode was far higher than other modes. Besides winter irrigate mode, the percentage of antimicrobial actinomycetes from rhizosphere was higher than from outrhizosphere under other culture modes. ⑥Correlated coefficient between soil organic matter and the total quantity of actinomycetes, and the quantity of actinomycetes tested and antimicrobial actinomycetes got to very remarkable level respectively (P<0.01) or remarkable level (P<0.05). ⑦The quantity of antimicrobial actinomycetes from rhizosphere and outrhizosphere of wheat and corn was more that had strong antimicrobial activity against target bacteria, and the quantity was more that had middling antimicrobial activity against target fungi. ⑧With the increase of target microbe tested, the quantity of antimicrobial actinomycetes reduced gradually; The quantity of antimicrobial actinomycetes against 8 and 7 kinds of target microbe were 18 strains and 34 strains respectively. There were 13 strains from wheat soil samples and 39 strains from corn soil samples, and 33 strains from rhizosphere and 17 strains from outrhizosphere among 52 strains broad-spectrum antimicrobial actinomycetes. 5. 52 strains of broad-spectrum antimicrobial actinomycetes identify preliminarily. According to morphological and culture characteristics, 52 strains of antimicrobial actinomycetes isolated from soil tested was identified. The results indicated that: 51 strains of 52 strains of antimicrobial actinomycetes were Streptomyces and only 1 strains was Micromonospora. 17strains of 51 strains of broad-spectrum antimicrobial Streptomyces were Lavendulae.
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