利用拮抗细菌防治棉花黄萎病

本项目研究中，从植物根围、根表和植物内部分离到1345株细菌，并测定了他们对棉花黄萎病菌的抑菌性。118株细菌表现较强的抑菌性，抑菌率≥50％。其中25个菌株的抑菌率≥。70％，93个菌株的抑菌率为50％～70％。另外从棉花黄萎菌的微菌核际分离到57株细菌，其中30株细菌能显著地抑制棉花黄萎菌微菌核的菌落生长(5个菌株完全抑制微菌核的萌发和生长，15菌株的抑菌率为40％～97％)。这些拮抗菌的培养滤液也能抑制棉花黄萎菌的生长。室内盆栽实验证明，应用拮抗菌处理棉花种子，有10个拮抗细菌能极显著地防治棉花黄萎病，其中4个菌株(ICB-18、NCD-2、CS-25和CS--27)的防病效果极好，防病效果为72．3％～81．4％，3个菌株(C-94、C-28和NCD-25)的防病效果为55．7％～61．9％。1999～2000年的2年田间小区试验中。NCD-2菌株对棉花黄萎病防治效果显著，并且显著优于国外商品化生防制剂TF，该菌株连续两年的防病效果平均为85．4％；另外4个菌株(ICB-18、CS-25、C-94和C-28)亦能显著防治棉花黄萎病，但防病效果与国外商品化生防制剂TF相当。在田间示范中，应用生防细菌NCD-2制剂拌种后直接播种技术防治棉花黄萎病，防病效果达到51．2％。同时应用生防细菌NCD-2制剂拌种育苗移栽技术防治棉花黄萎病，防病效果达到52．6％并且增产22．85％。本文同时测定了NCD-2对主要大田作物的安全性，证明其对小麦、玉米、棉花、马铃薯、黄瓜、茄子和大豆等7种作物没有致病性，并且对这些作物的出苗、生长和发育没有不良影响。

Biological control of Verticillium wilt of cotton caused by Verticillium dahliae with antagonistic bacteria

In this study,1345 strains of bacteria isolated from rhizosphere,rhizoplane and endophytic tissues of diverse plants grown in China were tested in vitro against Verticillium dahliae.Of these,118 isolates showed strong antagonism,with an inhibiting rate of ≥50%, 25 isolates had an inhibiting rate of ≥70%, and 93 isolates had an inhibiting rate from 50% to 70%.57 bacterial strains were isolated from microsclerotia of V. dahliae and 30 isolates significantly(P=0.01)reduced the colony development of microsclerotia compared to the control. Five of those isolates completely inhibited germination of microsclerotia and another 15 isolates displayed inhibiting rates from 40% to 97%. Filtrates produced from antagonistic bacteria were also inhibitory to growth of V. dahliae.When applied to the seed of cotton in a growth chamber, 10 antagonistic bacterial strains significantly (P=0.01) reduced indices of cotton Verticillium wilt.Disease control efficacies for 4 strains of antagonists (ICB-18, NCD-2, CS-25 and CS-27) ranged from 72.3%-81.4%; and another 3 strains (C-94, C-28 and NCD-25) ranged from 55.7% to 61.9% control. In field trials, Strain NCD-2 significantly (P=0.05) reduced the disease index during 1999-2000 compared to both the untreated control and the commercial biological control product TF (Talaromyces flavus).The average control efficacy for this isolate was 85.4% for these 2 years.The other 4 strains (ICB-18, CS-25, C-94 and C-28) significantly (P=0.05) reduced disease compared to the control, but were not significantly different to TF.In a demonstration trial, Strain NCD-2 reduced the disease index by 51.2% when applied as a seed treatment and following conventional direct planting methods.The disease index was reduced by 52.6% and yield increased by 22.85% when Strain NCD-2 was applied by seed treatment and transplanting.Safety testing showed that Strain NCD-2 had no detrimental effects on seed germination, growth and development of wheat, corn, cotton, potato, cucumber, eggplant and bean in a growth chamber.