混配制剂中拮抗细菌菌株Pf7-14在稻株上的群体数量及其对水稻纹枯病的防治

Population Sizes on Rice Plants of Antagonistic Bacterial Strain Pf7-14 in the Mixture and the Efficacy of the Mixture against Rice Sheath Blight

菌株Pseudomonas fluoresecens 7—14（Pf7—14）显著地抑制了水稻纹枯病。在温室条件下，在水稻（品种为IR72）健株和纹枯病菌（Rhizoctoniasolani）接种的病株上于分蘖盛期分别喷雾Pf7—14、混剂（Pf7-14＋井冈霉素），菌株Pf-14对用于标记的抗生素萘啶酮酸（Nalidixic acid）具有天然的抗性，以上两处理中Pf7—14的浓度相同，约为2．2×10^8cfu／mL，应用稀释平板法，在喷雾后的不同时期，在含萘啶酮酸100μg／mL的培养基上回收Pf7-14。结果表明：无论是在健株还是在病株上。在两批试验中，混剂中Pf7—14的种群数量总是高于其在单剂的数量，在健株上，应用1—4d，两者显著性相差1．69—2．96倍（P=0．05）。在病株上，第4～7d，两者显著性相差1．74—3．70倍。田间试验结果表明，无论是一次防治，还是两次防治，与两个单剂相比，混剂（Pf7-14＋井冈霉素）对水稻纹枯病的防治效果得到显著性提高。两次防治中，混剂的防治效果为83．46％，而单剂Pf7—14和井冈霉素的防治效果分别为56．92％和73．72％。

Antagonistic bacterial strain ,Pseudomonas fluorescens Pf7 - 14, the potential biocontrol agents, suppressed rice sheath blight significantly. The population sizes of Pf7- 14 （ natural nalidixic acid - resistant strain） were monitored under green house conditions by spraying bacterial suspensions of Pf7 - 14, mixture （Pf7 -14 ＋ Jinggangmycin） at the full tillering stage,periodical sampling,and recovering the bacteria through diluting -plate method. The results showed that the population sizes of Pf7 - 14 in the mixture were higher than those individual. On healthy rice plants, the population sizes of PH - 14 in the mixture were 1.69 - 1.96 times significantly higher than that of Pf7-14 only,on the diseased plants,those in the mixture were 1.74 -3.7 times significantly higher than those of Pf7 - 14 only over the two trials. The field experiment revealed that the efficacy of the mixture against rice sheath blight was higher than that of any of the singles, spraying either once or twice. For example, the efficacies of the mixture, Pf7 - 14 and Jingangmycin were 83.45%, 56.92% and 73.72% respectively.