WANG Tao, WANG Zhan-Li, LI Shu-Na, GUO Xiao-Jun, ZHU Bao-Cheng
Cotton Science. 2010, 22(2): 169-174.
The ideal antagonistic strain requires not only high antagonistic activity, but also for the colonization capability with hosting in plant roots and rhizosphere soil. Antagonistic bacterium DS45-2 has inhibitory activity against Verticillium dahliae and high potential biological control value. Colonization of biocontrol strain DS45-2 in soil, rhizoplane and endophytic of cotton were studied against V. dahliae in a growth chamber. In this paper, we considered control, seed dressing, all soil bacteria, some soil bacteria, inoculating of pouring as treatments, and the colonization characteristics in natural soil and sterilized soil were analyzed. The results showed that antagonistic strain DS45-2 can colonize with strong antagonism activity against V. dahliae in soil and the root of cotton. When applied to the seed of cotton and inoculated in soil, the population of strain DS45-2 balanced gradually, and the numbers maintained about 106 cfu·g-1 in the soil. After 45 days, the population was 2.35×104 cfu·g-1 in the endophytic of cotton, and was 97.4×106cfu·g-1 in the rhizoplane of cotton. The numbers in the natural soil were less than those in the sterilized soil, the trends are identical in both varieties, as a result of weak nutrition and space resources competition in the sterilized soil with a single microorganism. With the increasing of depth of the soil the population of strain DS45-2 declined, but was not obvious. Which indicated that the deeper soil factors, including the dense structure, poor ventilation, larger humidity, relative poor nutrition, and so on, had affected the colonization capability of biocontrol strain DS45-2. According to this experiment, it is suggested that the colonization capability of biocontrol strain related to their own genetic characteristics, the ability to use root secretions and the soil environment.
