[Factors affecting colonization of introduced microorganisms on plant roots]

Microorganisms such as biological control agents (BCA), plant growth-promoting rhizobacteria (PGPR) and yield increasing bacteria (YIB) were introduced along growing roots. The colonization process of introduced bacteria was proved that they attached root tipfirst, then distributed along roots, multiplicated there, and survived as certain population size. The colonization location was closely related with root exudates, which was usually at the junction between cortex cells or at the base of lateral roots or root hairs. The variation of colonization by introduced microorganisms in the rhizosphere was caused by biotic and abiotic factors. Biotic factors included the physiological characters of introduced microorganisms and interactions between introduced microorganisms and native microbes. The more important factors were plant genotypes which associated with introduced beneficial microbes and regulated the population and community of those microbes affecting the colonization of introduced microorganisms. Abiotic factors here referred to soil environmental conditions, e.g., soil texture, water content, soil temperature and pH value.