Abstract:

【Objective】 The purpose of this study is to elucidate the mechanism of root rot resistance in grafted pepper (Capsicum annuum L.), and offer a theoretical basis for regulating root environment and alleviating root rot damage. 【Method】 Changes of disease incidence and disease index of root rot in rootstock (‘Weishi’), grafted (‘Xinfeng 2’ scion grafted onto ‘Weishi’) and own-root plants (‘Xinfeng 2’, control) of pepper, root absorption area, root respiration intensity, population of microoganism and enzymes’ activity in rhizosphere soil were investigated by manual inoculation. 【Result】 The results showed that the root absorption area, actinomyces population and ratio, activities of dehydrogenase, peroxidase and catalase in rhizosphere soil of rootstock and grafted peppers increased significantly compared with those of control before inoculation. After been inoculated, grafted plants showed remarkable lower disease incidence and disease index than control plants, but higher than rootstock plants. Rootstock and grafted peppers had significant higher root absorption area and active absorption area, quantities of bacterium, fungus and actinomyces, actinomyces ratio, and soil enzymes’ activity, in comparison with control. The root respiration rate was lower in rootstock and grafted plants than in control plants at earlier stage, but just the opposite at later stage. 【Conclusion】 The observed increase in root absorption area, quantity of microoganism, ratio of actinomyces, and enzymes’ activity in rhizosphere soil of grafted peppers are important reasons of enhancement of root rot resistance.

Key words: graft, root rot, microorganism, soil enzyme, pepper (Capsicum annuum L.)