Effects of pesticides on mycorrhizal symbiosis in tea

Abstract

The experiment was conducted at BTRI farm to evaluate the effect of pesticides on mycorrhizal symbiosis in tea. Different pesticides were used along with mycorrhizal fungi. In the results, variable effects of pesticides on the symbiosis were observed. The systemic fungicide Calixin @ 1.12 L ha-1 (T8) significantly (P=0.01) suppressed the mycorrhizal activities in tea. 33% mycorrhizal colonization in roots and 54% spore populations in rhizosphere soil were reduced by application of Calixin. From the results, it can also be seen that Calixin significantly (P=0.01 decreased the total plant height (2.9%), iresh weight (4.6%), dry mass (16.4%) and number of leaves (4.8%) of tea saplings, compared to without Calixin application (T2). The adverse effect on AM fungal activities was also recorded by using systemic herbicide Roundup (T14). No harmful effects were observed in the treatment of fimgicides Knowin and Macuprax; herbicides Gramoxone and Bimastar on the symbiosis in tea. The application of Knowin, Macuprax, Gramoxone and Bimastar along with AM fungi significantly (P=0.01) increased plant height, fresh and dry mass, number of leaves, percentage root colonization of mycorrhizal fimgi and spore population in rhizosphere soil. The insecticides Fentox, Thiodan and Carbofuran had also no harmful effect on mycorrhizal symbiosis in tea.