The potentials of phytochemical amendments in soil to suppress the foliar fungal disease by priming are yet to be explored. This study explores the putative role of priming in Chinese cabbage, Brassica rapa L., by soil amendments using Turmeric (Curcuma longa L.) rhizome extract on the fungal pathogen, Colletotrichum species causing Anthracnose disease. Two experiments were conducted. In the first experiment, two sets of plants were prepared in pots and in one set, the pot soil was amended by adding predetermined doses of turmeric extracts, twice a day, for three days and the second set was without any amendments. Both treatments were inoculated with Colletotrichum sp. conidia suspension. The plants were examined after seven days for the number of foliar lesions and quantified. In the second experiment, the growth of Colletotrichum sp. was studied in Potato Dextrose Agar (PDA) culture plates in a) plates amended with turmeric rhizome extract and b) those amended with commercial fungicide and c) non amended plates as control to understand the fungicidal property of turmeric. Results of the first experiment showed a statistically significant reduction (P< 0.0001) on the number of foliar lesions among plants grown in amended soil when compared with plants grown in non-amended soil. In the second experiment, the mean radial growth of Colletotrichum sp. increased significantly (P < 0.05) after 96 hours in the control and turmeric rhizome extract amended PDA plates compared to the amended plates with fungicide. The study reveals that although the turmeric rhizome extract does not have any fungicidal property against the Colletotrichum, it can induce priming to develop disease resistance in plants.
Fourth Award of $500