CONTRIBUTION OF ARBUSCULAR MYCORRHIZAS TO BIOLOGICAL PROTECTION OF MICROPROPAGATED PINEAPPLE NANANAS-COMOSUS (L) MERR) AGAINST PHYTOPHTHORA-CINNAMOMI RANDS

Phytophthora cinnamomi Rands causes root rot of pineapple (Ananas comosus (L.) Merr.) and the development of this disease is harmful for fruit production. Micropropagated plants of two varieties, Queen Tahiti and Smooth Cayenne (clone CY0), were inoculated at transplanting from axenic conditions with an arbuscular mycorhizal fungus to evaluate the importance of endomycorrhiza development for biological protection against P. cinnamomi. Growth and mineral nutrition of endomycorrhizal plants were not affected by different inoculum levels of P. cinnamomi, whilst they were reduced for non-mycorrhizal plants. Root/shoot ratio of endomycorrhizal plants was lower than that of non-mycorrhizal plants, and the pathogen did not modify this effect except at highest inoculum levels of P. cinnamomi. Endomycorrhizal colonization was not altered by the pathogen; however symbiotic functioning was reduced by the highest concentration of inoculum of P. cinnamomi. Endomycorrhization is an interesting biotechnology for the production of micropropagated pineapple.