PLANT GROWTH PROMOTING MICROORGANISMS AND BIO-CONTROL OF PYTHIUM ULTIMUM ON EUPHORBIA PULCHERIMA

The aim of the present study was to evaluate the effect of 4 microorganisms on: 1) the vegetative growth (PGP) and 2) the bio-control of the pathogenic fungus Pythium ultimum on Euphorbia pulcherima ‘Mars Improved’.
Plant growth promoting assay: plants were inoculated with the microorganisms at planting and the vegetative development of plants was compared to a non-inoculated control. The vegetative growth was evaluated by measuring the stem length, the stem diameter, the total area of all the red-colored bracts, the fresh weight, the dried weight, root fresh weight and root dried weight.
Plants inoculated with Clonostachys rosea f. catenulate (J1446) and G. intraradices showed the most important PGP effect. The inoculation of Clonostachys rosea f. catenulata (J1446) allowed obtaining plants with longest stems and higher values of fresh weight than control plants. The inoculation of G. intraradices allowed obtaining plants with higher values of root fresh weight, root dried weight and stem diameter.
Bio-control assay: plants were infested with P. ultimum two weeks after inoculation of the bio-control microorganisms. The same parameters as described before were measured. The microorganisms inoculated were Clonostachys rosea f. catenulate (J1446), Trichoderma harzianum (T-22), Glomus intraradices, Pseudomonas fluorescens (P_f 153) and Bacillus amyloliquefaciens.
Plants infested with P. ultimum: The inoculation of microorganisms showed positive effect of Clonostachys rosea f. catenulate (J1446) and G. intraradices on vegetative development compared to control plants. As described in PGP results, G. intraradices and Clonostachys rosea f. catenulate (J1446) were the most efficient microorganisms.