Effet <i>in vitro<i> de différents niveaux NPK sur la croissance mycélienne et la sporulation de cinq pathogènes foliaires du riz : <i>Helminthosporium</i> sp. et <i>Curvularia lunata</i>

Abstract

Effet in vitro de différent niveaux NPK sur la croissance mycélienne et la sporulation de pathogènes foliaires du riz: Helminthosporium sp. et Curvularia lunata Helminthosporium oryzae, H. sativum, H. australiensis, H. spiciferum et Curvularia lunata, including the mycelial growth and sporulation. Methodology and Results: Three organic media cultures (PDA, rice meal and malt extract) were used to test the NPK effect on mycelia growth and sporulation of the five fungal species. The sources of nitrogen, phosphorus and potassium were incorporated separately in the culture medium at increasing concentrations, 0.01M (C1), 0.025 M (C2), 0.05M (C3), 0.1M (C4) and 0.15 M (C5), before the sterilization. Two scoring criteria were considered: mycelial growth and sporulation of the fungal species. The obtained results showed that the tested Curvularia lunata and Helminthosporium spp. have variable behaviors, mycelia growth and sporulation on nutritional diets on nitrogen, phosphorus and potassium. These behaviors depend on culture medium, the dose and source of fertilizing element incorporated. Conclusion and results application. This in vitro study on the growth and sporulation has shown a great adaptation of rice foliar pathogens (Helminthosporium spp. and C. lunata) at different levels of the tested NPK. Such adaptation suggests that the nutrient intake has a greater effect on the host as in the pathogen itself. These observations will be useful to approach the in vivo effect of fertilization on rice foliar diseases.