Abstract

RODRIGUEZ-GAVIRIA, Paola Andrea  and  CAYON, Gerardo. Physiological effect of Mycosphaerella fijiensis in banana leaves. Agron. colomb. [online]. 2008, vol.26, n.2, pp.256-265. ISSN 0120-9965.

Rates of photosynthesis and transpiration, and chlorophyll, sucrose, starch and reducing sugar contents were quantified in banana leaves with and without black sigatoka, a disease caused by the fungus Mycosphaerella fijiensis Moleret. The disease affected all physiological variables. Biomass and photosynthetic pigments were affected from the earliest infection stages and this effect was related to photosynthesis and transpiration process. These two processes, as well as resistance and stomata activity, were more affected as disease severity increased. Fungal penetration and release of conidia caused severe damage in the stomata structures. Decreases in starch and sugar concentrations occurred from the onset of infections and were presumably related to the consumption of these compounds by the fungus during penetration. All the measured variables are related to basic physiological processes indicating severe damages in banana leaf tissues that affect plant function, growth and production. Irreversible cell damages are caused at the earliest disease stages, however, the most severe effects are observed at the fourth stage. These results suggest the necessity of an early disease control for a good crop management.

Keywords : plant diseases; black sigatoka; photosynthesis; transpiration; plant-pathogen; interaction.

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