Influência da severidade de mancha angular na eficiência fotossintética da área foliar sadia de feijoeiro, sob condições de campo

Abstract

This paper aimed to show the relationship among healthy leaf area, angular leaf spot severity and bean yield, under field conditions, indicating the influence of this relationship on photosynthetic efficiency of leaf tissue remaining on plants. Leaf area and severity of angular leaf spot [Phaeoisariopsis griseola (Sacc.) Ferraris] of bean were weekly assessed, beginning at 30 days after emergence (DAE). Different levels of severity were reached varying the timing of fungicide spraying (fentin hydroxide 0.10% + tebuconazole 0.04%). Variations on total leaf area were consequence of natural variation on plants and also due to different physic and chemical soil conditions among plots. The relation between healthy leaf area duration (HAD) and area under disease progress curve (AUDPC) and yield (g m-2) presented R2=74.8% and healthy area absorption (HAA), AUDPC and yield (g m-2) presented R2=74.7%. Results indicated reduction of yield when severity (AUDPC) was high, even in plots with same level of healthy leaf area. So, the disease influenced the photosynthetic efficiency of healthy leaf area, besides avoiding the production of the necrotic tissue.