Effect of Some Agronomic Practices on Ascochyta Blight Severity and Yield of Faba Bean (Vicia faba L.) in Tunisia

Abstract

Background: In Tunisia, faba bean (Vicia faba L.) is the first major food legume. The development of faba bean production is facing several biotic constraints. Faba bean Ascochyta blight caused by Ascochyta fabae is one of the most destructive diseases of faba bean and can cause significant yield loss under favorable conditions. As only incomplete resistance ABL varieties are available, some agronomic practices should be applied to control and reduce Ascochyta blight incidence wherever possible. Therefore, this work was undertaken to evaluate the effect of spacing row and seed rate on ABL severity, growth and yield of faba bean. Methods: A split-plot design with three replications was adopted to carry out this study during 2018 and 2019 cropping seasons. ‘Bachaar’ faba bean variety was sown at 40 and 60 cm row spacing and at three seed rates (100, 140 and 200 kg ha-1). ABL severity was assessed visually on a 0-9 scale and agro-morphological traits were measured. Analysis of variance was used to analyze the data. Correlations between agronomic traits, row spacing, seed rate and ABL severity were investigated. Result: Results showed that seed rate has a larger effect on yield than row spacing. In both cropping seasons, the highest grain yield was recorded in 60 cm row spacing and 140 kg ha-1 seed rate treatment. So, this treatment is recommended for obtaining high yield of faba bean. Most of the variation in disease severity was associated with seed rate (r=0.62). The highest ABL score severity was noted at 200 kg ha-1 rate. Over both years, wide row spacing and low seed rate reduced ABL severity. In this study, the small amounts of ABL disease (which reached a score of 5.3 and 4.7 in 2018 and 2019, respectively) had little or no effect on yield.