Effects of late blight, early blight, and powdery scab on physiological and yield-related traits of potato genotypes

This study evaluated the effects of late blight, early blight, and powdery scab on potato physiology, quality, yield, and integrated disease management effectiveness. Under control conditions, LA was highest in Colomba (91.8 cm2) and lowest in Captiva (79.5 cm2). Among disease-infected variants, Captiva showed the greatest reduction in LA (late blight - 29.2 cm2), whereas Colomba maintained the highest LA (powdery scab - 44.3 cm2). RWC during the mass flowering phase ranged from 93.7% (Amiri-600) to 96.4% (Colomba) under control conditions. Under disease conditions, RWC was highest in Sevinj (76.8%) and lowest in Captiva (49.1%). Sevinj also recorded the highest dry biomass under control conditions at both the budding (69.3 g) and mass flowering (94.1 g) stages. The integrated control scheme applied to Colomba was effective, reducing late blight incidence to 9.6% (87.4% biological efficiency), early blight to 6.5% (87.7%), and powdery scab to 0% (100%). Productivity reached 36.1 t/ha, with profitability of 411.5%. Under the standard treatment, disease incidence was higher and productivity reached 25.4 t/ha. Under control conditions, moisture content varied from 72.2% to 79.9%, while starch content ranged from 10.8% to 16.4% and protein content from 1.3% to 1.6%. Colomba recorded the highest yield under control conditions (836.7 g/bush), and maintained the highest yield under disease conditions (720.0-796.7 g/bush). Differences in yield among varieties and treatments were assessed using analysis of variance (ANOVA), followed by the Games-Howell post hoc test in IBM SPSS Statistics.