Drought stress intensifies early blight and compromises potato yield

Area of Science:

• Plant Pathology
• Agronomy
• Genetics

Background:

• Investigated the impact of water stress on early blight (EB) disease severity and potato yield across 44 genotypes.
• Field study conducted over two years (2021-2022) in Esfahan, Iran, comparing conventional irrigation with a 30% water reduction.
• Evaluated disease severity percentage (DSP) and yield components (total, marketable, nonmarketable) in susceptible and resistant cultivars.

Purpose of the Study:

• To assess the combined effects of water stress and early blight disease on potato performance.
• To identify potato genotypes exhibiting resistance to both drought and EB.
• To provide guidance for breeding programs and irrigation management strategies.

Main Methods:

• Utilized a strip-plot design within a randomized complete-block design with three replications.
• Applied water stress by reducing irrigation by 30% compared to conventional methods.
• Analyzed disease severity percentage (DSP), yield components, and correlated these with water stress and genotype resistance. Phylogenetic analysis of Alternaria alternata isolates was performed using the gpd gene.

Main Results:

• Water stress significantly increased DSP (from 28 to 36 ton/ha) and reduced total yield (by ≈26%).
• Susceptible genotypes showed marked increases in DSP under water stress, while resistant genotypes exhibited minimal changes.
• A strong positive correlation was found between water stress and disease severity (r=0.927**), and between water stress and total yield (r=0.668**).

Conclusions:

• Selection of potato genotypes resistant to both drought and early blight is essential for managing combined abiotic and biotic stresses.
• Optimizing irrigation timing, particularly during tuber development, can alleviate negative impacts of drought.
• Findings support breeding efforts and integrated disease management for enhanced potato resilience in variable climates.