Preliminary Trial Studies Using Chlorophyll Meter (SPAD) For Monitoring Stripe Rust Disease in Winter Wheat Under Greenhouse Conditions

Background/Aim: This study was conducted under greenhouse conditions to evaluate the effects of different yellow rust (Puccinia striiformis) inoculum doses on disease severity (DS%) in wheat genotypes at the seedling stage.Methods: The plant material comprised resistant genotypes, including Triticum spelta album (Yr5), Cortez (Yr15), and Eminbey (durum), and susceptible genotypes, Little Club and Morocco. At the second leaf stage (Zadoks growth stage Z11-12), plants were inoculated with a spore suspension of the pathogen homogenized in mineral oil. Inoculations were performed on 21 March 2019, applying doses of 0% (control), 25%, 50%, and 100% of a standard spore concentration. The first disease symptoms appeared 15 days post-inoculation. Results: Evaluation of the relationship between Disease Severity (DS%) and SPAD measurements revealed high correlation coefficients (R²) across different time points. In the resistant genotypes, strong correlations were observed early (06 April 2019) for Eminbey (R² = 0.943), Triticum spelta album (Yr5) (R² = 0.775), and Cortez (Yr15) (R² = 0.730). These remained high in the early-mid period (08 April 2019) for Eminbey (R² = 0.994), T. spelta album (R² = 0.859), and Cortez (R² = 0.856), and finally in the late period (12 April 2019) for T. spelta album (R² = 0.980), Eminbey (R² = 0.795), and Cortez (R² = 0.635). Similarly, the susceptible control genotypes, Little Club (LC) and Morocco, also showed high correlations in the early (R² = 0.996 and 0.951, respectively), early-mid (R² = 0.864 and 0.823), and late periods (R² = 0.963 and 0.727).Conclusion:. In conclusion, this study developed robust regression equations that effectively estimate disease severity at the seedling stage. These reliable models can contribute to determining optimal disease control strategies and application timing.