Influence of Cold-Hardening and Soil Matric Potential on Resistance to Speckled Snow Mold in Wheat.

The influence of soil matric potential, cold-hardening temperature, and duration on resistance to speckled snow mold caused by Typhula ishikariensis in wheat was investigated. Six winter wheat lines were subjected to cold-hardening temperatures of 2 or 4°C for 1, 2, 3, or 4 weeks with soil matric potential of -0.1 or -0.01 MPa. Plants were inoculated with T. ishikariensis after cold-hardening, incubated at 10°C for 25 days in the dark, and then evaluated for regrowth. Overall recovery from snow mold was least when plants were hardened at 2°C for 1 week at -0.01 MPa and greatest when hardened at 4°C for 4 weeks at -0.1 MPa. Survival of plants following snow mold was greater when plants were cold-hardened at 4 than at 2°C and at -0.1 than -0.01 MPa soil matric potential. The greatest difference in survival among lines and correlation with field observations occurred when plants were hardened at 4°C at -0.1 MPa matric potential for 3 weeks. Understanding the influence of temperature and soil matric potential during cold-hardening on speckled snow mold resistance will be useful to breeding programs developing snow-mold-resistant cultivars under controlled environment conditions.