Effect of elevated temperature and carbon dioxide levels on maydis leaf blight disease tolerance attributes in maize

Abstract

In the present study, effect of elevated temperature and CO2 levels was assessed on maydis leaf blight (MLB) disease tolerance attributes of two maize genotypes PEHM 5 (moderately resistant) and CM 119 (highly susceptible). The maize genotypes were exposed to two CO2 levels: ambient (400ppm) and elevated (550±20ppm) and three temperature levels: ambient, 1.5°C higher than ambient and 3°C higher than ambient temperature throughout crop growth periods. Disease severity in CM 119 was higher than PEHM 5 in all treatments. The disease severity increased when temperature was increased 3°C higher than ambient temperature, but effect of temperature was subsided when CO2 concentration was increased from ambient to 550ppm level. Maximum (76.5% and 95.4%) and minimum (61.7% and 78.7%) disease severity in PEHM 5 and CM 119 was observed in 3°C elevated temperature and ambient CO2 level; and ambient temperature and elevated CO2 level, respectively. Six disease stress tolerance attributes were calculated based on yield under diseased (Ys) and without disease condition (Yp). Both Ys and Yp were positively correlated with disease stress tolerance index (DSTI), mean productivity (MP) and geometric mean productivity (GMP) and negatively correlated with disease tolerance (TOL) and disease stress susceptibility index (DSSI). Results showed that with the increase in ambient temperature, severity of MLB disease is likely to increase in future.