Reactions of seventeen hybrids and fourteen lines of corn to common smut disease

Common smut is the most important disease of maize in Iran and in many parts of the world. Since the best way to control this disease is identification and cultivation resistant varieties, 17 hybrids and 14 lines were tested in a field experiment as split plots in random complete block design with 4 replications. Plants were inoculated artificially by injection of spore suspension Ustilago maydis into the tip of ears at the time of tassel appearance. The reaction of lines and hybrids to the pathogen was determined as the percent infection of ears and disease severity, after the appearance of disease symptoms on ears. Also, the effect of disease on yield, 1000 grain weight, ear length, chlorophyll and florescence chlorophyll was measured. Statistical analysis of the data showed that there was a significant difference between hybrids and lines in reaction to disease such that among the hybrids there were, 3 sensitive, 7 semi sensitive, 6 semi resistant and resistant hybrid (K3547/3×K1264/1), while among 14 tested lines, there were 1 sensitive, 8 semi sensitive and 5 semi resistant to disease. Also, the disease significantly decreased yield, 1000 grain weight and ear length in hybrids and lines. Reactions of these maize hybrids and lines to this disease and the effect of the disease on their agronomical characteristics are reported here for the first time.