EVALUATION OF CORN FAMILIES FOR THEIR TOLERANCE TO SPACELOTHECA reiliana (Kuhn) Clint IN JALISCO

Abstract

Maternal half-sib  families derived from two bread genetic base populations (PABG) of ma ize from El Bajio, PAABG-Late and PABG-Intermediate, were tested to asses their reaction to head smut Sphacelotheca reiliana (Kuhn ) Clint. The study was carried out at Zapopan, Jalisco, planting under residual soil moisture conditions in 1985. Seed and soil were inoculated with theliospores. The commercial hybrid H-311 was plantad between groups of 10 familias each as a check. Head smut incidence (%) in the families was estimated considering all the plants showing fungus development on the tassel, ear or both organs.There were 31 families from PABG-Late and 17 from PABG Intermediate that showed no fungus development.The average head smut incidence for PABG-Late and PABG-Intermediate respectively, were 17 and 21% , respectively and the variability of fungus incidence was largar in the PABG-Intermediate . The correlation coefficients between head smut and yield were -0.40** and -0.58** while for head smut and stalk rot were -0.09* and -0.016** for the PABG-Late and PABG-Intermediate, respectivaly. Twenty familias without head smut were selected from PABG-Late to form a new population. In 1986 this new population only had 5% of head smut as compared to 16% of tha PABG-Late.