Development of multiple disease resistant corn populations
2003
Pascual, C.B. | Salazar, A.M. (Philippines Univ. Los Banos, College, Laguna (Philippines). Inst. of Plant Breeding)
Several damaging diseases caused by bacteria and fungi endanger corn production in the Philippines. Some of them include bacterial stalk rot, banded leaf and sheath blight and downy mildew. Search for new and more effective genes for resistance to the important corn pathogens and transfer of these to breeding populations were conducted to develop multiple disease resistant corn inbreds and populations. Yellow and white corn breeding materials consisting of advanced populations, inbred lines, parentals and hybrids were screened for resistance to downy mildew, bacterial stalk rot and banded leaf and sheath blight by artificial inoculations. A total of 735 yellow lines (S2 to S6) and 882 white materials were tested in 1995-1996. Selection for resistance to one or more diseases was made and they were subsequently selfed. Top crosses from 243 selected resistant white inbreds and 26 selected resistant yellow inbreds were conducted in 1997. The hybrids were tested for resistance to the diseases. In 1998 wet season, 1,218 white double crosses resistant to downy mildew and having some hybrids with moderate resistance to bacterial stalk rot and banded leaf and sheath blight were recombined. Sixty-seven yellow double crosses with resistance also to one or more diseases were combined in 1998-99 dry season. The yield and yield component characteristics were measured. Four entries from white double crosses which were high yielders (6 to 7.2 tons/ha based on area yield) were resistant to both bacterial stalk rot and downy mildew. Six developed white inbreds (P37-1-2-5-1, P37-1-6-3-1, YIF62-3-1-3-1-1-5-2-1, YIF62-3-1-1-5-4-4-2, Pioner 10-1-5-1-1 and Pioner 14-2-1-4-1-1) were confirmed to have resistance to both diseases also. Twenty yellow corn hybrids were found to have high degree of resistance to banded leaf and sheath blight. This study resulted to the development of inbred, hybrids and populations with resistance to one or more important corn diseases especially in white materials
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