Genetic Potential of Exotic Germplasm Introduced from Different Latitudes for the Improvement of Tropical Maize (Zea mays L.)

摘要

To broaden the genetic base of the tropical maize, adding more favorable alleles from exotic germplasm into the tropical breeding material is one way suggested by plant breeder. For effective utilization of the exotic germplasm, rapid and efficient method of incorporation of exotic germplasm into tropical material is needed. This study was conducted to assess a genetic potential and the effectiveness of exotic germplasm introduced from different latitudes in combination with tropical breeding materials. The results of the study implied that: semi-exotic populations containing 50 % exotic germplasm showed the lowest yield, lowest grain moisture content, earliest days to anthesis and silking, highest leaf disease infection. Semi-exotic populations with 25 % and 12.5 % exotic germplasm showed no significant difference to population with 0 % exotic germplasm, except semi-exotic population of latitude-2 ( > 22.5 - 37.5°North Latitude), Southern U.S. germplasm. Significant quadratic response among population means due to proportion of exotic germplasm was noted for grain yield of the semi-exotic populations of latitude-1 ( >37.5°N.L.), -2, -3 ( > 7.5- 22.5 °N.L.), and -5 ( > 37.5°South Latitude). Significant linear responses were noted for days to anthesis and silking and grain moisture content. Highly significant linear response to leaf diseases was observed in semi-exotic populations of latitude-1, -2, -3, -4 ( > 22.5 -37.5 °S.L.), and significant response was shown by exotic source from latitude-5. Population with 50% exotic germplasm from latitude-4 "South Africa" was well adapted to tropical condition and showed no response to the higher degree of tropical germplasm.