Development of Semi-exotic Maize (Zea mays L.) Inbred Lines: Performance per se and in Hybrid Combinations

Abstract

To create positive transgressive segregation of quantitatively inherited traits such as yield of inbred lines, two or more sources which accumulate different classes of favorable alleles are required. Introgression of exotic germplasm into tropical inbred line is one of several possible methods. This study was conducted to asses a potential use of exotic germplasm introduced from different latitudes to improve tropical inbred lines and their performance in hybrid combinations. The results of the present study indicated that all improved exotic germplasm were equally useful as sources of desirable alleles, especially for high yield of semi-exotic inbred lines. The 25 % semi-exotic inbred lines showed earlier days to anthesis and silking, lower grain moisture content, but higher leaf disease infection than the 12.5 % semi-exotic inbred lines. Transgressive segregation of semi-exotic inbred lines was also found in each class of exotic germplasm. Testcross hybrids generated from crossing between tropical testers with 12.5% exotic inbred lines showed higher yield, earlier maturity, and better disease resistance than the testcross hybrids of 25 % exotic inbred lines. Result of the present study suggested that combining ability of recurrent parent and the tester as well as proportion of exotic alleles in the converted semi-exotic lines are very importance for a success of semi-exotic inbred lines in hybrid combinations.