MASS SELECTION AS A METHOD TO OBTAIN MAIZE LINES WITH HIGH SPECIFIC COMBINING ABILITY

Abstract

The objectives of this work were to prove that the México Grupo 10 maize (Zea mays L.) variety, subjected to 6 cycles of stratified mass selection (C₆), is more capable than its original version (C₀) to produce inbred lines of high yield and high general and specific combining ability (GCA and SCA), and to estimate the phenotypic correlation between yield per se and GCA of inbred lines. In order to accomplish these purposes, 30 S₃ lines were obtained from C₀ and 30 S₃ lines from C₆ to make two groups of 30 topcrosses each using as tester C₀. It was also obtained 25 single-crosses in chain crosses way (1x2, 2x3,..., 25x1) within each group of inbred lines. The two groups of 60 S₃ lines, 60 topcrosses and 50 single-crosses were evaluated during the spring-summer season in 1998, at two localities in the State of México, under irrigation conditions, in a complete random block design with four replications. Results showed that the improved variety C₆ produced a higher frequency of high yield single-crosses (SCA) than C₀. On the other hand, the highest frequency of lines of high yield per se, although not always coupled to superior GCA, arose from C₀. Because of it resulted a very low correlation value (r = 0.10) between yield of S₃ lines per se and the yield of its respective top crosses as a measure of GCA.