COMPARISON. OF TWO SELECTION METHODS RECURRENT IN CORN

Abstract

Aiming to compare the genetic gains for yield when applying two methods of recurrent selection on an indigenous maize (Zea mays L.) called Xnuc-Nal, during 1983 and 1984 the following maize varieties were evaluated: Original variety (C_o) and the cycles SMC₃, SMC₄, SFC₁ and SFC₂; SMC₃ and SMC₄ were obtained by mass selection and SFC₁ and SFC₂ by modified ear to row selection. The evaluation was carried out in the Yucatán Península of México under three environmental conditions per year under slash and hum type of agriculture. The statistical analysis showed significant differences for yield among selection cycles and highly significant differences for the varieties by environment interaction. No gains in grain yield was obtained after four selection cycles of mass selection with a coefficient of regression of 5.61 kg/ha/cycle whereas with modified ear to row selection a 7.2% yield increase was obtained per each selection cycle with a regression coefficient of 128.54 kg/ha/cycle. The foregoing indicates that for the karstic stony environmental local conditions, the modified ear to row selection might be the best alternative to continue with the genetic improvement of indigenous maize.