[Selection for ear position index in four maize varieties (Zea mays L.)]
1988
Molina Galan, J.D. | Herrera Mendoza, R. | Cervantes Santana, T. | Martinez Garza, A.
Two early and two mid term maize varieties were divergent mass selected for relative ear height position (ear position index). The objetive was to determine in each variety the optimum ear position index relative to grain yield. The original and its corresponding mass selection composites in each variety were evaluated at the Colegio de Postgraduados Experimental Field in a complete randomized block design with six replications in 1982 and 1984. The results indicated a linear response to selection for ear position index according to the Hallauer and Miranda (1981) regression model. However, according to the Eberhart (1964) regression model the response to selection in the early varieties resulted linear in the high ear position index selection composites and quadratic in the low ear position index. The opposite was obtained in the mid term varieties. The ear position optimum index resulted proximate to 0.5 in the early varieties and proximate to 0.6 in the mid term varieties. It was also found that it is possible to obtain an optimum index without modifing other important agronomic characters such as plant height and days to flowering.
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