[Comparison of types of maize varieties developed by inifap in the central-western part of Mexico] | Comparacion de tipos de variedades de maiz desarrolladas por el INIFAP en la region centro-occidente de Mexico

Inglés. The INIFAP maize (Zea mays L.) breeding program for the central-western part of Mexico developed elite lines to make new experimental varieties of different types. The new varieties: synthetic varieties, double cross, three-way, and single cross hybrids, formed with late and intermediate elite germplasm, were compared for yield to commercial hybrids as controls. The varieties were evaluated in a total of 71 experiments established in subtropical and tropical environments of that region in 1990 an 1991. Combined analyses of variance were performed by years considering all the environments, as well as the subtropical and tropical environments. No significant differences for yield were found when double, three-way, and single cross hybrids were compared; however, single crosses had larger mean squares (variance) than the other two types of hybrids. Experimental varieties outyielded the commercial ones by 10 % and the hybrids to synthetic varieties by the same percentage. Most of the interactions between the hybrids and the environment were significant, which confirms environmental specificity for each type of hybrid. Also, the importance of heterosis was clear for all hybrids when lines of the two maturity groups and different genetic background were crossed. Subtropical environments were 19 % more productive than tropical ones, and were more promising for utilizing single cross hybrids in the spring-summer season

Español; castellano. El programa de mejoramiento genetico de maiz (Zea mays L.) conducido por el Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias en la region centro-occidente de Mexico, desarrollo lineas elite que originaron nuevas variedades experimentales de diferentes tipos. Se compararon los rendimientos de hibridos comerciales testigo contra las nuevas variedades que incluian sinteticas, hibridos dobles, hibridos trilineales e hibridos simples, formados de germoplasma elite de precocidad tardia e intermedia. Las variedades se evaluaron en un total de 71 experimentos establecidos en ambientes subtropicales y tropicales de esa region en 1990 y 1991. Se hicieron analisis de varianza combinados por anos, considerando todos los ambientes, los ambientes del subtropico, asi como los ambientes del tropico. No hubo diferencias estadisticas para rendimiento entre los hibridos dobles, hibridos trilineales e hibridos simples; sin embargo, estos ultimos presentaron una varianza mayor. Las variedades experimentales superaron a las variedades comerciales testigo en 10 %, y los hibridos a las sinteticas tambien en 10 %. La mayoria de las interacciones entre los diferentes tipos de hibridos con el ambiente fueron significativas, lo que confirma la especificidad ambiental para cada tipo. Asimismo, se encontro heterosis importante al combinar germoplasma divergentes por su origen y madurez, independientemente del tipo de hibrido. Los ambientes subtropicales fueron 19 % mas productivos que los ambientes tropicales y mas promisorios para utilizar cruzas simples en siembras de primavera-verano