José Luis Ramírez Díaz

Identificación de razas mexicanas de maíz adaptadas a condiciones deficientes de humedad mediante datos biogeográficos

We worked with a database of recent accessions of 54 races of maize from Mexico, whose passport details were extracted from the Genetic Resource Unit from INIFAPs Germplasm Bank. From the geographical coordinates of the accessions, was made an accession characterization by site, conditions of moisture availability for the period from May to October for the development of maize, based on the environmental information system from INIFAP and the IDRISI Andes system. With these data, a statistical analysis was made that included an analysis of variance and analysis of numerical taxonomy (cluster analysis) with the product moment correlation between races. Additionally was performed an accessions analysis by race to identify the accessions that developed under moisture-deficient environments. Accessions were selected with adaptation to an environment with humidity index (IH) (precipitation / potential evapotranspiration) from May to October less than 0.5. The results showed the identification of five racial groups, of which one of them stood out for its adaptation to an HI between 0.39 and 0.53. This group included Chapalote, Dulcillo Northwest, Tuxpeno Norteno, Conical Norteno, Tablilla of Ocho and

H-383 : híbrido de maíz blanco intermedio para grano y forraje para el norte, centro y occidente de México

In Mexico the demand for maize grain for human consumption and livestock is around 38 million tons; however, only between 25 and 28 million are produced, the rest are imported from the United States. Deficits in maize production are mainly due to the use of inappropriate varieties, poor crop management, and biotic and abiotic problems occurring regularly during the crop cycle. In view of the need for more productive hybrids, the National Institute for Forestry, Agriculture and Livestock Research (INIFAP) in the year 2 000 initiated a genetic improvement program aimed at obtaining hybrids of high yield of grain and forage, from which the hybrid was derived of single cross h-383 white grain formed by the combination of lines PAB7 and PAB8. The line PAB7 was derived from the PGB population and its pedigree is PGB-2-1-3-1-1-N1-3-b-b-b. The PAB8 line corresponds to the sub-tropical public line CML312 of the International Center for Maize and Wheat Improvement (CIMMYT) with three more generations of inbreeding for the selection of greater ear health. The hybrid has a yield potential higher than 15 t ha-1 of irrigated grain, and up to 12 t ha-1 in areas of good weather; produces between 24.7 and 26 t ha -1 dry matter, with values between 71 and 74% in digestibility and between 40 and 48% in fiber digestibility. It has adaptation in areas of irrigation of the North Central region of Mexico and the Bajio; as well as in good weather areas of the Center and West of Mexico, located between 1 600 and 2 000 meters above sea level. It is of intermediate cycle, leaves dark green and height between 3 and 3.2 m. The hybrid was registered in the National Service of Inspection and Certi fication of Seeds (SNICS) with the key: MAZ-1352-190712.