ECO-PHYSIOLOGICAL RESEARCH OF CORN UNDER RAINFED CONDITIONS IN THE HIGHLAND REGION OF NORTHERN MEXICO

Abstract

The highland region in the North-Central part of Mexico includes mainly the states of Zacatecas, Durango, San Luis Potosi, Aguascalientes and North of Guanajuato. In this region, 760, 000 ha are sown with maize (Zea mays L.) under rainfed conditions. Approximately, 400, 000 ha in this region have 250 to 400 mm of rainfall over a period of 80 to 100 days; in the remaining area (360, 000 ha), the rainfall goes from 400 to 500 mm, over a period of 100 to 120 days; in both areas average temperatures are ranging from 15 to 20ºC. Seventy percent of the rainfall is registered before anthesis, and 30 % after it. Fifty two percent of the highland soils have depths of 50 cm or less, and 46 % have 50 to 100 cm, with an organic matter content lower than 1 %; therefore, moisture storage capacity of soils in the area is very low. These ecological characteristics are lower than the best ones for a satisfactory maize growing; for this reason in this region of Mexico most of the eco-physiological research in rainfed corn have been carried out. In the present work the drought type is defined, and a summary of the eco-physiological research in rainfed corn already carried out is presented, to observe the corn breeding orientation, and to improve corn breeding methodologies.