ECOTYPES OF MAIZE FROM THE STATE OF PUEBLA, MEXICO AND THEIR RELATION TO AN INDEX OF ARIDITY

Abstract

Maize (Zea mays L.) thrives in both tropical and subtropical conditions, even in environments with limited water availability. In Mexico, maize production is primarily carried out under rainfed conditions, particularly in arid regions. The objective of this research was to identify ecotypes with better adaptation to heat and water stress by analyzing the correlation between morphological and racial characteristics with the global aridity index (GAI). One hundred sixty one samples from 28 maize racial groups were analyzed. The ecotypes were collected between 2008 and 2011 in 137 communities of 38 municipalities of the state of Puebla, Mexico as part of the “Master Project of Mexican Maize”. Data were filtered by verifying the consistency of morphological and climatic variables, removing incomplete records, duplicates, or with georeferencing errors. With the validated information, thematic maps were generated to display geographic distribution of the ecotypes and GAI values, developed with the R programming language. The GAI was obtained from the CGIAR platform and allowed the identification of arid sites in each state. Most of the collection sites exhibited values between 0.2 and 0.7 and were classified as arid to humid areas according to the GAI scale. Three percent of the ecotypes were located in arid areas, while 12 % were located in humid areas. A positive association (r = 0.23-0.61; P ≤ 0.05) between phenological, vegetative, and ear traits with the GAI was found, indicating a moderate association between morphological variation and aridity conditions. Ecotypes belonging to the races Chalqueño, Olotillo, Ancho and Pepitilla showed better adaptation to arid climates and water stress conditions. These accessions could be used as base germplasm for breeding programs aimed at developing heat- and drought-tolerant maize.