AGRO-MORPHOLOGICAL DIVERSITY OF CACAHUACINTLE MAIZE FROM THE HIGH VALLEYS OF MEXICO

Abstract

The Cacahuacintle maize race geographically is distributed in the Mexican central highlands and it is characterized by its floury grain; typical forms have been described; however, the information on the agro-morphological variation within sub-types is limited, as well as the differences between the variants from different regions. Thirty-nine populations of Cacahuacintle maize were collected in the states of Puebla (Ciudad Serdán), Tlaxcala (Ixtenco) and State of México (Calimaya, Techuchulco, Amecameca and San Felipe del Progreso) and field experiments were established at four agro-ecological environments in the years 2018 and 2019, in the State of Mexico (Texcoco and Ayapango) and Tlaxcala (Ixtenco). Twenty-four agro-morphological traits were recorded, which were subjected to combined analysis of variance and, from this, the variance components for genotypes (σ²_g), environments (σ²_e) and genotype by environment interaction (σ²_g×e) were estimated. Ten variables related to the dimensions of ear, grain and tassel structures presented repeatability values r = [σ²_g/(σ²_a + σ²_g×a)] larger than 0.7, which were considered appropriate to study the agro-morphological diversity. Principal component and cluster analysis were performed with these variables. The first two principal components explained 68 % of the total variance. In the plane defined by the first two principal components, three groups were formed based on grain size and shape, mainly: 1) Chalqueño maize populations which were included as a different morphological reference; 2) typical Cacahuacintle populations (Calimaya, Techuchulco, and Amecameca, State of Mexico, and Serdán, Puebla, predominantly) and 3) variants of the Cacahuacintle type but with a smaller or less rounded kernel (Ixtenco, Tlaxcala; San Felipe, State of Mexico); this approach was consistent with grouping obtained by cluster analysis. Genetic diversity between Cacahuacintle populations is broader than previously known, with variants associated with geographic origin.