Assessing maize diversity and defining a representative subset by means of selected morphological ear traits

Abstract

The objectives of this study were to analyse the maize diversity in the southeast of Coahuila State in Mexico and to identify a representative subset that encompasses the majority of the diversity in the region of study. Seventy-seven native maize populations were first explored and given a race classification followed by a morphological description based on selected quantitative ear traits using 10 representative ears from the collected samples. The differences between maize populations from the adaptation area and the relationships between and within groups in the region of study indicate the usefulness of the ear traits to describe maize diversity. Two main groups were identified that summarized the maize diversity. The first group, the conical ear complex, includes populations adapted to highland altitudes (Conico Norteño Race). The second group, the cylindrical ear complex, represents populations adapted to lowland and intermediate altitudes (Raton and Tuxpeño Norteño). Using the phenogram, a subset of 18 out of the 77 maize populations (23.4%) was defined that accounts for the variation between and within the different race complexes. This subset also includes at least one representative population from each of the less represented types. The final subset, representing a sample of maize diversity, can be used to establish strategies for conservation and use, such as participatory conservation and management, or it can be used to develop breeding techniques for improving the land race populations within the region of study.

Morphological Characterization of Native Maize Populations of the Ratón Race From Coahuila, Mexico

“…With the resulting matrix, a hierarchical cluster analysis was performed and a dendrogram was generated using the hclust function of the Factoextra package of the R software (Kassambara and Mundt, 2020) through the unweighted paired groups method using arithmetic averages (UPGMA). Based on the dendrogram, a modified stratified and directional sampling was performed (Rincón- Sánchez and Ruiz-Torres, 2018). This process was initiated by discriminating populations with the lowest values of distance between pairs of populations within groups, thus obtaining an initial representative subset of the total populations.…”

“…In this country, much of the maize diversity is found in the form of native populations in farmers' fields, in a wide range of environments, from sea level to altitudes above 2900 m, and from humid tropical environments to semi-desert conditions (Ruiz-Corral et al, 2008). The diversity observed in maize race traits is the result of farmer-directed selection aimed at meeting their consumption, socioeconomic, and production needs, in addition to adaptation to specific environmental conditions (Rincón- Sánchez and Ruiz-Torres, 2018). The measurement and analysis of morphoagronomic traits of native maize populations are very useful to know the phenotypic variation among and within races and among populations, and at the same time, to evaluate their stability in the environments (Flores-Pérez et al, 2015;Govindaraj et al, 2015).…”

“…The measurement and analysis of morphoagronomic traits of native maize populations are very useful to know the phenotypic variation among and within races and among populations, and at the same time, to evaluate their stability in the environments (Flores-Pérez et al, 2015;Govindaraj et al, 2015). Diversity studies in populations considered as variants of a race are of great relevance for defining conservation and use strategies, as well as for the identification of alleles that contribute to improve productivity within regions (Rocandio-Rodríguez et al, 2014;Rincón-Sánchez and Ruiz-Torres, 2018). According to passport data, the diversity of native maize in the state of Coahuila is represented by seven races: Celaya, Cónico Norteño, Elotes Cónicos, Olotillo, Ratón, Tuxpeño, and Tuxpeño Norteño.…”