MORPHOLOGICAL VARIABILITY ANALYSIS OF NATIVE AND EXOTIC MAIZE IN HIGHLANDS OF MEXICO

Abstract

Tropical and subtropical maize (Zea mays L.) native from Mexico is an important source of useful alleles that could be different to those of the germplasm from the mexican high valleys, and that would help avoiding the effects of adverse factors and contributing to increase their adaptability. The aim of this study was to identify the morphological variation between adapted and non-adapted exotic maize populations to high valleys and some of their interracial crosses. The germplasm evaluated was nine original populations of exotic maize and their advanced selection cycles in high valleys, eight single crosses, two double crosses, one triple cross, the advanced generations of the crosses and four local checks. The evaluations were done in three environments under a randomized complete block design with three replicates; the experimental plot had two rows of 6 m, separated to 0.80 m and with 0.5 m between plants. Twenty-eight qualitative and quantitative characters were recorded. Principal component analysis, hierarchical grouping, discriminant analysis and the Tukey’s mean comparison allowed to identify six contrasting groups. Traits of morphological structure, plant earliness and ear characteristics explained the variability and clustering of the genotypes. The original exotic populations increased in height, were late-flowering and decreased their ear yield. In contrast, the selected populations showed higher ear yields, fewer days to flowering, lower plant height, more primary tassel branches and conical ears. These attributes could be incorporated into maize breeding programs for mexican high valleys or combined with the local germplasm to improve their adaptability and heterosis.