Caracterización morfoagronómica y fisicoquímica de 15 accesiones de maíz (zea mays l.) con fines de fitomejoramiento

Abstract

The objective of this work is the morphoagronomic and physicochemical characterization of 15 maize accessions, collected in the province of El Oro, which are conserved in the germplasm bank belonging to the Faculty of Agricultural Sciences, in order to know the existing diversity and its agronomic potential, which will serve as a basis for future breeding programs and, in turn, contribute to the preservation of the genetic diversity of maize. For morphoagronomic characterization, data were collected for 5 qualitative and 21 quantitative descriptors. The morphoagronomic variables studied were: days to anthesis, days to stigma emission, plant height (cm), ear height (cm), rib index, ear length (cm), peduncle length (cm), ear branched length (cm), number of primary and tertiary branches on the ear, leaf length and width, ear length and diameter (cm), peduncle length (cm), number of kernels per row, number of rows per ear, kernel length and width (mm), kernel row arrangement, kernel color, pericarp and endosperm, kernel type and thickness (mm); As for the physical-chemical characterization, the following were determined: ash percentage, fat percentage, amount of phenols, antioxidant activity and protein percentage. Once the morphoagronomic characterization data were collected, the matrix was designed and subsequently standardized to obtain the correlation table, which was used to generate the structure of the dendrogram based on Euclidean similarity distances; the analyses were carried out with the IBM SPSS Statistics 25 program. By means of principal component analysis (PCA), it was possible to establish the discriminant characters that describe the most differentiated values to analyze phenotypic diversity, these being: days to anthesis DHA, days to stigma emission DHEE, rib index IN, female peduncle length LPF, leaf length LH, ear length LMZ, number of rows per ear NHMZ, grain width AG, grain length LG, endosperm color CEN, grain type TG, these variables have a relationship with the beginning of the reproductive stage, plant structure and grain characteristics. As a result, five well-defined groups were identified, evidencing a very good phenotypic diversity among the accessions studied; group one turned out to be more numerous with 8 accessions, it can be attributed to the fact that they are conformed by: ear length and kernel thickness, kernel color, pericarp color, endosperm color, kernel type, proteins; a more distant group with greater variance was determined, composed of a single accession, UTMACH-066, denominated by average and differentiated values of all the accessions evaluated. Regarding the physicochemical analysis, the accession UTMACH 058, 089 presented a high percentage of phenols and antioxidant activity in comparison with the other accessions, the accession UTMACH 048 and 065 have the highest weight in the 100 grains (31.60g and 30.75g), the accessions with semi-crystalline endosperm characteristics presented higher protein content, unlike the accessions of floury grain type.