ABORDAGEM MULTIVARIADA DA QUALIDADE FÍSICA E FISIOLÓGICA DE SEMENTES DE MILHO HÍBRIDO AFETADAS POR MOLICUTES MRFV

Abstract

In view of the damage caused by the corn stunt complex disease (molicutes and MRFV) to the crop plants development, it is necessary to exclude its effect on its seeds quality. Thus, this study aimed to investigate through the multivariate approach to the attributes of physical and physiological qualities, changes in the vigor of seeds of different hybrids and severity levels resulting from the corn stunt complex (molicutes and MRFV), with the goal to select seeds of high vigor and hybrids more tolerant to the disease. In addition to identifying through multivariate statistics the main indicators of vigor. Seeds of three corn hybrids, hybrid 1 (H1), hybrid 2 (H2) and hybrid 3 (H3), were used for the study, each one with three levels of ear severity being sound, medium severity and high severity from ears of seed production fields affected by the pathogen. Seed quality was assessed using attributes of physical and physiological quality. The data obtained were subjected to analysis of variance and, when significant, studied through factor analysis (FA), scott-knott test (p <0.05) for the selected indicator variables and cluster analysis (CA). The classification in ear severity levels and joint analysis of the data through multivariate analyzes, FA and CA, proved to be efficient to distinguish difference in seed vigor in this study, as it was possible to detect a gradual reduction in the quality attributes used to evaluate seed vigor. The seeds coming from ears with medium and high severity of the corn stunt complex (molicutes and MRFV) were less vigorous than the sound ones (asymptomatic, with normal development) for the tested hybrids. Comparing the hybrids to each other depending on the severity level, the H2 hybrid was more susceptible and the H1 hybrid more tolerant to molicutes and MRFV. Of the 37 variables analyzed, seven were considered to have the greatest indicator potential, most relevant in explaining changes in seed performance (H, TSM, SDMSL, RDM, SDM, AA and β-amy), these belonging to the two different attributes studied, physical and physiological, emphasizing the importance of the two segments for quality control and genetic improvement programs during the selection of high vigor seeds and hybrids more tolerant to corn stunt complex disease.