Biometria aplicada à seleção de progênies parcialmente endogâmicas de milho pipoca

Abstract

Popcorn differs from corn essentially because of the popping expansion capacity the beans have. This character is related to the quality of the final product and should be prioritized along with the components of grain yield in breeding programs. Thus, knowing the association between the various characters that are measured in the countryside is important, since they can aid the selection of genotypes with two or more characters of interest. This work was carried out with the objective of evaluating the cause and effect relationships between grain yield, popping expansion capacity, volume of popcorn expanded per hectare and other morphoagronomic characters through path analysis and compare different selection indexes methodologies as a tool for the prediction of gain prediction with the selection of partially endogenous progenies of popcorn. For this, 23 progenies S2 of popcorn were used from the germplasm bank of the Plant Breeding and Biotechnology Program of the Universidade Federal da Grande Dourados. The progenies were installed in a randomized complete block design with three replicates. The evaluated characters were height of plants (HP), height of insertion of the first cob (HC), number of plants bedridden and broken (BB), cob number per plot (CN), grain yield (GY), mass of 1000 grains (M1000), popping expansion (PE) and volume of popcorn expanted per hectare (VP). No genetic correlation was verified between PE and GY. However, a positive linear association of these two characters with VP was found. The path analysis performed with the VP character as the main one, presented the best option to obtain simultaneous gains in PE and GY, since the direct effect of these characters on PV was positive. The use of different selection indices allowed the prediction of simultaneous gains in all the characters. The best results observed with the indices were obtained with the use of arbitrary empirical weights. The selection of progenies based on the indexes Mulamba and Mock (1978) and Genotype-ideotype, showed greater possibilities of simultaneous gains in the characters of interest. The use of PV in path analysis and selection indexes provided satisfactory results, since it allowed the selection of progenies with good grain yield and popping expansion, and could be used as an auxiliary character in the breeding programs of this crop.