SELECTION OF FULL-SIB FAMILIES FOR FRESH MARKET CORN PRODUCTION

Abstract

Progeny tests were conducted at the Agricultural Experiment Station of the State University of Ponta Grossa throughout the 2005-2006 growing seasons, aiming at evaluating 369 full-sib families. The plots of the trials consisted of rows with a 4 m-length, spaced of 0.8 m between rows, with a population density of 50.000 plants ha-1. A completely randomized block design was used for progenies derived from 190 large and dry ears with 3 replicates, and for 179 intermediate ears with two replicates. The following characteristics of five ears of each progeny were assessed: mass, length and diameter of the ears with and without straw. A visual observation on the ears as to its general aspect has also been adopted herein. The correlations between these characteristics and the heritability for all characteristics evaluated on the harvested ears were estimated. There were significant differences among progenies for all response variables analyzed, with a great number of progenies showing a performance similar to the hybrids. The correlation between the characteristics of the ears at fresh market stage was found to be variable from medium to high. The estimated heritability varied from 0.46 for diameter of the ears without straw treatment to 0.60 for length of the ears with straw. The trial carried out with 190 progenies generated 17.37% of excellent ears, whereas that one comprised by 179 progenies resulted in 3.91% of excellent progenies ears as to its visual appearance. The proportion of excellent ears increased from 2.85% to 27.56% within a single selection cycle of full-sib progenies.