Selection indexes for yield forage maize.

Abstract

The objective of this research was to estimate selection indexes of agronomic traits that help in selecting the genetic material used in the production of forage, and evaluate the relative efficiency of the indexes estimated. We evaluated 28 direct crosses (Griffing’s method IV), the product of diallel crosses design with eight lines of high quality protein maize (QPM).The study was done in the Rancho Ampuero in Torreon, Coahuila, Me xico, in 2003 and 2004. The experimental designwas a randomized complete block with two repe titions, the variables evaluated were: plant height (PH), ear height(AM ), green forage yield (RFV) and dry forage yie ld (RFS).It was found: a) greater efficiency by combining characters correlated with the trait of interest, b) the correlation between characters per se, causes decreases in the efficiency of the index, c) the theoretical response to the selection was greaterwhen using selection indices than when done solely on forage yield, d) the most efficient selection indices took into account the yie ld of green fodder and those varia bles with the highestgenetic correlation (AP and AM ), e) the index selected included the variables plant height, ear height and forage yield(I=-20,88 X1 +49,26 X2 -0,11 X3) with a relative efficiency of 1,5 7%.