GENETIC-STUDY OF THE FORAGE NUTRITIVE-VALUE IN THE LANCASTER VARIETY OF MAIZE

The genetic variance components of the Lancaster variety were studied with respect to the traits related to the nutritive quality of the sto ver and forage production. Sixty two half-sib families, each divided i nto three families of full-sibs, were used. Their offspring were studi ed in a single location over two years. The main goal of the experimen t was to determine how to maximize the total digestible dry matter yie ld. This character is composed of several traits related to the nutrit ive quality of dhe stover and to yield. Low heritabilities were found for all of these traits (stover dry mat ter digestibility=0.26; neutra l detergent fiber of the stover=0.35; digestibility of the cell wall c ontent=0.37; digestibility of the whole plant=0.20; ear yield=0.25; st over yield=0.20). The expected direct responses to selection were foun d to be somewhat higher in the production traits than in the stover qu ality trails due to their greater variability. The production traits w ere found to highly correlate with the total digestible dry matter yie ld (r ranging from 0.77 to 0.95), whereas the traits related to the nu tritive quality of the stover showed no significant correlations with this variable. Selection for more leaves, stalk diameter and plant hei ght would appear to be the best way to accomplish a greater correlated response in the total digestible dry matter yield. This would allow p lants to be chosen before flowering time, allowing crossing to be carr ied out with the selected plants.