HYBRID QUALITY AND YIELD DIFFERENCES FOR CORN-SILAGE IN PENNSYLVANIA

Differences among corn (Zea mays L.) hybrids for forage quality traits have been reported, but the stability of forage quality differences o ver diverse environments is not well documented. To evaluate hybrid st ability for yield and forage quality, nine commercial hybrids were eva luated at two locations in Pennsylvania in 1990 and one location in 19 91. All hybrids were harvested on the same day at the 2/3 milk line to black layer stage, depending on the hybrid. Whole plant and stover su bsamples were collected from each plot, chopped, dried, and ground for analysis. Forage analysis for crude protein (CP), acid detergent fibe r (ADF), neutral detergent fiber (NDF), and in vitro dry matter disapp earance (IVDMD) was performed using near infrared reflectance spectros copy (NIRS) on both whole plant and stover samples. Total digestible n utrients (TDN) was calculated based on the ADF concentration. Environm ental effects were significant for yield and all quality traits. Hybri d effects were significant for all traits except TDN, ADF, and NDF. Th e range among hybrids for whole plant IVDMD at individual locations wa s as high as 4.1 percentage units, but averaged over the three environ ments, the range among hybrids was 2.7 percentage units. Silage yield differences among hybrids, which ranged up to 2.6 tons/acre or 11.5% o f the mean, were larger on a percentage basis than any of the quality differences. The results of this study indicate that both yield and fo rage quality differences exist among commercial hybrids and that produ cers should consider both yield and quality attributes in selecting a hybrid for silage production.