AGRONOMIC EVALUATIONS OF MAIZE GENOTYPES SELECTED FOR EXTREME FIBER CONCENTRATIONS

Maize (Zea mays L.) hybrids with good yields of grain and whole-plant dry matter are recommended for silage production. The stover can compr ise more than 50% of the whole-plant dry matter and, therefore, can in fluence dry matter yield and nutritive value of the whole plant. The o bjective of this study was to determine relationships between agronomi c characteristics (stover and whole-plant forage yield and moisture, g rain yield and moisture, lodging, maturity, and ear percentage) and nu tritional quality of maize forage in three populations. Twenty-four S- 0.1 families (S-0-derived families in S-1) exhibiting a range in neutr al detergent fiber (NDF) and lignin at mid-flower, were testcrossed to two commercial inbred lines (FR23 and LH74) to form two groups of F-1 hybrids. A third experimental group was cre ated by self pollinating the S-0.1 families to form S-0.2 families. This germplasm was evaluate d at three environments in Wisconsin. For FR23 testcrosses, grain yiel d had a correlation coefficient of 0.53 with stover dry matter yield, 0.65 with whole plant dry matter yield, and -0.03 with whole-plant in vitro true digestibility. For LH74 testcrosses, the similar correlatio n coefficients were 0.46, 0.54, and -0.02, respectively. Also for FR23 testcrosses correlation coefficients of stover yield with whole plant yield, NDF, and in vitro true digestibility were 0.89, 0.53, and -0.2 8, respectively. For LH74 testcrosses the coefficients were, 0.85, 0.4 0, and -0.48, respectively. The results of this study demonstrate that stover yield and nutritional quality are important factors influencin g whole-plant yield and nutritional quality of maize forage.