Potential for simultaneous improvement of corn grain yield and stover quality for cellulosic ethanol

Corn (Zea mays L.) stover, the residue left after harvest, is an abundant biomass source for producing cellulosic ethanol in the United States. Corn has been bred for increased grain yield but not for stover quality for cellulosic ethanol production. Our objective in this study was to assess the feasibility of breeding corn for grain yield and agronomic traits as well as stover quality traits for cellulosic ethanol production. Testcrosses of 223 B73 × Mo17 recombinant inbreds were evaluated at four Minnesota locations in 2007. Three stover quality traits were measured: concentration of cell wall glucose in dry stover ("Glucose"); cell wall glucose released from the stover by thermochemical pretreatment and enzymatic saccharification ("Glucose Release"); and concentration of lignin on a cell wall basis ("Lignin"). Genetic variances were significant for grain yield, moisture, stalk and root lodging, plant height, and all three stover quality traits. Heritabilities of the stover quality traits were 0.57 for Glucose, 0.63 for Glucose Release, and 0.68 for Lignin. Pheno-typic and genetic correlations were favorable or neutral among grain yield, agronomic traits, Glucose, Glucose Release, and Lignin. Lines selected with a multiple-trait index for grain yield, agronomic traits, and stover quality traits had improved means for each trait in the index. Current corn breeding programs should be able to incorporate stover quality for cellulosic ethanol as a breeding objective, without having to use unadapted or exotic germplasm and with-out adversely affecting genetic gains for grain yield and agronomic traits.