Biomass yield and cell wall composition of corn with alternative morphologies planted at variable densities

The demand for biofeedstocks is increasing with the growth of the biofuel industry. Mutations such as grassy tillers1 (gt1), which increase the number of primary lateral branches (tillers) from below ground nodes, as well as Corngrass1 (Cg1), which alters cell wall composition, are hypothesized to increase theoretical ethanol yield on a per hectare basis. To test this, gt1 isogenic hybrids and Cg1 hybrids were evaluated at two densities (20,000 and 70,000 plants ha^-11). Stover samples were collected at grain physiological maturity and evaluated for cell wall composition. The effect of density treatment was significant for grain, stover, whole plant yield, and acid detergent lignin (ADL) on the whole data set (p = 0.05). Negative correlations were observed between stover yield and cell wall composition traits, while positive correlations were observed among compositional traits. The Cg1 hybrids were the lowest yielding hybrids and had higher ADL than the commercial checks. Tiller number was positively correlated with grain, stover, and whole plant yield at the low density. Homozygous gt1/gt1 hybrids planted at low density were not different than their wild-type counterparts planted at high density for stover yield. The ability of tillering plants to equate biomass production of their wild-type counterparts at nearly four times higher density demonstrates the utility in exploring alternative plant morphologies in an effort to meet the needs of the biofuel industry.