Impact of Planting Density on Stalk Sugar and Other Agronomic Traits Among Contrasting Corn Hybrids.

Globally escalating demands for food and green energy have renewed interest in the dual-purpose use of corn (Zea mays L.) for a biofuel and high energy forage crop. AAFC has developed some new corn hybrids (sugarcorn) with significantly higher levels of stalk sugar than that found in commercial silage hybrids. A field experiment was conducted for three years (2013-2015) to assess stalk sugar and agronomic performance of these sugarcorn hybrids in comparison to commercial silage hybrids as affected by plant population density (PPD). We found that increasing PPD from 75 000 to 125 000 plants ha^-1 slightly increased stalk sugar concentrations, especially for some of the sugarcorn hybrids. Silage dry matter yield exhibited significant differences between hybrids and were marginally affected by PPD, with a decline trend from 100 000 to 125 000 plants ha^-1. Sugarcorn hybrid ‘CO348xC103’ had the greatest stalk sugar level (111 g kg^-1) and sucrose yield of up to 3.8 Mg ha^-1 at the PPD of 125 000 plants ha^-1. In contrast, the check silage hybrids produced at most 2.0 Mg ha^-1 of sucrose yield with much lower stalk sugar concentrations (53 to 65 g kg^-1). Our results suggest that as a silage crop, the current recommended PPD, 75 000 plants ha^-1 for commercial silage corn production in the region, is likely suitable for sugarcorn; and a high PPD is required if sugarcorn hybrids are designated for biofuel crop or for dual-purpose use.