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Does increasing plant population density alter sugar yield in high stalk-sugar maize hybrids?

Ma, B.L., Zheng, Z.M., Morrison, M.J. (2017). Does increasing plant population density alter sugar yield in high stalk-sugar maize hybrids?, 68(1), 1-10.


© 2017 CSIRO. Escalating demands for food and green energy have renewed interest in the dual-purpose use of maize (Zea mays L.) for a biofuel and high-energy forage crop. Recently, maize hybrids with high stalk-sugar (sugarcorn) have been developed. It is important to determine how agronomic practices, for example altering plant population density (PPD), affect stalk-sugar yields of these newly developed hybrids and to advance knowledge required for producing sugarcorn as a dual-purpose bioenergy-high energy silage crop in short-season regions unable to grow sugarcane. A field experiment was conducted for 3 years to assess the effect of PPD on stalk-sugar accumulation, dry matter production, silage and sucrose yields of sugarcorn compared with two commercial silage hybrids. Targeted PPD ranged from 75000 to 150000 plants ha-1 in increments of 25000 plants ha-1. We found that increasing PPD from 75000 to 125000 plants ha-1 increased stalk sugar concentrations by up to 25% in some of the sugarcorn hybrids, with minimum change in the conventional check hybrids. The sugarcorn hybrid CO348×C103 had the highest stalk sugar concentration (128gkg-1) and sucrose yield of up to 3.8Mgha-1 at the targeted PPD of 125000 (or actual 118000±7000) plants ha-1. By contrast, the check silage hybrids produced at most 2.0Mgha-1 of sucrose yield with much lower stalk sugar concentrations (53-65gkg-1). Sugarcorn hybrids had generally lower grain yield with greater plant barrenness (the failure of a plant to produce a normal ear) and severer head smut infestation than the conventional silage hybrids. Our results suggest that as a silage crop, the current recommended PPD of 75000-85000 plants ha-1 for commercial silage maize production in the region is likely suitable for sugarcorn, and a higher PPD is required if sugarcorn hybrids are designated as a biofuel crop or for dual-purpose use.

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