Submitted to: Crop Management at www.cropmanagement.org
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2003
Publication Date: 8/29/2003
Citation: SINGER, J.W., TAYLOR, R.W., BAMKA, W.J. CORN YIELD RESPONSE OF BT AND NEAR ISOLINES TO PLANT DENSITY. CROP MANAGEMENT at www.cropmanagement.org. 2003. Available from: http://www.plantmanagementnetwork.org/pub/cm/research/2003/density/www.cropmanagement.org
Interpretive Summary: Optimum plant densities for Bacillus thuringiensis (Bt) corn should be higher than non-transgenic corn subjected to European corn borer (ECB) damage because of reduced stalk lodging. Yield increases for Bt corn ranged from 0 to 10% in 2000 and 2001 compared to non-Bt corn. Relationships between grain yield and plant density did not reveal a consistent response. The inability to identify different optimum densities for Bt and non-Bt corn may have been due to low stalk lodging, plant density treatments that did not maximize yield in most instances, or the absence of different optimum densities. Bt corn provides a yield advantage compared to non-Bt corn when ECB damage is moderate to high. Hybrid tolerance of ECB damage varies. Corn producers should use Bt corn in fields that have a history of ECB damage or where management practices may increase ECB damage. Additional research is needed to determine if different optimum plant densities exist for Bt and non-Bt corn before revising plant density recommendations. These results support previous research that newer corn hybrids respond to high plant densities.
Technical Abstract: Optimum plant densities for Bacillus thuringiensis (Bt) corn (Zea mays L.) should be higher than non-transgenic corn subjected to European corn borer (ECB; Ostrinia nubilalis Hübner) damage because of reduced stalk lodging. The objectives of this research were to determine if yield differences occurred in Bt compared to near isoline hybrids and to determine if different optimum densities exist for Bt and near isolines. Bt hybrids were compared at target densities ranging from 20,000 to 36,000 plants/acre at different mid-Atlantic locations in 2000 and 2001. Yield increases ranged from 5 to 8% in 2000 at all locations. In contrast, Bt corn performed better than near isolines at only one of three locations in 2001, with a 10% yield advantage. Relationships between yield of near isolines and ECB damage were weak. Plant density affected yield at all locations in both years. Regression analysis of grain yield on plant density did not reveal a consistent hybrid response, although some evidence exists that suggests Bt hybrids are more efficient than near isolines at producing yield as plant density increases. The inability to identify different optimum densities for Bt and near isolines may have been due to low stalk lodging, plant density treatments that did not maximize yield in most instances, or the absence of different optimum densities.