Submitted to: Agronomy Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/11/2010
Publication Date: 5/10/2010
Citation: Meyer, M., Pataky, J., Williams, M. 2010. Genetic Factors Influencing Adverse Effects of Mesotrione and Nicosulfuron on Sweet Corn Yield. Agronomy Journal. 102:1138-1144. Interpretive Summary: This work demonstrates the importance of functional cytochrome P450 (CYP) alleles, responsible for metabolism of certain herbicides, in sweet corn germplasm. Currently, some commercial sweet corn hybrids, inbreds, and breeding germplasm have mutant (i.e. non-functional) cyp alleles, predisposing them to herbicide injury and yield loss. Nevertheless, hybrids with mutant cyp alleles are still grown because of their superior agronomic or horticultural traits. The impact of this work is that it shows how to reduce yield losses from P450-metabolized herbicides; namely, careful consideration of the herbicide, the timing of application, and genotype at the CYP locus of the hybrids being grown.
Technical Abstract: Sensitivity to certain P450-metabolized herbicides in corn (Zea mays L.) is largely conditioned by a single cytochrome P450 (CYP) gene. Little to no research has been done to evaluate the effect of CYP genotype on sweet corn yield. Yield of 23 sweet corn hybrids of known CYP genotype was evaluated in 2007, 2008, and 2009 following postemergence applications of mesotrione, an hydroxyphenylpyruvate dioxygenase-inhibitor, or nicosulfuron, an acetolactate synthase-inhibitor, at two growth stages. Mesotrione and nicosulfuron were evaluated in separate experiments. Treatments included herbicide application during the V3 to V5 or V5 to V7 growth stages and a nontreated control. Crop injury, measured 7 days after treatment (DAT), ranged from 0 to 87% for mesotrione and 0 to 54% for nicosulfuron among CYP genotypes. Injury from both mesotrione and nicosulfuron was most severe following application during V3 to V5 growth stages on hybrids with mutant (nonfunctional) CYP allele(s). Only cypcyp hybrids suffered yield losses from mesotrione, ranging from 9 to 40%. Hybrids homozygous for mutant cyp alleles (i.e., cypcyp) were not evaluated for nicosulfuron because applications of ALS-inhibiting herbicides kill these hybrids. Nicosulfuron significantly reduced the yield of CYPcyp hybrids only. Yield losses from nicosulfuron ranged from 9 to 35% among CYPcyp hybrids and were associated with moderate to severe loss of kernel rows (i.e., ear pinching). Yield of CYPCYP hybrids was not affected by mesotrione or nicosulfuron.