Genetic variation for response to mixed triazole and strobilurin application in diverse maize

Authors: WOORE, MATTHEW - North Carolina State University; Holland, Jim - Jim

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2020
Publication Date: 5/29/2020
Citation: Woore, M., Holland, J.B. 2020. Genetic variation for response to mixed triazole and strobilurin application in diverse maize. Agrosystems, Geosciences & Environment. https://doi.org/10.1002/agg2.20054.
DOI: https://doi.org/10.1002/agg2.20054

Interpretive Summary: Certain fungicides have been reported to increase corn yield when applied even in the absence of disease. These are referred to as growth regulator effects of the fungicides. We tested the hypothesis that there is genetic variation among maize varieties for response to growth regulator, with the goal of determining if it would be possible to breed for high response to growth regulator as a way to increase corn yield. Our results indicate no measurable effect of growth regulator on corn yield averaged across varieties, and no significant genetic variation for yield response to growth regulator. These results were observed within a very diverse sample of maize hybrids, and also within a very diverse sample of maize inbreds. Therefore, our results suggest that breeding for high response to growth regulator in corn is unlikely to be effective.

Technical Abstract: Strobilurin and triazole classes of fungicides have growth regulating effects on crop plants. When applied to maize in the field, the growth regulating effects of these fungicides are sometimes associated with increases in yield. Because the response of maize plants to these growth regulators is not uniform across genotypes, it may be possible to breed selectively for high rates of yield increases due to growth regulator response. To test this hypothesis, diverse samples of maize inbred lines and hybrids were evaluated for response to a combined strobilurin and triazole fungicide. Main effects of growth regulator treatment and genotype and treatment by genotype interactions were measured on agronomic traits including grain yield and several yield components, lodging, and delayed leaf senescence. Hybrid and inbred genotype main effect variation was significant for all measured traits. Favorable main effects of growth regulator were observed only for leaf senescence and foliar disease, and genotype-treatment interactions were not significant for yield or yield components. Yield was significantly increased only in two inbred varieties and did not correlate with any known pedigree or genetic relationships. These results suggest that breeding to enhance the response to strobilurin and triazole treatment is not likely to be effective in maize.