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

Abstract

Strobilurin and triazole classes of fungicides have been reported to have growth‐regulating effects on crops in the absence of their target pathogens and to increase maize yield. Because the response of maize (Zea mays L.) plants to a commercially marketed mixture of strobilurin and triazole may not be uniform across genotypes, it may be possible to breed selectively for higher yield responses to application of this chemical treatment. To test this hypothesis, diverse samples of maize inbred lines and hybrids were evaluated for response to a combined mixture of a treatment of strobilurin and triazole. Main effects of treatment and genotype and treatment × 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 strobilurin and triazole treatment 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.