Fungicide applications and grain dry milling quality in late-sown maize

Abstract

Argentinean maize (Zea mays L.) is known for its grain hardness, and exporting grain lots are subject to strict regulations regarding physical characteristics and mycotoxin concentrations. Our production system is changing to later sowings, and the use of foliar fungicides is becoming more common due to positive yield responses. In this study, we evaluated the effects of fungicide treatments at different application timing on specific physical grain quality traits and fumonisins in late-sown maize. For this we used four commercial genotypes differing in grain hardness. Measured traits were yield, individual grain weight, dry milling grain quality attributes (test weight, floaters, vitreousness, and 8-mm screen retention), grain composition (oil, protein, and starch), and total fumonisin concentrations. Yield was affected by genotype and fungicide treatments (p < 0.05). Genotypes differed (p < 0.001) in all grain quality attributes and fumonisin concentrations. Particular genotypes had fumonisin values higher than maximum levels accepted for human consumption (4 μg g−1). Fumonisin concentration differences among genotypes were negatively related to their grain hardness. Fungicide treatments, regardless of type and application timing, increased yield in all genotypes by ~350 kg ha−1. However, fungicides had no significant positive effect on any grain physical quality trait, or on fumonisin concentrations. These results emphasize the importance of genotype selection as a critical crop management option to manage grain physical quality traits and fumonisin contaminations. Fungicides can positively affect yield, but positive effects on dry milling grain quality should not always be expected.