Physiology and reproductive responses of disease-free soybean plants to triazole, strobilurin, and carboxamide fungicides under greenhouse conditions

Fungicides play a vital role in the economic viability of agricultural crops, and foliar applications have increased substantially in recent decades. However, these compounds may also influence plant metabolism, potentially affecting physiological, reproductive, and productive traits. This study evaluated whether fungicides from the triazole, strobilurin, and carboxamide groups affect physiological and reproductive processes of disease-free soybean plants under controlled greenhouse conditions. Soybean plants (cv. SYN 1378 C) were treated with three commercial fungicides—epoxiconazole +fluxapyroxad+pyraclostrobin (EPZ + FLX+PYR), trifloxystrobin+prothioconazole (TFX + PRZ), and trifloxystrobin+prothioconazole+bixafen (TFX + PRZ+BXF)—and compared with untreated control plants. Applications were performed at R1, R1 + R2, or R1 + R2+R3 in a factorial randomized block design with eight replicates. Overall, most physiological variables were not significantly affected by fungicide treatments. EPZ + FLX+PYR reduced photochemical parameters associated with PSI efficiency, whereas TFX + PRZ and and TFX + PRZ+BXF also reduced pollen germination compared to the control. However, these effects did not translate into significant differences in grain yield. These results suggest that, under greenhouse conditions and in the absence of disease pressure, preventive fungicide applications may alter certain physiological or reproductive traits but do not necessarily affect soybean productivity.