Do fungicides affect the physiology, reproductive development and productivity of healthy soybean plants?

Fungicides are widely used to control diseases in soybean crops. We hypothesized that fungicides applied to healthy soybean plants compromise the plant's physiology, affect the reproductive process and reduce crop productivity. We aimed to evaluate the photosynthetic process, pollen grain viability and yield components of soybean plants exposed to three commercial fungicides. The experiment was performed twice using soybean cultivar SYN 1378C, disease-free plants, with four treatments: i) control treatment (without any fungicide application); ii) cyproconazole 150 g L + difenoconazole 250 g L (CPZ + DFZ; 250 mL ha; without adjuvant); iii) azoxystrobin 300 g Kg + benzovindiflupyr 150 g Kg (AZB + BZP; 200 g ha; Nimbus® adjuvant (Syngenta)); and iv) propiconazole 250 g L + difenoconazole 250 g L (PPZ + DFZ; 150 mL ha; without adjuvant) in both soybean pre-bloom (V8) and bloom (R1) developmental stages. The experimental design was randomized blocks with four replicates. Phytotoxicity, gas exchange and chlorophyll a fluorescence traits, pollen grain viability, pollen grain germination, flower abortion and soybean production components were evaluated. The fungicides did not affect the physiological traits, pollen grain germination and crop yield.