Efeitos da aplicação foliar de benzidrazida sobre as características morfológicas do milho, o perfil de fermentação da silagem e a digestibilidade in vitro

Abstract

Benzohydrazide (BHZ) is a recognized competitive inhibitor of plant peroxidases that can potentially reduce cell wall cross-linking. This study evaluated the effects of foliar BHZ application at the V6 vegetative stage on corn morphological characteristics, silage fermentation profile, and in vitro dry matter digestibility. Corn (hybrid P3889R) was treated with two concentrations of BHZ, 50 μM (BHZ50) and 500 μM (BHZ500), corresponding to field application rates of 1.225 and 12.253 g ha, respectively, using a manual backpack sprayer calibrated for a constant volume of 180 L/ha. Control plants (CON) were sprayed only with dilution vehicle. Plants were harvested at the R5 stage and ensiled in PVC laboratory-scale silos for 102 days. BHZ application did not affect plant height, ear height, fresh matter, or total dry matter yields. The BHZ50 treatment reduced the number of grains per ear compared to CON, whereas BHZ500 did not differ from the CON. No differences were observed in the concentrations of NDF, ADF, lignin, or crude protein. Furthermore, the fermentation profile, including final pH and the concentrations of lactic and acetic acids, was not influenced by the treatments. BHZ500 increased the in vitro dry matter digestibility of the silage by 3.2 percentage points compared to CON. This result was corroborated by a 48-hour ruminal fluid incubation, in which the BHZ500 silage showed a tendency for a 3.0 percentage point increase (69.5% vs. 66.5%). The BHZ50 showed intermediate results. Foliar application of 12.253 g/ha of BHZ at the V6 stage is a low-inclusion technology that enhances the nutritive value of corn silage in subin vitrotropical systems without negative impacts on yield or fermentation profile.