Does doses and time of 2,4-D application interfere in the physiology and wheat grains yield components?

The identification of the application stage and correct dose 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide is important so that wheat not harmed. In view this, objective this study was to evaluate effect 2,4-D doses applied at different development stages crop. experiment conducted in a randomized block design, arranged 4 × 5 factorial scheme, with four replications. factor A, (before tillering, first node booting) were allocated (0, 349, 698, 1047 1396 g.ha–1) B. variables evaluated phytotoxicity 7, 14, 21, 28 35 days after treatments (DAT), photosynthetic activity, CO2 internal concentration, stomatal conductance, efficient water use carboxylation efficiency. number spikes·m–2, spike length full sterile grains determined preharvest. Thousand grain mass, yield hectoliter weight harvest. results demonstrate caused wheat, being greater increasing mainly before causing sterility decreased productivity. other components did present difference when as well physiological variables. increase tillering booting linear decrease yield.