Understanding the mechanisms of absorption and transport of foliar nutrition is a key step towards the development of advanced fertilization methods. This study employed X-ray fluorescence (XRF) and X-ray absorption near edge spectroscopy (XANES) to trace the in vivo absorption and transport of ZnO and ZnSO4(aq) to soybean leaves (Glycine max). XRF maps monitored over 48 h showed a shape change of the dried ZnSO4(aq) droplet, indicating Zn2+ absorption. Conversely, these maps did not show short movement of Zn from ZnO. XRF measurements on petioles of leaves that received Zn2+ treatments clarified that the Zn absorption and transport in the form of ZnSO4(aq) was faster that of ZnO. Solubility was the major factor driving ZnSO4(aq) absorption. XANES speciation showed that in planta Zn is transported coordinated with organic acids. Because plants demand Zn during their entire lifecycle, the utilization of sources with different solubilities can increase Zn use efficiency.

Increasing the yield of soybean is a challenge to humankind dependent on several management practices, such as fertilizing and weed control. While glyphosate contributes to controlling weeds, it can interfere with spray mixture stability and, supposedly, complex with micronutrients within the plant tissue. This study investigated the effects of glyphosate on soybean foliar uptake and transport of Mn supplied as MnSO4, MnHPO3, Mn-ethylenediamine tetraacetic acid (EDTA), and MnCO3. These fertilizers induced ultrastructural changes in the leaf cuticle, regardless of the glyphosate mixture. Except for MnCO3, all tested sources increased the Mn content in the petiole. The mixture of glyphosate impaired Mn transport from MnSO4 and MnHPO3, but no evidence of Mn–glyphosate complexation within the plant was found. Manganese is rather transported in a similar chemical environment regardless of the source, except for Mn-EDTA, which was absorbed and transported in its pristine form. Interferences of glyphosate seem to be related to complexations in the tank mixture rather than affecting nutrients’ metabolism.

No abstract

Avaliou-se o desenvolvimento fenológico de frutos da lichieira em duas regiões diferentes do Brasil, sendo uma em Casa Branca-SP e outra em Monte Belo-MG. As avaliações foram realizadas quinzenalmente, tendo início a partir do vingamento dos frutos e seguindo até o ponto de maturação fisiológica dos respectivos locais. Foram realizadas as seguintes avaliações: número de frutos por inflorescência, diâmetro longitudinal e transversal, matéria fresca e seca dos frutos, teor de sólidos solúveis e acidez titulável dos frutos. A abscisão dos frutos em Casa Branca foi constante até 28 dias do vingamento, com perda de aproximadamente 46% dos frutos. Em Monte Belo a perda foi constante durante todo o período de avaliação, sem que houvesse estabilização deste parâmetro. A acumulação de matéria seca no início das avaliações foi lenta em ambos os locais, passando a acelerar respectivamente após os 28 e 27 dias do vingamento. No ponto de maturação fisiológica, as plantas de Casa Branca apresentaram um número médio de 10 frutos por inflorescência a mais do que as plantas de Monte Belo. Em ambos os locais, os frutos levaram cerca de 12 semanas após o vingamento para chegarem ao estádio de maturação fisiológica.