02830nam a2200181 a 450000100080000000500110000800800410001910000220006024500580008226000160014030000100015650001020016652023040026865000210257265000220259365300180261565300150263320543872016-10-11       2016    bl uuuu  m   00u1 u    #d1 aSANTOS, L. R. dos  aBrassinosteroids mitigate cadmium toxicity in cowpea.  a2016.c2016  a56 f.  aDissertation (Magister Scientiae Degree in Agronomy) - Universidade Federal do Pará, Belém, PA.  aAnthropogenic activities as inadequate uses of phosphate fertilizers have been increased the cadmium concentrations in agricultural soils. Brassinosteroids are natural substances of fast assimilation and metabolism, which it plays beneficial roles in physiological and biochemical processes in plants. The objective went determinate the EBR contributions on nutrient concentrations, chlorophyll fluorescence, gas exchange, oxidant compounds, cell damages, pigments and growth,, as well as responds what better EBR concentration to be indicated in Vigna unguiculata plants exposed to Cd toxicity. The experimental design employed was entirely randomised, with two cadmium levels (0 and 500 µM Cd) and three brassinosteroids levels (0, 50 and 100 nM EBR), in a factorial 2x3. The EBR splay caused significant reductions in Cd concentrations of all tissues. Nutrient concentrations were increased by the EBR application, being verified increases to Mn (82.2%) and Fe (41.2%) in stem, as well as Cu (125%) and Zn (95.8%) in leaf, when compared with compared to 0 nM EBR + 500 ?M Cd. In relation to chlorophyll fluorescence, EBR provoked also had beneficial responses, increasing ?F/Fm?, qP and ETR, reducing NPQ, EXC and ETR/PN in plants with and without Cd toxicity. Foliar application of EBR reduced the negative effects due to Cd toxicity on gas exchanges, being detected increases of 74%, 67% and 100% to PN, WUE and PN/Ci, comparison with 0 nM EBR + 500 ?M Cd, respectively. The Cd promoted increased O2-, H2O2, MDA and EL levels, but EBR caused significant decreases in these variables, when compared to control exposed to Cd. In pigments, the pre-treated with EBR and exposed to Cd presented increases in CHL a, CHL b, total CHL, and CAR, compared the same treatments without EBR. To growth, the EBR induced significant increases of 26.2, 20.4 and 21% in the leaf, root, and plant, respectively. The results confirm the hypothesis that EBR attenuates the negative impacts promoted by the Cd toxicity on nutrient concentrations, chlorophyll fluorescence, gas exchange, pigments and growth due to reductions in absorption and transport of Cd, lower production of oxidant compounds and reduction in cell damages of cowpea plants, which can be indicated the concentration of 100 nM EBR to this crop.  aFeijão de Corda  aVigna Unguiculata  aFeijão caupi  aToxicidade