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The increase of organic acids in soils can reduce phosphorus sorption. The objective of the study was to evaluate the competitive sorption of P and citrate in clayey and sandy loam soils, using a stirred-flow system. Three experiments were performed with soil samples (0-20 cm layer) of clayey (RYL-cl) and sandy loam (RYL-sl) Red Yellow Latosols (Oxisols). In the first study, the treatments were arranged in a 2 × 5 factorial design, with two soil types and five combinations of phosphorus and citrate application (only P; P + citrate; and citrate applied 7, 22, 52 min before P); in the second, the treatments were arranged in a 2 × 2 factorial design, corresponding to two soils and two forms of P and citrate application (only citrate and citrate + P); and in the third study, the treatments in a 2 × 2 × 6 factorial design consisted of two soils, two extractors (citrate and water) and six incubation times. In the RYL-cl and RYL-sl, P sorption was highest (44 and 25 % of P application, respectively), in the absence of citrate application. Under citrate application, P sorption was reduced in all treatments. The combined application of citrate and P reduced P sorption to 25.8 % of the initially applied P in RYL-cl and to 16.7 % in RYL-sl, in comparison to P without citrate. Citrate sorption in RYL-cl and RYL-sl was highest in the absence of P application, corresponding to 32.0 and 30.2 % of the citrate applied, respectively. With P application, citrate sorption was reduced to 26.4 and 19.7 % of the initially applied citrate in RYL-cl and RYL-sl, respectively. Phosphorus desorption was greater when citrate was used. Phosphorus desorption with citrate and water was higher in the beginning (until 24 h of incubation of P) in RYL-cl and RYL-sl, indicating a rapid initial phase, followed by a slow release phase. This suggests that according to the contact time of P with the soil colloids, the previously adsorbed P can be released to the soil solution in the presence of competing ligands such as citrate. In conclusion, a soil management with continuous input of organic acids is desirable, in view of their potential to compete for P sorption sites, especially in rather weathered soils.

A Cyperus rotundus é uma planta herbácea perene que se multiplica sexuadamente por semente e assexuadamente por bulbos, tubérculos e rizomas subterrâneos. O objetivo principal desse trabalho foi avaliar o efeito do extrato de Cyperus rotundus no enraizamento de folhas de Solanum lycopersicum. Os estudos foram realizados no laboratório de química e na casa de vegetação, ambos no CCA/Alegre/ES. O experimento foi realizado em duas etapas: a confecção do extrato a partir de 2 g de tiririca em 40 mL de solvente (metanol PA, etanol PA, água destilada), para o teste do extrato no enraizamento empregou-se o delineamento inteiramente casualizado com 17 tratamentos com 6 repetições e 6 plantas por repetição. Dentre os tratamentos, os que promoveram o enraizamento foram os extratos aquosos 100, 50 e 25%, sendo que o extrato aquoso 50% foi o que demonstrou o melhor resultado, se assemelhando ao controle positivo AIB (Ácido indolbutiríco). Os resultados obtidos com o uso do extrato de Cyperus rotundus, parecem ser promissores. Porém são necessários novos estudos, para demonstrar a utilidade prática do extrato Cyperus rotundus no enraizamento.The Cyperus rotundus is an herbaceous perennial plant that multiplies sexually from seed and asexually from bulbs, tubers and underground rhizomes. Thus, the present work aimed to assay the effect of C. rotundus extract on the rhizogenesis of Solanum lycopersicum leaves. The studies were performed in the laboratory of chemistry and greenhouse, at in CCA/Alegre/ES. The extract was prepared from 2g of C. rotundus and 40mL of solvent (methanol PA, ethanol PA and distilled water). The experimental design utilized to test the extract’s effect on rhizogenesis was entirely random, containing 17 treatments, 6 replicates and 6 plants per replicate. The effective treatments were obtained with aqueous extracts at 100, 50 and 25%. However, the best result was observed for the aqueous extract of 50%, similar to the positive control AIB. The results obtained with the use of Cyperus rotundus’ extract, seem to be promising, although further studies are needed to demonstrate the usefulness of Cyperus rotundus’ extract on rhizogenesis.

Biribazeiro é uma planta frutífera da família Annonaceae, nativa da Amazônica e que se desenvolve bem em diferentes habitats. É uma planta que pode atingir altura média de 8 m. Cada nutriente exerce uma função específica na planta, sendo que sua falta pode gerar perdas irreparáveis, podendo levar a planta à morte. O objetivo deste trabalho foi avaliar o desenvolvimento inicial de mudas de biribazeiro submetidas a omissão de macronutrientes em solução nutritiva. Os tratamentos foram: solução nutritiva completa (SNC) = (K; P; Ca; N; Mg; S; Fe; Cu; B; Mo; Mn; Zn); deficiência de potássio (-K) = (SNC-K); deficiência de fósforo (-P) = (SNC-P); deficiência de cálcio (-Ca) = (SNC-Ca); deficiência de nitrogênio (-N) = (SNC-N); deficiência de magnésio (-Mg) = (SNC-Mg); deficiência de enxofre (-S) = (SNC-S). O tratamento com solução nutritiva completa promove maior média para diâmetro do caule. Observa-se redução generalizada na altura e diâmetro do caule nas plantas cultivadas na solução deficiente em nitrogênio. Para todas as características avaliadas, as plantas cultivadas em soluções deficientes em nitrogênio (-N) e cálcio (-Ca) apresentaram sempre os menores valores. Isto demonstra a importância desses nutrientes para o crescimento do biribazeiro.

Mudas do abacaxizeiro ‘Smooth Cayenne’ obtidas por seccionamento de caule foram submetidas à adubação foliar com soluções em diferentes concentrações de uréia, KCl e H3BO3, em pulverizações semanais, num total de vinte e seis para a uréia e o KCl e aplicações mensais num total de quatro, para o H3BO3. Todos os tratamentos foram iniciados na nona semana após o plantio das secções. O delineamento utilizado foi fatorial fracionado do tipo (1/5)53, com três tipos de adubo (uréia, KCl e H3BO3) e cinco concentrações num total de 25 tratamentos. Cada parcela constituiu-se de 50 secções. Os tratamentos consistiram nas combinações das seguintes concentrações em g L-1: 0; 2,5; 5; 7,5 e 10 para a uréia e o KCl, e 0; 0,5; 1; 1,5 e 2,0 de H3BO3. Análises das amostras de folhas “D” revelam efeitos da uréia e H3BO3 sobre os teores foliares de S, Cl e B e efeito do KCL sobre K e Cl foliar. A uréia não apresentou efeito sobre o teor de N foliar, porém influencia significativamente o conteúdo de N nas mudas.‘Smooth Cayenne’ planting material obtained through stem sectioning were trea-ted with foliar fertilization with different concentrations of urea, KCl, in weekly pulverizations, and H3BO4, totalizing twenty-six for urea and KCL pulverizations and four for H3BO3, which was applied monthly The treatments were began nine weeks after planting thestem sections. The experimental scheme was a fractionated factorial (1/5)5³ with three types of fertilizers (urea, KCl and H3BO3) and five concentrations in a total of 25 treatments. There were 50 sections per plot. Treatments were a combination of concentrations in g L-1: 0, 2.5, 5.0, 7.5 and 10 of urea and KCl, and 0, 0.5, 1.0, 1.5 and 2,0 of H3BO3. Sample analyses of ‘D’ leaves showed urea and H3BO3 effect on S, Cl and B leaf contents whereas KCL affected leaf K and Cl contents. Urea did not affect N leaf content, however it strongly influenced N content in planting material.