Marialva Alvarenga Moreira

Interação zinco e fósforo em solução nutritiva influenciando o crescimento e a produtividade da alface

Zinc and phosphorus interaction in nutrient solution affecting lettuce growth and yield Abstract†n†The experiment was carried out to evaluate the effect of Zn and P levels in nutrient solution on Zn and P absorption and lettuce yield (Lactuca sativa†L.). A†randomized block experimental design in 3†x†3 factorial arrangement with three replications was used. The treatments were three Zn levels: low, normal and high, corresponding to 0.0, 1.5 and 6.0†mM†L -1 and three P levels: low, normal and high, corresponding to 0.01, 1.5 and 6.0†mM†L -1 as ZnSO4.7H2O and KH2PO4. Twenty six days after transplantation (DAT), the leaf area and leaf dry weight were not influenced by the treatments. At 52†DAT, the leaf area, the leaf number and the shoot dry weight were not affected by Zn addition when the P level was low; but when P levels were normal and high, the normal and high Zn levels lead to the highest leaf area, leaf number, and shoot dry weight. Phosphorus concentrations in the marketable leaves at each Zn level were similar at P normal and high addition levels. The highest P concentration was observed in the stem followed by roots and marketable leaves. Zinc concentrations in the market- able leaves, stem and roots, increased with Zn addition to the nutrient solution.

Production of basic potato seed minitubers in substrate and different nitrogen rates

A dose otima de nitrogenio (N) na cultura da batata depende do sistema de producao. O objetivo deste trabalho foi determinar a dose otima de N para a producao de minituberculos de batata-semente basica e avaliar o efeito de doses de N sobre indices nitrogenados e fisiologicos determinados na folha mais jovem completamente desenvolvida (quarta folha) e na folha mais velha da planta, aos 60 dias apos o plantio. O experimento foi realizado em ambiente protegido, no Departamento de Fitotecnia da Universidade Federal de Vicosa. Os tratamentos foram constituidos por cinco doses de N (0, 45, 90, 180 e 360 mg dm-3), sendo 10% de cada dose aplicada em pre-plantio e o restante via agua de irrigacao, diariamente, por 30 dias. As doses de N influenciaram positivamente os indices fisiologicos (comprimento, largura, area foliar, numero de foliolos, massas de materias fresca e seca) e nitrogenados (teor e conteudo de N e N-NO3 na materia seca e indice SPAD) tanto na quarta folha quanto na folha velha. Da mesma forma, doses de N influenciaram positivamente o numero e a massa de tuberculos colhidos. O maior numero (5,44 tuberculos/planta) e a maxima massa de tuberculos (243,5 g/planta) foram obtidos com 360,0 e 332,9 mg dm-3 de N, respectivamente. Portanto, numero e massa de tuberculos nao foram otimizados pela mesma dose de N. O indice critico SPAD na quarta folha foi 38,8, sendo essa mais sensivel ao efeito de doses de N do que a folha mais velha.

Produção de minitubérculos de batata semente básica em hidroponia em função de doses de nitrogênio

A dose otima de nitrogenio (N) na cultura da batata depende do sistema de producao. O objetivo do trabalho foi determinar a dose otima de N para a producao de minituberculos de batata-semente basica em hidroponia e verificar o desenvolvimento da planta no sistema hidroponico em plataforma de telha amianto. O experimento foi realizado em ambiente protegido, no Departamento de Fitotecnia da Universidade Federal de Vicosa, utilizando o plantio de broto da cultivar Asterix. Os tratamentos foram constituidos por quatro doses de N (45; 90; 180 e 270 mg L-1), sendo 10% de cada dose de N aplicadas na forma de nitrato de amonio (N-NH4+) e o restante de N na forma de nitrato de calcio e nitrato de potassio. O maior numero (14,1 tuberculos/planta) e a maxima massa de tuberculos (68,4 g/planta) foram obtidos com 188,9 e 270 mg L-1 de N, respectivamente. Portanto, numero e massa de tuberculos nao foram otimizados pela mesma dose de N. O indice critico SPAD na quarta folha e variavel com a idade da planta sendo de 38,4 o maior valor atingido aos 58 DAT.

Characterization of the effects of macronutrient deficiencies in mangabeira seedlings

Knowledge of the mineral nutrition requirements of mangabeira (Hancornia speciosa Gomes) is relatively scarce and rudimentary because there is a lack of consistent data concerning its nutritional demands at different developmental stages. The aim of this research was to characterize the visual symptoms of macronutrient deficiencies and to evaluate the effects of these deficiencies on the growth, the production of dry matter, and the leaf content of mangabeira. To achieve this goal, a greenhouse experiment was conducted at the Goiano Federal Institute (Instituto Federal Goiano) in Rio Verde - GO, from January to June 2011 in which mangabeira plants were arranged in a random block design and grown in nutrient solutions. This experiment was replicated four times. The plants were treated with either a complete nutrient solution or a nutrient solution from which the individual macronutrient of interest (nitrogen (N), phosphorous (P), potassium (K), magnesium (Mg), calcium (Ca), or sulfur (S) had been omitted. The omission of a macronutrient from the nutrient solution resulted in morphological alterations that were characteristic symptoms of the particular nutritional deficiency and caused decreases in growth and dry matter mass production. The accumulation of macronutrients displayed the following order in mangabeira leaves: N>K>Ca>P>S>Mg.

Morphoanatomical characteristics of leaves of Anacardium othonianum seedlings subjected to different nitrogen doses under hydroponic conditions

Nitrogen is an essential nutrient that plants generally require in large amounts. Knowing the nitrogen dose that stimulates primary and secondary metabolic pathways is important for the management of nitrogen fertilisation in plants in general; however, this information is still unavailable for seedlings of the cerrado cashew tree. Based on the hypothesis that the availability of nitrogen for Anacardium othonianum Rizz. seedlings can affect can affect the development of anatomical structures, as well as the synthesis of secondary metabolism compounds in leaves, an experiment was conducted to determine the qualitative and quantitative anatomy this tissue collected from plants of this species subjected to N doses of 0, 2.5, 5.0, 7.5, 10.0, 12.5, and 15.0 mmol L−1 in nutrient solution and evaluated the effect at 30 and 90 days after transplanting (DAT). The largest leaf morphoanatomical changes were observed under the doses of 0 and 15.0 mmol L−1 of N. The lowest stomatal density being observed in the plants exposed to an N dose of 15 mmol L−1. The level of flavonoids was not influenced by the availability of N in the solution; however, the absence of nitrogen directly affected the accumulation of phenolic compounds, alkaloids and polysaccharides present in the leaves, whereas the doses of 7.5, 10.0 and 12.5 mmol L−1 were essential to stimulate the presence of this latter compound in cerrado-cashew-tree seedlings maintained in nutrient solution. Regarding the epochs of evaluation, effect was observed only for the thickness of the adaxial epidermis. These data confirm the hypothesis that the leaf anatomy as well as the accumulation of secondary metabolism compounds in leaves of A. ohonianum can be modified because of the availability of N to the plant.

Characterization of nutrient deficiency in Hancornia speciosa Gomes seedlings by omitting micronutrients from the nutrient solution

Hancornia speciosa Gomes (Mangaba tree) is a fruit tree belonging to the Apocynaceae family and is native to Brazil. The production of seedlings of this species is limited by a lack of technical and nutritional expertise. To address this deficiency, this study aimed to characterize the visual symptoms of micronutrient deficiency and to assess growth and leaf nutrient accumulation in H. speciosa seedlings supplied with nutrient solutions that lack individual micronutrients. H. speciosa plants were grown in nutrient solution in a greenhouse according to a randomized block design, with four replicates. The treatments consisted of a group receiving complete nutrient solution and groups treated with a nutrient solution lacking one of the following micronutrients: boron (B), copper (Cu), iron (Fe), manganese (Mn), zinc (Zn), and molybdenum (Mo). The visual symptoms of nutrient deficiency were generally easy to characterize. Dry matter production was affected by the omission of micronutrients, and the treatment lacking Fe most limited the stem length, stem diameter, root length, and number of leaves in H. speciosa seedlings as well as the dry weight of leaves, the total dry weight, and the relative growth in H. speciosa plants. The micronutrient contents of H. speciosa leaves from plants receiving the complete nutrient solution treatment were, in decreasing order, Fe>Mn>Cu>Zn>B.