Carbonate-silicate ratio for soil correction and influence on nutrition, biomass production and quality of palisade grass

Silicates can be used as soil correctives, with the advantage of being a source of silicon, a beneficial element to the grasses. However, high concentrations of silicon in the plant would affect the digestibility of the forage. To evaluate the influence of the substitution of the calcium carbonate by calcium silicate on the nutrition, biomass production and the feed quality of the palisade grass [Urochloa brizantha (C. Hochstetter ex A. Rich.) R. Webster], three greenhouse experiments were conducted in completely randomized designs with four replications. Experimental units (pots) contained a clayey dystrophic Rhodic Haplustox, a sandy clay loam dystrophic Typic Haplustox and a sandy loam dystrophic Typic Haplustox. Each soil received substitution proportions (0, 25, 50, 75 and 100 %) of the carbonate by calcium silicate. The increase in the proportion of calcium silicate elevated the concentrations and accumulations of Si, Ca, Mg, and B, reduced Zn and did not alter P in the shoot of plants. The effects of the treatments on the other nutrients were influenced by the soil type. Inclusion of calcium silicate also increased the relative nutritional value and the digestibility and ingestion of the forage, while the concentration and accumulation of crude protein and the neutral detergent and acid detergent fibers decreased. Biomass production and feed quality of the palisade grass were generally higher with the 50 % calcium silicate treatment

TYPES OF STEM CUTTINGS AND ENVIRONMENTS ON THE GROWTH OF COFFEE STEM SHOOTS

Buscando a adequação de uma metodologia para produção de mudas de Coffea arabica L. via propagação vegetativa, objetivou-se avaliar neste trabalho o efeito de diferentes tipos de estacas caulinares utilizadas para a formação de mudas de café arábica. O experimento foi instalado em delineamento inteiramente casualizado, disposto em esquema fatorial 3 x 2, correspondentes a três tipos de segmentos (herbáceos, semilenhosos e lenhosos) e dois ambientes (telado de sombrite e casa de vegetação). O experimento foi conduzido por 90 dias. No encerramento foram avaliadas as seguintes variáveis: altura da planta, número de nós, número de pares de folhas, comprimento da raiz principal e a matéria seca da planta. Através dos resultados observa-se que a estaca semilenhosa apresentou a maior média para comprimento da raiz principal, diferindo significativamente dos outros segmentos. Para matéria seca da planta, as estacas semilenhosa e lenhosa não diferiram entre si significativamente, mas foram superiores as herbáceas. O telado de sombrite destacou-se como o melhor local para condução dessas mudas.Looking to contribute to the formation of an appropriate methodology for Coffea arabica L. stem shoots production through vegetative propagation, this work aimed to evaluate the effect of different types of stem cuttings used for the formation of Arabic coffee stem shoots obtained from stem cuttings, under two different environments. The experiment was carried out in an completely random design, in a 3 x 2 factorial experiment, corresponding to three types of segments (herbaceous, semi-woody and woody) and two environments (shaded nursery and greenhouse). The experiment was conducted for 90 days. At conclusion the following variables were evaluated: plant height, number of nodes, number of leaf pairs, length of the principal root and the plant dry matter. It was observed that for the longest root of the semi-woody cutting presented the highest average, differing significantly from the other cuttings. For total dry matter, the semi-woody and woody cuttings did not present significant difference amongst themselves, but they were superior to the herbaceous cuttings. The shaded nursery stood out as the best local for the development of these seedlings

Selenium behavior in the soil environment and its implication for human health

ABSTRACT Selenium (Se) is an important element that was discovered in 1817, and since the 1960s, it has been regarded as an essential micronutrient for both animals and humans, playing among other functions a relevant role in the antioxidant system of mammals. Inadequate blood Se levels in the human body is a well-known concern in many parts of the world. This malnutrition problem is often due to Se-poor diet, probably as a result of the low Se availability in soils where crops are growing. Nowadays, it is known that not only the total content, but also the inorganic and organic forms of Se contained in foods are important for human nutrition. However, paradoxically some regions of the world present high Se levels in soils causing several functional disorders and diseases in people who live in seleniferous areas. As essential micronutrient, Se should be supplied in controlled amounts to avoid harmful effects. Therefore, taking into account the importance of the soils as a way to ensure the adequate Se supply for the population, this review has dealt with Se behavior in soil environment (e.g., Se forms and adsorption and desorption reactions) and its relevance for the human health. As a final message, the further understanding of Se behavior in soils to predict its availability for crops in different systems will be a significant approach in future studies to establish forms and safe doses of Se to be added in fertilizers. Agronomic and genetic biofortification of staple crops with Se has been suggested as an important tool to improve Se intake by population in Se-poor sites

Selenium behavior in the soil environment and its implication for human health

<div><p>ABSTRACT Selenium (Se) is an important element that was discovered in 1817, and since the 1960s, it has been regarded as an essential micronutrient for both animals and humans, playing among other functions a relevant role in the antioxidant system of mammals. Inadequate blood Se levels in the human body is a well-known concern in many parts of the world. This malnutrition problem is often due to Se-poor diet, probably as a result of the low Se availability in soils where crops are growing. Nowadays, it is known that not only the total content, but also the inorganic and organic forms of Se contained in foods are important for human nutrition. However, paradoxically some regions of the world present high Se levels in soils causing several functional disorders and diseases in people who live in seleniferous areas. As essential micronutrient, Se should be supplied in controlled amounts to avoid harmful effects. Therefore, taking into account the importance of the soils as a way to ensure the adequate Se supply for the population, this review has dealt with Se behavior in soil environment (e.g., Se forms and adsorption and desorption reactions) and its relevance for the human health. As a final message, the further understanding of Se behavior in soils to predict its availability for crops in different systems will be a significant approach in future studies to establish forms and safe doses of Se to be added in fertilizers. Agronomic and genetic biofortification of staple crops with Se has been suggested as an important tool to improve Se intake by population in Se-poor sites.</p></div

Interação fosfito e fosfato no crescimento e na nutrição fosfatada do feijoeiro em solução nutritiva

O uso de fosfito como fungicida ou como fonte suplementar de fósforo (P) tem se intensificado nos últimos anos; entretanto, pouco se sabe sobre seus efeitos em culturas importantes como o feijoeiro. Objetivou-se com este trabalho avaliar o efeito da interação entre fosfito e fosfato sobre o crescimento e a nutrição fosfatada do feijoeiro. Dois experimentos foram realizados, em delineamento inteiramente casualizado em solução nutritiva, em casa de vegetação, no período de janeiro a março de 2008. No primeiro, os tratamentos foram constituídos por um esquema fatorial 5 x 2, sendo cinco concentrações de P na solução nutritiva: 0,5; 10; 20; 30; e 60 mg L-1 e duas formas de P: fosfito (Phi) e fosfato (Pi), com quatro repetições. No segundo experimento, os tratamentos foram constituídos por cinco proporções de Pi:Phi em solução nutritiva: 100:0, 75:25, 50:50, 25:75 e 0:100, com cinco repetições. Os resultados evidenciaram que as plantas cultivadas com fosfito como única forma de P, ou em elevadas proporções de Phi, apresentaram redução acentuada na matéria seca da parte aérea e de raízes, refletindo em valores desprezíveis para o acúmulo de P nesses tecidos. Da mesma forma, a atividade da enzima fosfatase ácida apresentou decréscimo com o aumento das proporções de Phi, enquanto os teores de Pi solúveis diminuíram. Concluiu-se que o fosfito não é capaz de substituir o fosfato na nutrição fosfatada do feijoeiro, tendo efeito nulo sobre o feijoeiro sob adequada disponibilidade de fosfato. Na ausência ou baixa disponibilidade de fosfato, ocorre toxicidade acentuada de fosfito no feijoeiro que se apresentou muito sensível a esse ânion

Growth and accumulation of phosphorus by bean plants treated with foliar phosphate and phosphite

Currently the use of phosphite as fungicide in agriculture or as a supplementary source of phosphorus (P) has been widespread, however little is known about its effects on phosphate nutrition of important crops such as bean plants. The present work aimed to evaluate the effect of foliar applied phosphite and phosphate on the growth and phosphated nutrition of the bean plant cultivated under low and adequate P supply conditions. The experiment was conducted in an entirely random layout, in factorial scheme 2 x 3 x 2, where two phosphate concentrations were combined in the nutrient solution (1.5 mg L-1 = low phosphorous and 20 mg L-1 = adequate phosphorous), three foliar application products: KH2PO3 (monobasic potassium phosphite), KH2PO4 (monobasic potassium phosphate) and KCl (potassium chloride) as control and two treatments referring to the number of applications (one application, at the appearance of the first trifoliolate leaf and two applications: one at the appearance of the first trifoliolate leaf and the other application at the pre-flowering), with four repetitions. Overall the dry matter, fosfatase activity, phosphorus content and phosphorus use efficiency was not were affected by the foliar application treatments. Under low readiness of that nutritient the application of foliar phosphite had a negative effect on these variables. It was concluded that foliar applied phosphite has a depressive effect on the growth of the bean plant under low supply of P. The foliar phosphite slightly affects the total concentration of P in the roots and shoots, especially under low P supply, and provides no changes in levels of soluble fractions of P in leaves under conditions of low or adequate supply this nutrient

Interação entre silício e nitrogênio em arroz cultivado sob solução nutritiva Silicon-nitrogen interaction in rice cultivated under nutrient solution

O presente estudo objetivou avaliar o efeito da interação entre silício e nitrogênio nos teores de clorofila, nitrato, amônio e nitrogênio total, na produção de biomassa e nos números de perfilhos e de panículas em arroz cultivado em solução nutritiva. Utilizou-se o delineamento inteiramente casualizado em esquema fatorial 5 x 2, sendo duas concentrações de silício (0 e 50 mg L-1) e cinco as de nitrogênio (20; 50; 100; 200 e 400 mg L-1), com três repetições. No estádio de formação do colar da folha bandeira foram realizadas a leitura SPAD e as determinações dos teores de clorofila a e b, nitrogênio nítrico, amoniacal e total. No estádio de maturidade completa da panícula, foram avaliados os números de perfilhos e de panículas e determinaram-se os pesos de matéria seca de raiz e parte aérea e o acúmulo de silício na planta. Os resultados mostraram que o fornecimento de silício não alterou o perfilhamento, a produção de matéria seca e os teores de nitrogênio total. O silício elevou os valores SPAD, os teores de clorofila a e b, os teores de nitrato nas raízes e o número de panículas, especialmente em doses elevadas de nitrogênio.<br>The present study aimed to evaluate the interaction effect between silicon and nitrogen in the content of chlorophyll, nitrate, ammonium and total nitrogen, dry matter production, number of tillers and number of panicles rice-plant cultivated in nutritional solution. A factorial design 5 x 2 trial installed in a completely randomized design was used being two silicon (0 and 50mg L-1) and five nitrogen (20; 50; l00; 200 and 400 mg L-1) concentrations. In the stadium of the flag leaf collar formation SPDA reading and the a and b chlorophyll contents, ammoniacal and total nitrogen determinations in plants were detemined. During the panicle complete maturity stadium, the number of tillers and panicles were evaluated and the aerial part and root dry matter contents and silicon accumulation were determined. The outcomes show that the silicon supply did not change the tillering, the dry matter production and total nitrogen contents. The silicon increased the SPAD values, the a and b chlorophyll and the root nitrate contents, and the number of panicles, especially at high nitrogen levels