Correlações entre macronutrientes e matéria seca digestível de centrosema (Centrosema pubescens Benth.), siratro (Macroptilium atropurpureum cv. siratro) e soja perene (Glycine wightii Willd.)

Plants of those species were collected from 21 days up to 147 days at 21 days intervals. The material was devided into leaves and stems. Chemical analysis for N, P, K, Ca, Mg and S were run by conventional methods. The dry matter digestibility was obtained in vivo by the nylon bag technique. The correlation coefficients are:Com a finalidade de se detectar correlações entre os teores químicos e a matéria seca digestível em plantas de centrosema, siratro e soja perene, foram cultivadas no campo e coletadas após 21 dias de germinação e em intervalos de 21 dias atÉ a idade de 147 dias. O material coletado foi dividido em folhas e caules e analisados para N, P, K, Ca, Mg e S pelos métodos convencionais, Foram conduzidos testes de digestibilidade in Vivo pela técnica do "saquinho de nylon" em animal fistulado. Foram detectadas correlações positivas para P e Mg e negativas para Ca nas folhas de centrosema. Para o caule da mesma leguminosa foi obtido correlação positiva para P e negativo para o Ca. Nas plantas de siratro somente as folhas apresentam regressão significativa sendo observado correlações positivas para P, K, Ca e negativa para N. Para soja perene K e S apresentam regressão significativa; sendo a correlação positiva para K e negativa para o S

Efeito do sódio na produção de matéria seca em mudas de duas cultivares de algodoeiro mocó (Gossypium hirsutum L., var. Maria Galante Hucth.): cv. '9193' e 'c-71'

A green-house experiment was conducted for 90 days according to a completely randomized block design. The treatments used were as follows: five levels of sodium, 0.0; 4.0; 40.0; 400.0; 4,000 (all in ppm) added as NaCl and Na2SO4, respectively, to a HOAGLAND & ARNON complete nutrient solution. These were used individually as nutrient media for two cotton plant cultivars, namely '9193' and 'c-71', thus comprising a total of 20 treatments wich were replicated four times each. The results showed an increase in dry matter production of the plants as a result of the addition of 4.0 ppm of sodium whereas 400.0 ppm and 4,000 ppm had a decreasing effect. The drymatter production of the cultivar '9193' interacted negatively with the chloride íon.Durante um período de noventa dias, foi conduzido em casa de vegetação, um experimento inteiramente casualizado, com quatro repetições. Foram testados cinco níveis de sódio (0; 4; 40; 400; 4.000 ppm de sódio) utilizando-se duas fontes, cloreto e sulfato de sódio e duas cultivares de algodoeiro mocó (G. hirsutum, var. Maria Galante, Hucth.) !9193' e 'c-71', cultivadas em solução nutritiva. Os resultados mostraram que a dose 4 ppm de sódio provocou aumento na produção de matéria seca do algodoeiro, enquanto as doses 400 e 4.000 ppm de sódio, provocaram diminuição. Ocorreu efeito negativo na produção de materia seca da cultivar '9193' provocado pelo cloreto

Efeitos da nutrição mineral sobre o crescimento, aspecto, composição elementar e fixação de nitrogênio em Azolla

The mineral nutrition of Azolla feliculoides Lam was studied in solutions deficient in phosphorus, potassium, calcium, magnesium, sulfur, iron and molybdenum, and in excess of Mn and Al. Dry weight, N2 fixation and mineral composition of Azolla were determined after 3 weeks. Phosphorus, potassium, calcium and magnesium deficiencies and excess of manganese and aluminium decressed growth severely and also depressed the activity of nitrogenase. Phosphorus deficiency improved the uptake of iron and zinc. Potassium deficiency increased the levels of phosphorus in dry matter. Magnesium deficiency caused lower uptake of K and better uptake of Ca, Fe and Mn. Sulfur deficiency reduced aluminium uptake and promoted the best growth. Positive correlations were found between: N content and dry matter, nitrogenase activity and N content.Azolla filiculoides Lam foi cultivado em solução nutritiva arejada, sempre desprovida de N combinado, sendo submetida aos seguintes tratamentos: omissão de P, K, Ca, Mg, S, Fe e Mo, excesso de Mn e Al. As plantas foram colhidas depois de 3 semanas da inoculação. Verificou-se que as deficiências de P, K, Ca e Mg provocaram diminuição na produção de matéria seca e na atividade de nitrogenase. A análise mineral mostrou que: a falta de um elemento provoca redução no seu teor; grande acumulo de Mo; diminuição no teor de Al (do inóculo ou contaminação) no tratamento menos S que garantiu o maior crescimento; efeitos inibitórios ou sinergísticos semelhantes aos descritos no caso de plantas superiores. A toxidez de Al e Mn causou, principalmente a primeira, redução no crescimento e na atividade da nitrogenase. Houve correlações positivas entre: N total e crescimento, atividade de nitrogenase e N total

Quantification of the biomass and nutrients in the trunk of Eucalyptus grandis at different ages

The accumulation and cycling of nutrients in planted forest is essential to the establishment of management practices that can lead to the sustainable production of the forest site. The uptake, accumulation and release of nutrients depend on tree age and stage of development. The knowledge of accumulation and cycling of nutrients allows the estimation of output and replacement of nutrients to the forest site. This makes it possible to correct nutritional disorders caused by the use of inadequate management techniques. The usual method of sampling biomass and nutrients is always destructive making it impossible to establish permanent plots for nutritional monitoring. This study aimed at selecting models to estimate the biomass (volume and weight) and the nutrient contents in different parts of the trunk of Eucalyptus grandis, and reducing costs of sampling and analysis. Forty-five trees were selected from the dominant class (15 trees), co-dominant (15 trees) and suppressed (15 trees) in commercial plantations of E.grandis at ages 3, 5 and 7 years, in the municipality of Itatinga, SP, Brazil. Samples were taken of bark, sapwood and heartwood separately. Models to estimate volume and weight in the different components of the trunk were generated from the diameter at breast height (dbh) using regression analysis. Models to estimate content of N, P, K, Ca and Mg in the bark, sapwood and heartwood from the nutrient contents in a section of the trunk were also defined, so enabling a recommendation for non-destructive sampling

Site characterisation and the effects of harvesting on soil tillage on the productivity of Eucalyptus grandis plantations in Brazil

Two commercial eucalypt sites were selected in Sao Paulo State, Brazil, to evaluate productivity and soil chemical and physical properties before clearcutting, and the effect of harvesting and soil tillage system on productivity of second rotation. At site 1, the Eucalyptus grandis plantation was 7 years old, on its first rotation, and reached 21 m mean height, 13.6 cm diameter breast height (dbh), an estimated commercial volume of 479 m3 ha-1 and a mean annual increment of 68 m3 ha-1 year-1. At site 2, E. grandis, also on its first rotation, but 12-years-old, had 25 m mean height, dbh 16 cm, an estimated volume of 662 m3 ha-1 and a mean annual increment of 55 m3 ha-1 year-1. Litter collected at site 2 before harvesting totalled 19.8 t ha-1, and after harvesting and new planting, litter left on surface totalled 2.64 t ha-1. At site 1, 31.3 t ha-1 of litter accumulated before harvesting and 7.6 t ha-1 after new planting. Soils of both sites are classified as Dark Red Latosol (Oxisol), having loam texture at site 2 and clay texture at site 1. Clay content difference between sites was around 10 %, available soil water content between sites varied less than 0.02 cm3 cm-3. Penetrometer soil resistance measured before harvesting and after new planting was less than 21 kg cm-2, at 50 cm besides tree row, on both sites. Greater soil resistance measured at tree row was found at 15-cm depth, in both sites. Soil of site 1 has greater CEC, base saturation and organic matter content compared to site 2. One year after planting eucalypts growing on soil tilled with subsoiler with one shrank were smaller at site 2

Nutrient export by clear cutting Eucalyptus grandis of different ages on two sites in Brazil

At two sites, where Eucalyptus grandis plantations were 7 and 12 years old, twelve dominant trees were cut and measured. The 12-year-old-trees were 29.4 m mean height, 19.9 cm diameter over bark and estimated volume 0.40 m3 tree-1. The 7 year-old trees were 30.7 m mean height, 20.6 cm diameter and estimated volume 0.49 m3 tree-1. Of total biomass, 92% was trunk (sapwood, heartwood and bark). Based on a population of 1500 trees ha-1, there is an export of biomass of 296 t ha-1 from 302 t ha-1 being produced, when the entire trunk is removed. When only commercial stems are removed, there is an export of 277 t ha-1. Within a whole tree, N is the nutrient present in greatest amount, followed by K, Ca, Mg and P. When parts of the tree are analysed, calcium is the nutrient present in greatest amount in bark. Phosphorus was not detected by the chemical analysis in heartwood in trees of 12 years of age, but it was present in trees aged 7 years. The amount of N and K extracted from soil by the trees is greater than the amount of these nutrients supplied by fertiliser, usually around 20 g plant-1 of N and 15 g plant-1of K2O. More than 50% of N, Ca and Mg are in the heartwood, sapwood and bark. Even if only commercial stems are taken from the plantation area, most of the nutrients will be exported