Suchergebnisse

Cationic micronutrients bioavailability depends on the chemical characteristics of soil fractions. Fourteen soils received individual doses of five micronutrients (Cu, Fe, Mn, Zn, B) arranged in seven treatments set according a Baconian Matrix. The soils incubated with treatments during 15 days had corn cultivated in greenhouse for 30 days, in three consecutive growth cycles. The cationic micronutrients were determined in the corn shoots after each growth cycle. Soil samples collected before the first and after each growth cycle had the available concentrations of Cu, Fe, Mn and Zn determined by single extractions (Mehlich-1 and DTPA-pH 7.3) and by sequential extraction. Correlation analysis was performed for the Cu, Fe, Mn and Zn concentrations determined in the corn shoots, the available concentrations of Cu, Fe, Mn and Zn in the soils (Mehlich-1 and DTPA) and the concentrations of Cu, Fe, Mn and Zn in the soil fractions (sequential extraction). The distribution of available metals forms in fractions reflected their affinity with soil components. Soil available Cu correlated with Cu bound to organic matter. The exchangeable fraction was the main source of soil available Mn and Zn. The Fe availability related mainly to the Mn oxides, Fe oxides, and exchangeable fractions. The plants absorbed Cu mainly from the Mn-oxides and organic matter fractions. Manganese absorbed by plants originated from the exchangeable and Mn-oxides fractions. The Zn absorbed by plants originated mainly from the exchangeable fraction. Correlations of single metal extractions (Mehlich-1 and DTPA) with Cu, Mn and Zn contents in plants were positive.

Knowing the accumulation of nutrients in mango plants is essential for calibrating fertilization programs aiming to increase yield in nutritionally unbalanced orchards. The work aimed to evaluate mango nutritional efficiency through nutrient accumulation and partitioning in plants of Palmer cultivar grown in sand soils at São Francisco Valley, Northwest Brazil. Commercial orchards located in Bahia and Pernambuco States, Brazil, under semi-arid climate (BShw; 400-800 mm annual rainfall) had the vegetable biomass and nutrient contents in the mango compartments determined in 1, 2, 4, 7, and 12 years old plants, by evaluating four plants of each age from 20 sample units. The separated samples of the harvested trees originated the compartments roots, stems, thick twigs, thin twigs, leaves and fruits. Nutrient contents and plant dry matter per compartment were determined and plant nutrient accumulation evaluated. Biomass and fruits coefficient of biological utilization were calculated. There was increment in the accumulated content of macronutrients in the mango plants over the years, with superiority for N and K, for which there was a sharp increase as compared to the other macronutrients. Manganese and Fe were the most accumulated micronutrients in the plants over the years. The canopy of the mango Palmer plants is the compartment that accumulates more macro and micronutrients, and the partition within the canopy occurs in the sequence: leaf> thin twig> thick twig. Phosphorus and Mg, and Cu and B are the nutrients more efficient to generate plant biomass and fruit production in the mango Palmer orchards.