Fertilization and cover crop effects on soil nitrogen and plant nutrition in a young guarana plantation.

O presente estudo quantificou os efeitos da fertilização mineral e da cobertura do solo com uma leguminosa (Pueraria phaseoloides (Roxb) Benth.) sobre a dinâmica de nutrientes no sistema solo-planta.

Biochemical characterization of systemic bacteria in bananas, sensitivity to antibiotics and plant phytotoxicity during shoot proliferation.

2016

Nitrate in soil solution with use of plant cocktails as green manure in diferent tillage systems in the brazilian semi-arid

Tillage systems strongly affect nutrient transformations and plant availability. The objective of this study was to assess the nitrate dynamic in soil solution in different tillage systems with use of plant cocktail as green manure in fertilized melon (Cucumis melon) in Brazilian semi-arid. The treatments were arranged in four blocks in a split-plot design and included three types of cover crops and two tillage systems, conventional tillage (CT) and no-till (NT). The data showed no strong effect of plant cocktails composition on NO3-N dynamic in the soil. Mean concentration of NO3-N ranged from 19.45 mg L-1 at 15 cm to 60.16 mg L-1 at 50 cm soil depth, indicating high leachability. No significant differences were observed between NT and CT treatments for 15 cm depth. The high soil moisture content at ~ 30 cm depth concentrated high NO3-N in all treatments, mean of 54.27 mg L-1 to NT and 54.62 mg L-1 to CT. The highest NO3-N concentration was observed at 50 cm depth in TC (60.16 mg L-1). High concentration of NO3-N in CT may be attributed to increase in decomposition of soil organic matter and crop residues incorporated into the soil.

Planting times and spacing of carrot crops in the São Francisco Valley, Pernambuco state, Brazil.

Climate variations over the year and plant density tend to strongly affect the agronomic performance of carrot crops. Thus, the objective of this work was to evaluate the performance of the cultivar Brasilia in crops under mild (winter) and high (summer) temperatures. An experiment was conducted from May 2011 to February 2012, using a randomized block design and treatments arranged in split plot, with three replications. The plots consisted of planting seasons (winter and summer) and the subplots of plant spacing (4, 6, 8 and 10 cm). The height of plants presented a linear decrease, from 53.4 to 51.0 cm, with an increase in spacing in summer planting, while in winter the greatest height (50.7 cm) was obtained with spacing of 8.0 cm between plants. The lowest commercial yields were found in summer crops and with the widest spacing between plants. The smallest spacing between plants (4 cm) had yields of 45.9 Mg ha -1in summer and of 63.1 Mg ha-1 in winter crops. The winter planting had higher fresh root weight (89.9 g root - 1 ) compared to the summer (81.4 g root - 1 ), reaching higher weight with increasing plant spacing. Higher yields are achieved with plant spacing of 4 cm during winter. The carrot can be grown throughout the year in the Submiddle of the São Francisco Valley.

Sequential exhaustive extraction of a Mollisol soil, and characterizations of humic components, including humin, by solid and solution state NMR.

A comprehensive sequential extraction procedure was applied to isolate soil organic components using aqueous solvents at different pH values, base plus urea (base-urea), and finally dimethylsulfoxide (DMSO) plus concentrated H2SO4 (DMSO-acid) for the humin-enriched clay separates. The extracts from base-urea and DMSO-acid would be regarded as 'humin' in the classical definitions. The fractions isolated from aqueous base, base-urea and DMSO-acid were characterized by solid and solution state NMR spectroscopy. The base-urea solvent system isolated ca. 10% (by mass) additional humic substances. The combined base-urea and DMSO-acid solvents isolated ca. 93% of total organic carbon from the humin-enriched fine clay fraction (<2 ?m). Characterization of the humic fractions by solid-state NMR spectroscopy showed that oxidized char materials were concentrated in humic acids isolated at pH 7, and in the base-urea extract. Lignin-derived materials were in considerable abundance in the humic acids isolated at pH 12.6. Only very small amounts of char-derived structures were contained in the fulvic acids and fulvic acids-like material isolated from the base-urea solvent. After extraction with base-urea, the 0.5 m NaOH extract from the humin-enriched clay was predominantly composed of aliphatic hydrocarbon groups, and with lesser amounts of aromatic carbon (probably including some char material), and carbohydrates and peptides. From the combination of solid and solution-state NMR spectroscopy, it is clear that the major components of humin materials, from the DMSO-acid solvent, after the exhaustive extraction sequence, were composed of microbial and plant derived components, mainly long-chain aliphatic species (including fatty acids/ester, waxes, lipids and cuticular material), carbohydrate, peptides/proteins, lignin derivatives, lipoprotein and peptidoglycan (major structural components in bacteria cell walls). Black carbon or char materials were enriched in humic acids isolated at pH 7 and humic acids-like material isolated in the base-urea medium, indicating that urea can liberate char-derived material hydrogen bonded or trapped within the humin matrix.

Prediction of G protein coupled receptors from plant genomes.

2016