NUTRIENT DEMAND BY THE CARROT CROP IS INFLUENCED BY THE CULTIVAR

Farmers must carefully choose the cultivar to be grown for a successful carrot crop. The yield potential of the cultivar may influence nutrient demand and should be known to plan for fertilization application. The aim of this study was to evaluate the cultivar effect on carrot yield and on the nutrient content and quantities allocated to leaves and roots. Three experiments were set up in two crop seasons in Rio Paranaíba, MG, Brazil. In the first season, typical summer, 10 summer cultivars were sown. In the second season, summer-winter (transition), two experiments were set up, one with summer cultivars and the other with winter cultivars. The treatments consisted of the carrot cultivars distributed in randomized blocks with four replications. Fresh and dry matter of the roots and leaves was quantified. Yield was calculated based on fresh matter of the roots. The nutrient content in leaves and roots was determined at the time of harvest. These contents and the dry matter production of roots and leaves were used to calculate nutrient uptake and export. The greatest average for total and commercial yield occurred in the crop under summer conditions. Extraction of N and K for most of the cultivars in the three experiments went beyond the amounts applied through fertilizers. Thus, there was contribution of nutrients from the soil to obtain the yields observed. However, the amount of P taken up was considerably less than that applied. This implies that soil P fertility will increase after cropping. The crop season and the cultivars influenced yield, nutrient content in the leaves and roots, and extraction and export of nutrients by the carrot crop.

Hydro-Physical Properties of a Typic Hapludult under the Effect of Rice Husk Ash

ABSTRACT The combustion of rice husk generates a partially burnt mixture called rice husk ash (RHA) that can be used as a source of nutrients to crops and as a conditioner of soil physical properties. The objective of this study was to evaluate the effect of RHA levels on the hydro-physical properties of a Typic Hapludult. The experimental design was composed of random blocks with four replications, which comprised plots of 24 m2 and treatments with increasing RHA rates: 0, 40, 80 and 120 Mg ha-1. Undisturbed soil samples were collected in the soil layers of 0.00-0.10 and 0.10-0.20 m after nine months of RHA application, using steel cylinders (0.03 m of height and 0.047 m of diameter). These samples were used to determine soil bulk density (Bd), total soil porosity (TP), soil macroporosity (Ma), soil microporosity (Mi) and the available water capacity (AWC). Disturbed soil samples were collected to determine the stability of soil aggregates in water, mean weight diameter of water stable aggregates (MWD), and soil particle size distribution. The results show that, as the RHA rate increased in the soil, Bd values decreased and TP, Ma and MWD values increased. No effect of RHA was found on Mi and AWC values. The effects of RHA on the S parameter (Dexter, 2004), precompression stress and compression index (Dias Junior and Pierce, 1995) values are consistent those shown for density and total porosity. Rice husk ash was shown to be an efficient residue to improve soil physical properties, mainly at rates between 40 and 80 Mg ha-1. Rice husk ash reduces bulk density and increases total porosity, macroporosity and soil aggregation, but does not affect microporosity, field capacity, permanent wilting point, and available water capacity of the soil. The effect of rice husk ash on the S parameter, precompression stress and index compressibility coefficient values are consistent with those observed for the bulk density and total porosity.

Estudo comparativo entre sistemáticas de digitalização de documentos: formatos HTML e PDF

Este artigo apresenta o resultado de experimentos realizados pelo Laboratório de Biblioteca Digital da PUCRS voltados para a captura e conversão de documentos a partir do formato tradicional (papel) para o formato digital. São apresentadas e avaliadas as principais etapas envolvidas no processo de digitalização utilizando duas sistemáticas diferentes: uma baseada na conversão para HTML; a outra baseada na geração de arquivos PDF usados pelo software Adobe Acrobat Reader. São abordados também fatores essenciais aos trabalhos de digitalização tais como tecnologias de Reconhecimento Óptico dos Caracteres (OCR) e avaliação das características do acervo a ser digitalizado. Por fim, é realizado um comparativo entre as duas sistemática estudadas, apontando pontos positivos e negativos que devem ser considerados na escolha de uma diretriz de trabalho.

Effect of soil interacting herbicides on soybean nodulation in Balcarce, Argentina

Two trials were performed in Balcarce, Argentina (37° 45' LS; 58° 18' LW) during 1993-94, to assess the effect of eight herbicides applied individually or in tank mixtures, on nodule number, nodule dry weight, seed yield and N percent in seed in soybean Asgrow 3205, inoculated with Bradyrhizobium japonicum CB 1809. Individual herbicides and doses in kg ha-1 of a.i. were metribuzin (0.48), acetochlor (0.90), metolachlor (1), flumioxazin (0.075), trifluralin (0.96), imazaquin (0.20), imazethapyr (0.10) and chlorimuron ethyl (0.0125). The mixtures were metribuzin+acetochlor (0.48+0.9), flumioxazin+acetochlor (0.075+0.9), imazaquin+acetochlor (0.2+0.9), metribuzin+metolachlor (0.48+1.92), and flumioxazin+ metolachlor (0.075+1.92). A control treatment without herbicides was included. Both trials were laid out as randomized complete blocks with four replicates, on a loam illitic thermic petrocalcic Paleudoll, 5.7% organic matter (OM), 25% clay, 30.4 cmol kg-1 CEC. Nodules were sampled at V2 (second node), V6 (sixth node) and R5 (beginning seed) growth stages. Herbicides did not significantly affect the beginning of nodulation or nodule number and mass at R5, not either grain yield or N accumulation. This indicates lack of interference between soil interacting herbicides and N fixation in the high organic matter, loam soils of SE Buenos Aires province, even though a tendency in less number and dry weight of nodules was evident at the two latter growth stages.

Analysis of experiments in square lattice with emphasis on variance components. i. Individual analysis

This paper focused on four alternatives of analysis of experiments in square lattice as far as the estimation of variance components and some genetic parameters are concerned: 1) intra-block analysis with adjusted treatment and blocks within unadjusted repetitions; 2) lattice analysis as complete randomized blocks; 3) intrablock analysis with unadjusted treatment and blocks within adjusted repetitions; 4) lattice analysis as complete randomized blocks, by utilizing the adjusted means of treatments, obtained from the analysis with recovery of interblock information, having as mean square of the error the mean effective variance of this same analysis with recovery of inter-block information. For the four alternatives of analysis, the estimators and estimates were obtained for the variance components and heritability coefficients. The classification of material was also studied. The present study suggests that for each experiment and depending of the objectives of the analysis, one should observe which alternative of analysis is preferable, mainly in cases where a negative estimate is obtained for the variance component due to effects of blocks within adjusted repetitions.

Agronomic performance of quinoa selected in the Brazilian Savannah

Twenty six breeding lines, selected from individual plant progenies of hybrids among varieties Amarilla de Marangani, Blanca de Junín, Chewecca, Faro 4, Improved Baer, Kancolla, Real, and Salares-Roja, had their agronomic characters evaluated, in Planaltina, DF, Brazil (15º36'S and 47º12'W), 1,000 masl, in randomized complete blocks, on a Ferralsol, previously limed and fertilized. Grain yield was positively associated with plant height, inflorescence length and diameter, and plant cycle. Genetic gain can be attained by selection based in these characters for commercial production of quinoa in tropical regions.

Designs and model effects definitions in the initial stage of a plant breeding program

The objective of this work was to compare the relative efficiency of initial selection and genetic parameter estimation, using augmented blocks design (ABD), augmented blocks twice replicated design (DABD) and group of randomised block design experiments with common treatments (ERBCT), by simulations, considering fixed effect model and mixed model with regular treatment effects as random. For the simulations, eight different conditions (scenarios) were considered. From the 600 simulations in each scenario, the mean percentage selection coincidence, the Pearsons´s correlation estimates between adjusted means for the fixed effects model, and the heritability estimates for the mixed model were evaluated. DABD and ERBCT were very similar in their comparisons and slightly superior to ABD. Considering the initial stages of selection in a plant breeding program, ABD is a good alternative for selecting superior genotypes, although none of the designs had been effective to estimate heritability in all the different scenarios evaluated.

Green manure incorporation timing for organically grown broccoli

The objective of this work was to determine the effect of incorporation timing of the velvet bean (Stizolobium cinereum) (GM) on both organic broccoli yield and N status. Mineral N content in the soil, biologically fixed N recovery by broccoli, GM biomass decomposition and N release kinetics were also determined. Plots were fertilized with 12 Mg ha-1 of organic compost and received GM either at 0, 15, 30 or 45 days after transplant. Other treatments were compost (12 or 25 Mg ha-1), GM, mineral fertilizers and control (no fertilizer). The data were collected in four completely randomized blocks. GM decomposition increased mineral N content in soil as rapidly as mineral fertilizer or the supply of 25 Mg ha-1 of compost. The N half-life in GM (24 days) is smaller than the mass half-life (35 days) and the biological fixation contributed with 23.6% of N present in the aboveground biomass of broccoli. The result suggests a higher synchrony between the crop relative growth rate and N release from the GM when incorporated at crop early growth stage. The incorporation of GM until 15 days after transplanting replaces 50% of the highest compost dose, without yield loss.

Genetic characterization and nitrogen fixation capacity of Rhizobium strains on common bean

This study aimed to genetically characterize four new Rhizobium strains, and to evaluate their nodulation and fixation capacity compared to commercial strains and to native rhizobia population of a Brazilian Rhodic Hapludox. Two experiments were carried out in randomized blocks design, under greenhouse conditions, in 2007. In the first experiment, the nodulation and nitrogen fixation capacity of new strains were evaluated, in comparison to the commercial strains CIAT-899 and PRF-81 and to native soil population. It was carried out in plastic tubes filled with vermiculite. DNA extractions and PCR sequencing of the intergenic space were made from the isolated pure colonies, in order to genetically characterize the strains and the native rhizobia population. In the second experiment, the nodulation and productivity of common beans Perola cultivar were determined, with the use of evaluated strains, alone or in mixture with PRF-81 strain. It was carried out in pots filled with soil. The native soil population was identified as Rhizobium sp. and was inefficient in nitrogen fixation. Three different Rhizobium species were found among the four new strains. The LBMP-4BR and LBMP-12BR new strains are among the ones with greatest nodulation and fixation capacity and exhibit differential responses when mixed to PRF-81.

Elephant grass genotypes for bioenergy production by direct biomass combustion

The objective of this work was to evaluate elephant grass (Pennisetum purpureum Schum.) genotypes for bioenergy production by direct biomass combustion. Five elephant grass genotypes grown in two different soil types, both of low fertility, were evaluated. The experiment was carried out at Embrapa Agrobiologia field station in Seropédica, RJ, Brazil. The design was in randomized complete blocks, with split plots and four replicates. The genotypes studied were Cameroon, Bag 02, Gramafante, Roxo and CNPGL F06-3. Evaluations were made for biomass production, total biomass nitrogen, biomass nitrogen from biological fixation, carbon/nitrogen and stem/leaf ratios, and contents of fiber, lignin, cellulose and ash. The dry matter yields ranged from 45 to 67 Mg ha-1. Genotype Roxo had the lowest yield and genotypes Bag 02 and Cameroon had the highest ones. The biomass nitrogen accumulation varied from 240 to 343 kg ha-1. The plant nitrogen from biological fixation was 51% in average. The carbon/nitrogen and stem/leaf ratios and the contents of fiber, lignin, cellulose and ash did not vary among the genotypes. The five genotypes are suitable for energy production through combustion.

Earthworm assemblages in an ecotone between forest and arable field and their relations with soil properties

The objective of this work was to assess the effects of a forest-field ecotone on earthworm assemblages. Five sites (blocks) differing in the type of crop rotation used in the field were studied in Central Bohemia, Czech Republic. In each block, sampling was carried out in seven parallel rows perpendicular to a transect from a forest (oak or oak-pine) to the centre of a field, both in spring and autumn 2001-2003. Individual rows were located in the forest (5 m from the edge), in the forest edge, and in the field (at 5, 10, 25, 50 and 100 m distances from the forest edge). The density and biomass of earthworms were lowest in the forest, increased markedly in the forest edge, decreased again at 5 or 10 m distance from the forest edge and then continuously increased along the distance to the field boundary. The highest number of species was found in the forest edge and in the field boundary. Individual species differed in their distribution along the transect. Both density and biomass of earthworms were correlated with distance from forest edge, soil organic matter content, soil porosity, and water infiltration rate.

Low-P tolerance mechanisms and differential gene expression in contrasting wheat genotypes

The objectives of this study were to determine low-P tolerance mechanisms in contrasting wheat genotypes and to evaluate the association of these mechanisms to differential gene expression. Wheat seedlings of cultivars Toropi (tolerant to low-P availability) and Anahuac (sensitive) were evaluated. Seedlings were hydroponically grown in the absence or presence of P (1.0 mmol L-1) during three different time periods: 24, 120 and 240 hours. Free phosphate (Pi) and total P contents were measured in shoots and roots. The experiment's design was in randomized blocks with three replicates, each formed by ten plants. The relative expression of genes encoding the malate transporter TaALMT1 and the transcription factor PTF1 was evaluated. Phosphorus starvation beyond ten days increased the expression of TaALMT1 only in 'Toropi'. PTF1's expression was early induced in both genotypes under P starvation, but remained significant after ten days only in 'Toropi'. Shoot Pi concentration in 'Toropi' was independent from P availability; under starvation, 'Toropi' favored the maintenance of shoot Pi concentration. The low-P tolerance of Toropi cultivar at initial growth stages is mainly due to its ability to maintain constant the Pi shoot level.

Adaptation of anthurium cultivars as cut flowers in a subtropical area

The objective of this work was to evaluate the adaptation of anthurium (Anthurium andraeanum) cultivars as cut flowers in a subtropical area, located in north of Paraná State, Brazil. The Apalai, Ianomami, Kinã, nK 102, Parakanã, Rubi, and Terena cultivars were cultivated in a nursery under 80% shade. The number of leaves and inflorescences, floral stem length, length and width of inflorescences, and spadix length were evaluated. The experimental design was in completely randomized blocks, with six replicates and five plants per plot. During the 18 months evaluated, 'Parakanã' produced 11 inflorescences per plant, whereas the other cultivars produced seven to nine inflorescences per plant. The number of leaves produced per plant was: 'Ianomami', 25; 'Parakanã', 20; 'Apalai' and 'Terena', 15; 'Kinã' and 'Rubi', 11; and 'nK 102', 9. The Apalai, nK 102, Parakanã, and Rubi cultivars are the most recommended as cut flowers; the Ianomami cultivar is not recommended as a cut flower in this region.

Ammonium and nitrate in soil and upland rice yield as affected by cover crops and their desiccation time

The objective of this work was to evaluate the effect of cover crops and their desiccation times on upland rice yield and on the levels of nitrate and ammonium in a no-tillage soil. The experiment was carried out in a randomized blocks, with split plots and three replicates. Cover crops (plots) were sowed in the off-season (March 2009). In November 2009, at 30, 20, 10 and 0 days before rice sowing (split plots), herbicide was applied on the cover crops (fallow, Panicum maximum, Urochloa ruziziensis, U. brizantha and millet). Straw and soil were sampled (0 - 10 cm) at the sowing day, and after 7, 14, 21, 28 and 35 days. Straws from millet and fallow were degraded more rapidly and provided the lowest level of nitrate in the soil. Urochloa ruziziensis, U. brizantha and P. maximum produced higher amounts of dry matter, and provided the highest levels of nitrate in the soil. Millet provides the lowest nitrate/ammonium ratio and the highest upland rice yield. Desiccations carried out at 30 and 20 days before sowing had the largest levels of nitrate in the soil at the sowing date. Nitrogen content and forms in the soil are affected by cover crops and their desiccation times.

Management of slips and its effect on growth and production of 'Pérola' pineapple plants

The lack of good quality planting material has limited the expansion and contributed to yield reduction of the Brazilian pineapple culture. Alternatives of 'Pérola' pineapple slips management were studied aiming at obtaining superior planting material within a shorter time period and making good use of healthy slips of low vigor, that are commonly discarded by growers. Two experiments were carried out at the Experimental Field of Embrapa Cassava & Fruits, Cruz das Almas, Bahia, Brazil, and another one in a commercial plantation in the region of Itaberaba, BA, using blocks or entirely randomized designs with at least four replications. In the first one, the development of slips of different initial sizes (6 to 20 cm long), when grown on mother plants after fruit harvest, was compared with that of slips grown in a nursery after their removal from the mother plants. It became clear that larger slips grow more vigorously and that the removal from the mother plant delays their growth. However, results from the second study showed that those slips grown in nursery had vegetative and agronomic performance similar to that of conventional slips and close to that of plantlets produced from plant stem sections. Independently from the type of planting material used, the larger ones presented a more vigorous growth and produced higher yields. In the third study, it was observed the influence of mineral fertilization, pest control and growth regulator application after fruit harvest on slip development. The treatments applied did not significantly accelerate slip growth. Slips reached 50 cm length and at least 300 g fresh weight within 90 days after fruit harvest, indicating that vigorous plants have enough nutritional storage material for slips development.