Molecular prevalence of Mycoplasma parvum in production cycle of technified swine herds / Prevalência molecular do Mycoplasma parvum em granjas de suínos tecnificados de ciclo completo

Porcine hemoplasmosis is characterized as a geographically cosmopolitan disease caused by Mycoplasma suis and Mycoplasma parvum. Asymptomatic pigs are considered the focus of hemoplasmosis because they are carriers and reservoirs to new infections. This study aimed to determine the molecular occurrence of porcine hemoplasmas (PH) in the production cycle of technified farrow-to-finished swine herds. For this purpose, 20 swine herds were evaluated, where 501 whole blood samples were collected for qPCR and phylogenetic analyses for hemoplasmas. The epidemiological analysis was performed for the entire population and per the growth stage. The total prevalence for PH was 31.93% (161/501); 95% (19/20) of sampled herds were positive. The occurrence of PH by swine growth stages was nursery (30.47%), growing (31.29%), finishing (26.18%), and slaughter (40.25%). The quantification cycles (Cq) ranged from 3.18-39.56 and the number of PH 16S rRNA copies per µL of DNA ranged from 5,57 x10 to 2.23 x1010 . Sequencing and phylogenetic analysis of five selected samples showed 100% identity with M. parvum strain Indiana and two M. parvum sequences from Brazil/Goiás. This is the first report on PH in technified herds in Southeastern Brazil by growth stages.

A hemoplasmose suína é uma doença geograficamente cosmopolita, causada por Mycoplasma suis e Mycoplasma parvum. Suínos assintomáticos são considerados foco de hemoplasmose por serem portadores e reservatórios de novas infecções. Este estudo teve como objetivo determinar a ocorrência molecular de hemoplasmas suínos (HP) no ciclo de produção de rebanhos suínos tecnificados. Foram avaliados 20 rebanhos suínos e coletadas 501 amostras de sangue total para qPCR e análises filogenéticas para hemoplasmas. A análise epidemiológica foi realizada pela população e por estágio de crescimento. A prevalência total de HP foi de 31,93% (161/501); 95% (19/20) dos rebanhos amostrados foram positivos. A ocorrência de HP por fases de crescimento dos suínos foi: creche (30,47%), em crescimento (31,29%), acabamento (26,18%) e abate (40,25%). Os ciclos de quantificação (Cq) variaram de 3,18-39,56 e o número de cópias de rRNA PH 16S por µL de DNA variou de 5,57 x102 a 2,23 x10¹0. O sequenciamento e a análise filogenética de cinco amostras selecionadas mostraram 100% de identidade com a cepa indiana de M. parvum e duas sequências de M. parvum do Brasil / Goiás. Este é o primeiro relato de HP em rebanhos tecnificados, na região Sudeste do Brasil, por estágios de crescimento.

The effects on the root and plant development of soybean of organic fertilizer applications

Organic fertilizers increase soil aeration, water and nutrient holding capacity, improve seed germination and encourage the production of thicker roots, increase the yield and quality of the crop. This study was aimed to determine the effects of organic fertilizer (vermicompost, sheep manure, cattle manure, poultry manure and inorganic fertilizer as control) applications on the root and plant development of soybean during two growth stages, namely third trifoliate stage (V3) and beginning of flowering of the plants (R1) in the pot condition. The experiment was established with a two-factorial randomized plot design with four replications. The fertilizer applications had a significant effect (p<0.01) on the V3 and R1 growth stages of soybean. The highest plant height (36.78 cm) and root length (41.18 cm) were achieved with vermicompost, and the lowest plant height (21.73 cm) was recorded with inorganic fertilizer. The number of nodules was highest for vermicompost and cattle manure applications (17.16 plant-1 and 16.76 plant-1, respectively), and lowest for poultry manure (0.22 plant-1). In the R1 growth stage, poultry manure produced the highest biological fresh and dry weights, root dry weight at 25.08 g plant-1 and 5.67 g plant-1, 3.99 g plant-1 respectively. As a result, it was demonstrated that vermicompost and poultry manure applications promote strong root and plant development due to high organic matter and phosphorus and can be used successfully without inorganic fertilize application in soybean farming.

Effect of Pb-Polluted Soil on Soybean Growth and Associated Toxicological Risk.

Glycine max (L.) Merr. (soybean) has been mentioned as a potential accumulator of hazardous metals, such as Pb. The main route of human exposure to heavy metals is consumption. This study evaluates Pb accumulation in soybean at different growth stages. The aim was to determine the period of the crop development when absorption and distribution mostly occur. Soybean plants were grown in control and Pb-polluted soils in a greenhouse experiment. Morpho-physiological parameters and Pb content in organs were analyzed. Results showed that Pb affected the biomass of roots and plant height, with the highest Pb accumulation occurring in the roots and with low translocation to aerial organs. Moreover, Pb accumulation and distribution occurred before grain filling, the crop critical period. Soybean seeds accumulated Pb above permissible values, but with no associated toxicological risk. Furthermore, pods showed higher Pb values ​​than seeds, suggesting a protective effect.

Distribution, accumulation and speciation of selenium at the different growth stages of four garlic clones.

Selenium (Se) is an essential micronutrient for humans. Garlic (Allium sativum L.) metabolises Se into important Se-amino acids like Se-methylselenocysteine (Se-MetSeCys), precursor of methylselenol, an active species for cancer prevention. Therefore, the Se accumulation and speciation in garlic were studied to evaluate their relations with growth stages and types of plant clones. Four garlic clones (Nieve INTA, Union FCA, Gostoso INTA and Rubí INTA) were fortified with a Se solution (169 g Se L-1). The association of Se to different molecular weight fractions was evaluated by size-exclusion chromatography coupled to inductively coupled plasma mass spectrometry (SEC-ICP-MS) detection. Also, anion exchange chromatography (AEC-ICP-MS) was used for the determination of Se-amino acids, while their identification was performed by ESI-MS/MS. The Se was incorporated into high (7-5 kDa) and low (2-4 kDa) molecular weight fractions. The presence of Se-MetSeCys was observed mostly. Se-MetSeCys increased in bulbs to a maximum value but increased, then decreased, in leaves and roots. The Se-organic species were mostly found in bulbs in the last growth stage. Garlic showed a significant ability to accumulate and metabolise Se, specially, the red clones (Gostoso INTA and Rubí INTA). Also, this work suggests that this plant may become an attractive source of Se-amino acids with important biological properties.

Evaluation of Nanomechanical Properties of Tomato Root by Atomic Force Microscopy.

Here, different tissue surfaces of tomato root were characterized employing atomic force microscopy on day 7 and day 21 of growth through Young's modulus and plasticity index. These parameters provide quantitative information regarding the mechanical behavior of the tomato root under fresh conditions in different locations of the cross-section of root [cell surface of the epidermis, parenchyma (Pa), and vascular bundles (Vb)]. The results show that the mechanical parameters depend on the indented region, tissue type, and growth time. Thereby, the stiffness increases in the cell surface of epidermal tissue with increasing growth time (from 9.19 ± 0.68 to 13.90 ± 1.68 MPa) and the cell surface of Pa tissue displays the opposite behavior (from 1.74 ± 0.49 to 0.48 ± 0.55); the stiffness of cell surfaces of Vb tissue changes from 10.60 ± 0.58 to 6.37 ± 0.53 MPa, all cases showed a statistical difference (p < 0.05). Viscoelastic behavior dominates the mechanical forces in the tomato root. The current study is a contribution to a better understanding of the cell mechanics behavior of different tomato root tissues during growth.

Olive Leaf Extracts Toxicity to the Migratory Locust, Locusta migratoria: Histopathological Effects on the Alimentary Canal and Acetylcholinesterase and Glutathione S-Transferases Activity.

The migratory locust, Locusta migratoria (Linnaeus), is the most widespread locust species. Frequent applications of insecticides have inevitably resulted in environmental pollution and development of resistance in some natural populations of the locust. To find a new and safe alternative to conventional insecticides, experiments were conducted to assess the effect of olive leaf extracts on L. migratoria fifth instar larvae. The methanolic extracts were prepared from the leaves sampled during four phenological growth stages of olive tree which are as follows: Cluster formation (Cf), Swelling inflorescence buds (Sib), Full flowering (Ff), and Endocarp hardening (Eh). The most relevant result was noted with the extract prepared from the leaves collected at the Sib-stage. Results showed that treatment of newly emerged larvae resulted in a significant mortality with a dose-response relationship. The olive leaf extracts toxicity was also demonstrated by histopathological changes in the alimentary canal resulting in a considerable disorganization and serious damage of the midgut, ceca, and proventriculus structure. Epithelial cells alterations, less dense and degraded striated border, disintegrated regeneration crypts, vacuolarized cells, extrusion of cytoplasmic contents, and rupture of muscular layer were evident in the midgut and ceca of treated larvae. Data of biochemical analyzes showed that olive leaf extracts induced a significant decrease of the hemolymph metabolites (proteins, carbohydrates, and lipids). In a second series of experiments, we showed that the olive leaf extracts reduced the activity of acetylcholinesterase and induced the glutathione S-transferases with a dose-response relationship.

Evaluation of the Antioxidant Activity of Aqueous and Methanol Extracts of Pleurotus ostreatus in Different Growth Stages.

Total polyphenols and flavonoids contents, as well as ferric reducing antioxidant power (FRAP), metal ions chelating activity, reducing power assay and scavenging activity of DPPH and ABTS radicals in aqueous and methanolic extracts obtained from mycelium, primordium, and fruiting body of Pleurotus ostreatus in both fresh as dry, were evaluated. The total polyphenol content of dried samples was higher in aqueous extracts obtained both in room temperature and boiling. The total polyphenol content of the fresh samples obtained at room temperature and boiling was higher in aqueous extract of mycelium and in the methanolic extract of the fruiting body. In general, flavonoids represented a very small percentage of the total polyphenol content. The antioxidant activity measured by the FRAP method of extracts from fresh samples were higher with respect to the dried samples. The results of the metal ion chelating activity indicate that all extracts tested had acted. The reducing power of all samples was concentration dependent. In general, the extracts of dried samples showed higher reducing power than the extracts of fresh samples and tend to show greater reducing power by aqueous than methanolic extracts. It was observed that the DPPH and ABTS radical scavenging activities were positively correlated to the concentration of the extract. The results suggested that antioxidant activity could be due to polyphenols, but mainly by different molecules or substances present in the extracts. Overall, the fruiting body of P. ostreatus showed the best results and the possibility of continuing to investigate its functional properties of this fungus is opened. This is the first report where the antioxidant activity of P. ostreatus in different growth stage was reported.

Characterization of Injury Caused by Edessa meditabunda (F.), Chinavia impicticornis (Stål), and Piezodorus guildinii (West.) (Hemiptera: Pentatomidae) to Soybean.

Field cage trials were carried out in Ponta Grossa, Paraná, season 2010/2011, aiming to characterize and evaluate the injury caused by Edessa meditabunda (F.), Chinavia impicticornis (Stål), and Piezodorus guildinii (West.) (Hemiptera: Pentatomidae) to soybean. Non-infested plants were compared with infested plants with 2 and 3 adults/m (number of adult specimens per linear meter) at the R5.1-R9, R5.3-R9, R6-R9, and R7-R9 soybean growing stages. The following variables were analyzed: foliar retention, seed germination, and injury levels estimated by the tetrazolium test. Foliar retention index ranged from 2.3 to 4.1 in plants infested with P. guildinii and from 2.6 to 3.3 in plants infested with E. meditabunda and C. impicticornis, respectively. The lowest seed germination ranged from 66.5 to 76.5% and was observed in seeds from plants infested with 2 adults of C. impicticornis at R5.3-R9 and 3 adults of P. guildinii (R5.1-R9) and E. meditabunda (R7-R9). The highest average percentage of injury level for seeds occurred with seeds from plants infested at R5.1 with 2 or 3 adults/m of P. guildinii, ranging from 22.6 to 25.0% and from 63.6 to 68.0% in the first and second trials, respectively. Edessa meditabunda caused the highest damage to the seeds of plants infested at R7 (34.0 and 41.4%), and 2 adults/m of C. impicticornis caused the highest number of damaged seeds (54.0%) in plants infested at R6. Although both species were less harmful than P. guildinii, they could be a constraint factor for grain and seed commercialization.

Incremento da sobrevivência de colmos em cevada através da adubação nitrogenada no período de alongamento dos colmos / Shoots survival increment in barley by nitrogen supply in the shoots elongation stage

O trabalho teve como objetivos avaliar o acúmulo de matéria seca (MS) e de nitrogênio (N) da parte aérea de plantas de cevada e a taxa de sobrevivência de colmos em função da época de aplicação de N. Um experimento foi realizado em Eldorado do Sul, RS, em 2000, testando seis épocas de aplicação de N (emergência das plântulas, emissão da 3ª folha, 5ª folha, 7ª folha, 9ª folha do colmo principal (CP) e no emborrachamento) e duas doses de N (40 e 80kg ha-1). Foram determinados os acúmulos de MS e N da parte aérea no período entre o início do alongamento dos colmos e o florescimento e a taxa de sobrevivência de colmos. As aplicações de N entre a emergência das plântulas e a emissão da 9ª folha do CP resultaram nas maiores taxas de acúmulo de MS. Entretanto, as maiores taxas de acúmulo de N foram observadas com a aplicação de N no período de alongamento dos colmos. As maiores porcentagens de sobrevivência de colmos também foram observadas com a aplicação de N nesse período, mostrando a relação existente entre a necessidade de N para dar aporte ao alongamento dos colmos e a mortalidade de afilhos.

This study was aimed at evaluating the dry matter (DM) and nitrogen (N) accumulation in aerial part of barley plants and the shoot survival rate in function of time of N supply. An experiment was carried out in Eldorado do Sul, RS, in 2000, where six times of N supply (seedling emergence; 3rd leaf; 5th leaf; 7th leaf; 9th leaf emergence and boot stage) and two N rates (40 and 80kg ha-1) were tested. The DM and N accumulation among the shoot elongation begin and the bloom stage and the shoot survival rate were determined. The N supply among seedling emergence and 9th leaf emergence stage resulted the largest DM rates accumulations. However, the largest N rates accumulations were observed in shoot elongation period. The largest shoot survival rates were also observed in this period, showing the relation among the N necessity to support the shoot elongation process and the shoot mortality.

Adubação nitrogenada em estádios fenológicos em cevada, cultivar "MN 698"

The yield component contribution in the grain yield in barley is affected to growth stage for nitrogen supplementation. The objective of present study was to determine the critical growth stages for nitrogen fertilization in barley, cultivar MN 698. Four field experiments were carried out in Eldorado do Sul, Encruzilhada do Sul and Victor Graeff (RS), Brazil, in 2000 and 2001. Two N rates (30/40kg ha-1 and 60/80kg ha-1) were applied in six growth stages of main shoot (MS): (a) plant emergence, (b) 2nd/3rd leaf emergence, (c) 4th/5th leaf emergence, (d) 6th/7th leaf emergence, (e) 8th/9th leaf emergence and, (f) boot stage. Grain yield and yield components were analyzed. For low soil organic matter the better grain yield were observed when the N was applied at 3rd to 9th leaf emergence. The 3rd and 7th leaf emergence stages, correspondent to begging and final tiller emergence, were critical to nitrogen fertilization in barley plants. For medium soil organic matter, the time of supplementation of N not affected sensibly the grain yield.

A contribuição de cada componente do rendimento para a formação do rendimento de grãos em cevada é afetada pela época da suplementação nitrogenada na cultura. O objetivo do presente trabalho foi determinar os estádios fenológicos mais críticos para a suplementação nitrogenada em cevada, cultivar "MN 698". Foram conduzidos quatro experimentos a campo em três locais do Rio Grande do Sul (Eldorado do Sul, Encruzilhada do Sul e Victor Graeff), entre os anos agrícolas de 2000 e 2001. Testaram-se duas doses de N (30/40kg ha-1 e 60/80kg ha-1) aplicadas em seis estádios de desenvolvimento do colmo principal (CP): (a) emergência das plântulas, (b) emissão da 2ª/3ª folha, (c) emissão da 4ª/5ª folha, (d) emissão da 6ª/7ª folha, (e) emissão da 8ª/9ª folha e (f) emborrachamento. Foram avaliados o rendimento de grãos e os componentes do rendimento. Os resultados indicaram que, em condições de baixa matéria orgânica no solo, as maiores respostas em rendimentos de grãos são observadas entre a emissão da 3ª folha e a emissão da 9ª folha do CP. Dentro deste período, os estádios de emissão da 3ª e 7ª folhas do CP, correspondendo ao início e final do afilhamento, são os mais críticos para a suplementação nitrogenada na cultura. Em condições de médio teor de matéria orgânica do solo, a época de aplicação de N não afetou sensivelmente o rendimento de grãos.

Incremento da sobrevivência de colmos em cevada através da adubação nitrogenada no período de alongamento dos colmos

This study was aimed at evaluating the dry matter (DM) and nitrogen (N) accumulation in aerial part of barley plants and the shoot survival rate in function of time of N supply. An experiment was carried out in Eldorado do Sul, RS, in 2000, where six times of N supply (seedling emergence; 3rd leaf; 5th leaf; 7th leaf; 9th leaf emergence and boot stage) and two N rates (40 and 80kg ha-1) were tested. The DM and N accumulation among the shoot elongation begin and the bloom stage and the shoot survival rate were determined. The N supply among seedling emergence and 9th leaf emergence stage resulted the largest DM rates accumulations. However, the largest N rates accumulations were observed in shoot elongation period. The largest shoot survival rates were also observed in this period, showing the relation among the N necessity to support the shoot elongation process and the shoot mortality.

O trabalho teve como objetivos avaliar o acúmulo de matéria seca (MS) e de nitrogênio (N) da parte aérea de plantas de cevada e a taxa de sobrevivência de colmos em função da época de aplicação de N. Um experimento foi realizado em Eldorado do Sul, RS, em 2000, testando seis épocas de aplicação de N (emergência das plântulas, emissão da 3ª folha, 5ª folha, 7ª folha, 9ª folha do colmo principal (CP) e no emborrachamento) e duas doses de N (40 e 80kg ha-1). Foram determinados os acúmulos de MS e N da parte aérea no período entre o início do alongamento dos colmos e o florescimento e a taxa de sobrevivência de colmos. As aplicações de N entre a emergência das plântulas e a emissão da 9ª folha do CP resultaram nas maiores taxas de acúmulo de MS. Entretanto, as maiores taxas de acúmulo de N foram observadas com a aplicação de N no período de alongamento dos colmos. As maiores porcentagens de sobrevivência de colmos também foram observadas com a aplicação de N nesse período, mostrando a relação existente entre a necessidade de N para dar aporte ao alongamento dos colmos e a mortalidade de afilhos.

Incremento da sobrevivência de colmos em cevada através da adubação nitrogenada no período de alongamento dos colmos

This study was aimed at evaluating the dry matter (DM) and nitrogen (N) accumulation in aerial part of barley plants and the shoot survival rate in function of time of N supply. An experiment was carried out in Eldorado do Sul, RS, in 2000, where six times of N supply (seedling emergence; 3rd leaf; 5th leaf; 7th leaf; 9th leaf emergence and boot stage) and two N rates (40 and 80kg ha-1) were tested. The DM and N accumulation among the shoot elongation begin and the bloom stage and the shoot survival rate were determined. The N supply among seedling emergence and 9th leaf emergence stage resulted the largest DM rates accumulations. However, the largest N rates accumulations were observed in shoot elongation period. The largest shoot survival rates were also observed in this period, showing the relation among the N necessity to support the shoot elongation process and the shoot mortality.

O trabalho teve como objetivos avaliar o acúmulo de matéria seca (MS) e de nitrogênio (N) da parte aérea de plantas de cevada e a taxa de sobrevivência de colmos em função da época de aplicação de N. Um experimento foi realizado em Eldorado do Sul, RS, em 2000, testando seis épocas de aplicação de N (emergência das plântulas, emissão da 3ª folha, 5ª folha, 7ª folha, 9ª folha do colmo principal (CP) e no emborrachamento) e duas doses de N (40 e 80kg ha-1). Foram determinados os acúmulos de MS e N da parte aérea no período entre o início do alongamento dos colmos e o florescimento e a taxa de sobrevivência de colmos. As aplicações de N entre a emergência das plântulas e a emissão da 9ª folha do CP resultaram nas maiores taxas de acúmulo de MS. Entretanto, as maiores taxas de acúmulo de N foram observadas com a aplicação de N no período de alongamento dos colmos. As maiores porcentagens de sobrevivência de colmos também foram observadas com a aplicação de N nesse período, mostrando a relação existente entre a necessidade de N para dar aporte ao alongamento dos colmos e a mortalidade de afilhos.

Adubação nitrogenada em estádios fenológicos em cevada, cultivar "MN 698"

The yield component contribution in the grain yield in barley is affected to growth stage for nitrogen supplementation. The objective of present study was to determine the critical growth stages for nitrogen fertilization in barley, cultivar MN 698. Four field experiments were carried out in Eldorado do Sul, Encruzilhada do Sul and Victor Graeff (RS), Brazil, in 2000 and 2001. Two N rates (30/40kg ha-1 and 60/80kg ha-1) were applied in six growth stages of main shoot (MS): (a) plant emergence, (b) 2nd/3rd leaf emergence, (c) 4th/5th leaf emergence, (d) 6th/7th leaf emergence, (e) 8th/9th leaf emergence and, (f) boot stage. Grain yield and yield components were analyzed. For low soil organic matter the better grain yield were observed when the N was applied at 3rd to 9th leaf emergence. The 3rd and 7th leaf emergence stages, correspondent to begging and final tiller emergence, were critical to nitrogen fertilization in barley plants. For medium soil organic matter, the time of supplementation of N not affected sensibly the grain yield.

A contribuição de cada componente do rendimento para a formação do rendimento de grãos em cevada é afetada pela época da suplementação nitrogenada na cultura. O objetivo do presente trabalho foi determinar os estádios fenológicos mais críticos para a suplementação nitrogenada em cevada, cultivar "MN 698". Foram conduzidos quatro experimentos a campo em três locais do Rio Grande do Sul (Eldorado do Sul, Encruzilhada do Sul e Victor Graeff), entre os anos agrícolas de 2000 e 2001. Testaram-se duas doses de N (30/40kg ha-1 e 60/80kg ha-1) aplicadas em seis estádios de desenvolvimento do colmo principal (CP): (a) emergência das plântulas, (b) emissão da 2ª/3ª folha, (c) emissão da 4ª/5ª folha, (d) emissão da 6ª/7ª folha, (e) emissão da 8ª/9ª folha e (f) emborrachamento. Foram avaliados o rendimento de grãos e os componentes do rendimento. Os resultados indicaram que, em condições de baixa matéria orgânica no solo, as maiores respostas em rendimentos de grãos são observadas entre a emissão da 3ª folha e a emissão da 9ª folha do CP. Dentro deste período, os estádios de emissão da 3ª e 7ª folhas do CP, correspondendo ao início e final do afilhamento, são os mais críticos para a suplementação nitrogenada na cultura. Em condições de médio teor de matéria orgânica do solo, a época de aplicação de N não afetou sensivelmente o rendimento de grãos.

Tolerância da soja ao desfolhamento afetada pela redução do espaçamento entre fileiras

The row spacing reduction from 40 to 20 cm increase radiation interception, leaf area index and grain yield. This experiment aimed to evaluate if the row spacing reduction influence soybean tolerance to loss of photosynthetic area. The research was performed using no-till tillage system at the Agronomic Experimental Station of Universidade Federal do Rio Grande do Sul, during the 2000/01 growing season. Treatments were arranged in a split-split plot randomized complete block design, with four replications. Treatments included five combination of defoliation in three stages of development (V9 - ninth-node, R2 - full bloom and R5 - beginning of seed filling), two row spacings (20 and 40cm) and four defoliation levels (0 - control, 33, 67 and 100%). The cultivar tested was FT-Abyara. Defoliations performed at the reproductive stages decrease grain yield, especially when curried at the begging of grain filling (R5). The control grain yield was 21% higher when soybean was sown with rows 20cm apart (4134kg ha-1) than with 40cm rows (3413kg ha-1). Narrow rows always provided higher yields in all defoliation levels. The component that influenced yield the most was the number of pods m-2. These results indicate that row spacing reduction from 40cm to 20cm is a positive management strategy for soybean production regardless of defoliation level.

A redução do espaçamento entre fileiras de 40 para 20cm incrementa a interceptação da radiação, o índice de área foliar e o rendimento de grãos. Este trabalho objetivou avaliar se a redução do espaçamento entre fileiras influencia a tolerância da soja à perda de área fotossintética. O experimento foi conduzido, em semeadura direta na Estação Experimental Agronômica da UFRGS, na safra 2000/01. Utilizou-se o delineamento experimental de blocos ao acaso, com quatro repetições, em parcelas sub-subdivididas. Os tratamentos foram desfolhamento em três estádios de desenvolvimento (V9 - nono nó, R2 - floração e R5 - inicio enchimento de grãos), dois espaçamentos entre fileiras (20 e 40cm) e quatro níveis de desfolhamento (0 - testemunha, 33, 67 e 100%). Foi utilizada a cultivar FT-Abyara. Os desfolhamentos realizados no período reprodutivo reduziram o rendimento, sendo o estádio R5 o mais crítico. O rendimento médio de grãos da testemunha não desfolhada foi 21% maior no espaçamento de 20cm (4134kg ha-1) do que no de 40cm (3413kg ha-1) e manteve-se sempre superior, em todos os níveis de desfolhamento. O componente que mais influenciou o rendimento foi o número de legumes m-2. Estes resultados indicam que a redução do espaçamento entre fileiras de 40cm para 20cm é uma prática cultural favorável tanto para as plantas com área foliar intacta quando desfolhadas.

Tolerância da soja ao desfolhamento afetada pela redução do espaçamento entre fileiras

The row spacing reduction from 40 to 20 cm increase radiation interception, leaf area index and grain yield. This experiment aimed to evaluate if the row spacing reduction influence soybean tolerance to loss of photosynthetic area. The research was performed using no-till tillage system at the Agronomic Experimental Station of Universidade Federal do Rio Grande do Sul, during the 2000/01 growing season. Treatments were arranged in a split-split plot randomized complete block design, with four replications. Treatments included five combination of defoliation in three stages of development (V9 - ninth-node, R2 - full bloom and R5 - beginning of seed filling), two row spacings (20 and 40cm) and four defoliation levels (0 - control, 33, 67 and 100%). The cultivar tested was FT-Abyara. Defoliations performed at the reproductive stages decrease grain yield, especially when curried at the begging of grain filling (R5). The control grain yield was 21% higher when soybean was sown with rows 20cm apart (4134kg ha-1) than with 40cm rows (3413kg ha-1). Narrow rows always provided higher yields in all defoliation levels. The component that influenced yield the most was the number of pods m-2. These results indicate that row spacing reduction from 40cm to 20cm is a positive management strategy for soybean production regardless of defoliation level.

A redução do espaçamento entre fileiras de 40 para 20cm incrementa a interceptação da radiação, o índice de área foliar e o rendimento de grãos. Este trabalho objetivou avaliar se a redução do espaçamento entre fileiras influencia a tolerância da soja à perda de área fotossintética. O experimento foi conduzido, em semeadura direta na Estação Experimental Agronômica da UFRGS, na safra 2000/01. Utilizou-se o delineamento experimental de blocos ao acaso, com quatro repetições, em parcelas sub-subdivididas. Os tratamentos foram desfolhamento em três estádios de desenvolvimento (V9 - nono nó, R2 - floração e R5 - inicio enchimento de grãos), dois espaçamentos entre fileiras (20 e 40cm) e quatro níveis de desfolhamento (0 - testemunha, 33, 67 e 100%). Foi utilizada a cultivar FT-Abyara. Os desfolhamentos realizados no período reprodutivo reduziram o rendimento, sendo o estádio R5 o mais crítico. O rendimento médio de grãos da testemunha não desfolhada foi 21% maior no espaçamento de 20cm (4134kg ha-1) do que no de 40cm (3413kg ha-1) e manteve-se sempre superior, em todos os níveis de desfolhamento. O componente que mais influenciou o rendimento foi o número de legumes m-2. Estes resultados indicam que a redução do espaçamento entre fileiras de 40cm para 20cm é uma prática cultural favorável tanto para as plantas com área foliar intacta quando desfolhadas.

Estádios de desenvolvimento da cana-de-açúcar e suas relações com a produtividade

The main purpose of sugarcane plant is sucrose production that depends of environmental conditions during the growth. There is four growth stages that are affected by divers factors. Bud germination is affected by apical domination, nutrition of stalks pieces for vegetative propagation, bud position on the culm, bud position on the furrow, treatments to prevent diseases, varieties and climatic factors. After bud germination starts tillering period that depends mainly from climatic factors, fertilization, varieties and cultural practices. From tillering to sugar accumulation beginning depends basically from plant physiological age, climatic factors and fertilization. When the sugarcane cycle is completed, paralyse the growth and starts sugar concentration until reach values accepted by industries. In temperatures bigger than 18°C, the sugarcane will continue the growth until other factor determine growth paralysation and posterior sugar accumulation.

A finalidade principal da cana-de-açúcar é a produção de sacarose, que depende das condições ambientais durante o crescimento e do período de concentração de açúcar. Apresenta quatro estádios de desenvolvimento que são afetados por diversos fatores. A brotação das gemas é afetada pela dominância apical, estado nutricional do tolete, posição da gema no colmo, posição da gema no sulco, tratamento para prevenir doenças, cultivares e fatores climáticos. Logo após a brotação das gemas inicia o perfilhamento que depende principalmente dos fatores climáticos, adubação, cultivares e práticas culturais. Do final do perfilhamento ao início da acumulação de açúcar depende basicamente da idade fisiológica da planta, dos fatores climáticos e nutricionais. Ao completar o ciclo paralisa o crescimento e inicia a concentração de açúcar até atingir valores aceitáveis pela industria. Em temperaturas maiores que 18°C, a cana poderá continuar no estádio de crescimento até que outro fator determina a paralisação do crescimento e subseqüente acúmulo de açúcar. Deficiência hídrica também paralisa o crescimento e favorece a concentração de açúcar.

ESTÁDIOS DE DESENVOLVIMENTO DA CANA-DE-AÇÚCAR E SUAS RELAÇÕES COM A PRODUTIVIDADE

The main purpose of sugarcane plant is sucrose production that depends of environmental conditions during the growth. There is four growth stages that are affected by divers factors. Bud germination is affected by apical domination, nutrition of stalks pieces for vegetative propagation, bud position on the culm, bud position on the furrow, treatments to prevent diseases, varieties and climatic factors. After bud germination starts tillering period that depends mainly from climatic factors, fertilization, varieties and cultural practices. From tillering to sugar accumulation beginning depends basically from plant physiological age, climatic factors and fertilization. When the sugarcane cycle is completed, paralyse the growth and starts sugar concentration until reach values accepted by industries. In temperatures bigger than 18°C, the sugarcane will continue the growth until other factor determine growth paralysation and posterior sugar accumulation.

A finalidade principal da cana-de-açúcar é a produção de sacarose, que depende das condições ambientais durante o crescimento e do período de concentração de açúcar. Apresenta quatro estádios de desenvolvimento que são afetados por diversos fatores. A brotação das gemas é afetada pela dominância apical, estado nutricional do tolete, posição da gema no colmo, posição da gema no sulco, tratamento para prevenir doenças, cultivares e fatores climáticos. Logo após a brotação das gemas inicia o perfilhamento que depende principalmente dos fatores climáticos, adubação, cultivares e práticas culturais. Do final do perfilhamento ao início da acumulação de açúcar depende basicamente da idade fisiológica da planta, dos fatores climáticos e nutricionais. Ao completar o ciclo paralisa o crescimento e inicia a concentração de açúcar até atingir valores aceitáveis pela industria. Em temperaturas maiores que 18°C, a cana poderá continuar no estádio de crescimento até que outro fator determina a paralisação do crescimento e subseqüente acúmulo de açúcar. Deficiência hídrica também paralisa o crescimento e favorece a concentração de açúcar.