RESUMO

Although the burrower bug (Cyrtomenus mirabilis) is considered a vitalsoil pest in peanut crops, Arachis hypogaea L., in South America, there is little information on its occurrence and damage characterization. This study aimed to evaluate the vertical distribution and fluctuation of the burrower bug in the soil and the damage this species causes in peanuts. Two peanut cultivars (IAC OL3 and IAC 503) were evaluated in three locations in the state of São Paulo: Pindorama, Ribeirão Preto and Votuporanga, in the 2017/18 and 2018/19 harvests. Trenches were dug 0.5 m long, 0.3 m wide and 0.3 m deep, along plant lines at four spots on each sampling date, and stratified in layers 10 cm deep. Plant samples (0.5 m) were collected and evaluated for number of pods and percentage of kernels with symptoms of insect damage. More than 85 % of the C. mirabilis population was found in depths of up to 10 cm, especially after plant fructification, and an increase in nymphs from 100 days after sowing (DAS) was seen when an increased number of maturing pods was observed. The occurrence of nymphs and adults of C. mirabilis and their damage to peanut kernels was similar in both cultivars (IAC OL3 and IAC 503), when these were harvested according to their developmental cycles.

Assuntos

RESUMO

Soil tillage and agricultural traffic generate changes in soil physical attributes and affect the growth of the roots. This study evaluates the impact of system soil tillage on compaction and sugarcane root growth. The experiment was carried out on a Rhodic Kandiudox with two soil tillages (Deep Strip Tillage and Conventional Tillage) and two positions (beds or traffic lane and no traffic lane), totaling four treatments (DST-beds + no traffic lane, DST-traffic lane, CT-no traffic lane and CT-traffic lane). Soil penetration resistance (SPR), bulk density, dry mass, and root system lengths and volumes were evaluated. DST-beds presented lower values for SPR (1.45 MPa) compared to the other treatments (2.55 MPa). This lower SPR did not reflect significant increases in root growth in relation to the DST-traffic lane, meaning that the roots were not confined to the beds. The dry root mass for CT- traffic lane was 35% less than for DST- traffic lane, and CT-no traffic lane reduced of the root dry mass in the layers 0.0-0.2 and 0.2-0.4 m by 62% and 47%, respectively, compared to the DST-beds. Therefore, CT, although widely used, does not create adequate conditions for root development in the first sugarcane cycle, even in lanes with no traffic.

Assuntos

RESUMO

This study aimed to quantify nitrous oxide (N2O) and methane (CH4) emission/sink response from sugar cane soil treated with fertilizer nitrogen (N) and vinasse applied separately or in sequence, the latter being investigated with regard to the time interval between applications for a possible effect on emissions. The study was carried out in a traditional area of unburned sugar cane in São Paulo state, Brazil. Two levels of N fertilization (0 and 100 kg N ha(-1)) with no added vinasse and combined with vinasse additions at different times (100 m(-3) ha(-1) at 3 and 15 days after N fertilization) were evaluated. Methane and N2O fluxes were monitored for 211 days. On average, the soil was a sink for CH4, which was not affected by the treatments. Emissions of N2O were induced by N fertilizer and vinasse applications. For ammonium sulfate, 0.6% of the added N was emitted as N2O, while for vinasse, this ranged from 1.0 to 2.2%. Changes in N2O fluxes were detected the day after application of vinasse on the N fertilized areas, but although the emission factor (EF) was 34% greater, the EF was not significantly different from fertilizer N alone. Nevertheless, we recommend to not apply vinasse after N fertilization to avoid boosting N2O emissions.

Assuntos

RESUMO

The maintenance of sugarcane (Saccharum spp.) straw on a soil surface increases the soil carbon (C) stocks, but at lower rates than expected. This fact is probably associated with the soil management adopted during sugarcane replanting. This study aimed to assess the impact on soil C stocks and the humification index of soil organic matter (SOM) of adopting no-tillage (NT) and conventional tillage (CT) for sugarcane replanting. A greater C content and stock was observed in the NT area, but only in the 0-5 cm soil layer (p 0.05). Greater soil C stock (0-60 cm) was found in soil under NT, when compared to CT and the baseline. While C stock of 116 Mg ha-1 was found in the baseline area, in areas under CT and NT systems the values ranged from 120 to 127 Mg ha-1. Carbon retention rates of 0.67 and 1.63 Mg C ha-1 year-1 were obtained in areas under CT and NT, respectively. Laser-Induced Fluorescence Spectroscopy showed that CT makes the soil surface (0-20 cm) more homogeneous than the NT system due to the effect of soil disturbance, and that the SOM humification index (H LIF) is larger in CT compared to NT conditions. In contrast, NT had a gradient of increasing H LIF, showing that the entry of labile organic material such as straw is also responsible for the accumulation of C in this system. The maintenance of straw on the soil surface and the adoption of NT during sugarcane planting are strategies that can increase soil C sequestration in the Brazilian sugarcane sector.

RESUMO

The maintenance of sugarcane (Saccharum spp.) straw on a soil surface increases the soil carbon (C) stocks, but at lower rates than expected. This fact is probably associated with the soil management adopted during sugarcane replanting. This study aimed to assess the impact on soil C stocks and the humification index of soil organic matter (SOM) of adopting no-tillage (NT) and conventional tillage (CT) for sugarcane replanting. A greater C content and stock was observed in the NT area, but only in the 0-5 cm soil layer (p 0.05). Greater soil C stock (0-60 cm) was found in soil under NT, when compared to CT and the baseline. While C stock of 116 Mg ha-1 was found in the baseline area, in areas under CT and NT systems the values ranged from 120 to 127 Mg ha-1. Carbon retention rates of 0.67 and 1.63 Mg C ha-1 year-1 were obtained in areas under CT and NT, respectively. Laser-Induced Fluorescence Spectroscopy showed that CT makes the soil surface (0-20 cm) more homogeneous than the NT system due to the effect of soil disturbance, and that the SOM humification index (H LIF) is larger in CT compared to NT conditions. In contrast, NT had a gradient of increasing H LIF, showing that the entry of labile organic material such as straw is also responsible for the accumulation of C in this system. The maintenance of straw on the soil surface and the adoption of NT during sugarcane planting are strategies that can increase soil C sequestration in the Brazilian sugarcane sector.

RESUMO

The region of Ribeirão Preto City, southeastern Brazil, is an important sugar cane and recharge area for grounwater of the Guarany aquifer. This research was conducted to evaluate the potential contamination of groundwater with nitrates in the area and in surrounding municipal wells. No significant amount of nitrate was found in the recharge agricultural area. However, nitrate levels were detected at concentrations higher than the Maximum Concentration Level (MCL) of 6.0 mg/L in a downtown, urban, well located away from agriculture, which had no history of nitrogen application, reaching values higher than the maximum risk coefficient for infants (RC) of 1.0.

Assuntos

RESUMO

Foram realizados 16 experimentos em campo, no ano agrícola de 2001/02, nas principais regiões produtoras de algodão do Estado de São Paulo, objetivando avaliar o comportamento de 12 genótipos de algodoeiro em relação à produtividade, à qualidade da fibra e à resistência a seis doenças da cultura. Foi utilizado o delineamento de blocos completos ao acaso, com quatro repetições, cada uma delas representada por duas linhas de 5 metros de comprimento. Diferenças substanciais foram observadas entre os genótipos com respeito à produtividade, quer de algodão em caroço, quer de fibra. Apesar de se mostrar destacada em alguns genótipos, a porcentagem de fibra não constituiu fator predominante na produção de fibra por área. Entre as 12 cultivares estudadas, somente "CNPA ITA 90" e "BRS IPÊ" apresentaram bom índice de resistência à ramularia. Por outro lado, a "IAC 24" apresentou bom índice para murcha de Fusarium, nematóides e ramulose, as três doenças mais destrutíveis. A maioria das cultivares e linhagens estudadas revelou suscetibilidade a uma ou mais das doenças estudadas, não apresentando genótipo com resistência múltipla a todas as doenças consideradas.

In the 2001/02 growing season 16 field experiments were conducted in the main cotton producing regions of the state of São Paulo to evaluate the performance of 12 cotton genotypes for yield, fiber quality and resistance to six diseases of the crop. A randomized complete block design with four replications, which were represented by two five-meter-long rows now used. Substantial differences between genotypes were observed for both cotton seed and fiber. Although outstanding in some genotypes, the fiber percentage was not a determining factor of fiber yield per area. Among the 12 genotypes studied, only 'CNPA ITA 90' and 'BRS IPÊ' presented good index of resistance to the ramularia. On the other hand, 'IAC 24' presented good index for Fusarium, nematodes and ramulose, the three more destructible diseases.Most of the evalueted cultivars and lines were susceptible to one or more diseases; none of them showed multiple resistance to all diseases.

RESUMO

Foram realizados 16 experimentos em campo, no ano agrícola de 2001/02, nas principais regiões produtoras de algodão do Estado de São Paulo, objetivando avaliar o comportamento de 12 genótipos de algodoeiro em relação à produtividade, à qualidade da fibra e à resistência a seis doenças da cultura. Foi utilizado o delineamento de blocos completos ao acaso, com quatro repetições, cada uma delas representada por duas linhas de 5 metros de comprimento. Diferenças substanciais foram observadas entre os genótipos com respeito à produtividade, quer de algodão em caroço, quer de fibra. Apesar de se mostrar destacada em alguns genótipos, a porcentagem de fibra não constituiu fator predominante na produção de fibra por área. Entre as 12 cultivares estudadas, somente "CNPA ITA 90" e "BRS IPÊ" apresentaram bom índice de resistência à ramularia. Por outro lado, a "IAC 24" apresentou bom índice para murcha de Fusarium, nematóides e ramulose, as três doenças mais destrutíveis. A maioria das cultivares e linhagens estudadas revelou suscetibilidade a uma ou mais das doenças estudadas, não apresentando genótipo com resistência múltipla a todas as doenças consideradas.(AU)

In the 2001/02 growing season 16 field experiments were conducted in the main cotton producing regions of the state of São Paulo to evaluate the performance of 12 cotton genotypes for yield, fiber quality and resistance to six diseases of the crop. A randomized complete block design with four replications, which were represented by two five-meter-long rows now used. Substantial differences between genotypes were observed for both cotton seed and fiber. Although outstanding in some genotypes, the fiber percentage was not a determining factor of fiber yield per area. Among the 12 genotypes studied, only 'CNPA ITA 90' and 'BRS IPÊ' presented good index of resistance to the ramularia. On the other hand, 'IAC 24' presented good index for Fusarium, nematodes and ramulose, the three more destructible diseases.Most of the evalueted cultivars and lines were susceptible to one or more diseases; none of them showed multiple resistance to all diseases.(AU)

Assuntos

RESUMO

This study was undertaken to evaluate the degradation and mobility of the herbicide tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N'-dimethylurea) in soil under field conditions, and its potential for leaching and groundwater contamination. A watershed, Espraiado, located over a recharge area in Brazil, was chosen for soil and water studies. At Espraiado, water samples were collected from seven wells at intervals of three months from March 2004 to June 2006 and analyzed for tebuthiuron. Other samples were taken from city wells located outside of the recharge area. To assess the potential movement to the aquifer, tebuthiuron was also applied to trial plots at the recommended label rate of 1.0 kg/ha a.i. in May of 2004, with and without sugarcane coverage, on sandy soil. Soil samples were collected during the years of 2004 and 2005, at depths intervals of 20 cm from soil surface down to 120 cm and analyzed for tebuthiuron at zero, 3, 30, 60, 90, 120, 150, 180, 240, and 300 days after application. There was no clear effect of sugarcane coverage on the tebuthiuron degradation in soils, but it moved faster into the soil where there was no cover. After 180 days there were no measurable residues in the soil, and tebuthiuron was not found below 40 cm depth in any time. Tebuthiuron had a half-life of 20 days under those conditions. No tebuthiuron residue was found in ground water samples at any sampling time.

Assuntos

RESUMO

Fifty-six Brazilian commercial maize cultivars were examined for FB1 and FB2 accumulation after two non-consecutive growing seasons. During the 94/95 growing season 35 cultivars were planted at three locations in the state of São Paulo, Brazil. All samples (total of 105) were contaminated (0.10 micro/g-6.58 microg/g FB1 and 0.04 microg/g-2.15 microg/g FB2). During the 97/98 growing season, 8 of the cultivars used during 94/95 and 21 others were replanted at the same locations. All 87 samples were contaminated (1.15 microg/g-43.80 microg/g FB1 and 0.08 microg/g-11.65 microg/g FB2). One cultivar accumulated significantly less fumonisins in all locations during both growing seasons, indicating that some degree of selection may be possible even in climates that favor F. moniliforme (verticillioides) infection of maize. The presence of water surplus in soil from kernel maturity to harvest correlated with concentrations of FB1 in the grain for the 8 cultivars planted during both seasons at three locations. Observed trends indicated that water excesses and deficits from silking to harvest increased fumonisin levels. The difference in the incidence of FB1, FB2, and FB1 + FB2 was significant between growing seasons, planting locations and between cultivars. Neither the level of hybridization, nor the type of endosperm, nor the length of the vegetative cycle showed any effect on the FB1 contamination.

Assuntos

RESUMO

Twenty three samples, belonging to 19 corn cultivars with distinct types of germoplasms, endosperm and length of vegetative cycle, were analyzed for fumonisins B1 and B2. The cultivars were grown in experimental fields in three locations (Votuporanga, Ribeirão Preto and Capão Bonito) within the State of São Paulo, Brazil, during the 97/98 crop. All samples were contaminated with fumonisins with concentrations ranging from 1.63 µg/g to 25.69 µg/g with an average of 5.61 µg/g for FB1 and from 0.38 µg/g to 8.60 µg/g with an average of 1.86 µg/g for FB2. In terms of fumonisins, these high levels put the corn cultivated in São Paulo among the most contaminated in the world reported to date.

Vinte e três amostras, representando 19 cultivares de milho com diferentes tipos de germoplasma, de endosperma e ciclo vegetativo, foram avaliadas quanto ao teor de fumonisinas em três Estações Experimentais do Instituto Agronômico (Capão Bonito, Ribeirão Preto e Votuporanga) em São Paulo, Brasil, durante a safra de 97/98. Todos os cultivares analisados estavam contaminados com fumonisinas em níveis que variaram de 1.63 µg/g a 25.69 µg/g e uma média de 5.61 µg/g FB1 e de 0.38 µg/g a 8.60 µg/g e uma média de 1.86 µg/g FB2. Estes níveis tão elevados colocam o milho cultivado no Estado de São Paulo entre os mais contaminados do mundo em termos de fumonisinas.

RESUMO

Twenty three samples, belonging to 19 corn cultivars with distinct types of germoplasms, endosperm and length of vegetative cycle, were analyzed for fumonisins B1 and B2. The cultivars were grown in experimental fields in three locations (Votuporanga, Ribeirão Preto and Capão Bonito) within the State of São Paulo, Brazil, during the 97/98 crop. All samples were contaminated with fumonisins with concentrations ranging from 1.63 µg/g to 25.69 µg/g with an average of 5.61 µg/g for FB1 and from 0.38 µg/g to 8.60 µg/g with an average of 1.86 µg/g for FB2. In terms of fumonisins, these high levels put the corn cultivated in São Paulo among the most contaminated in the world reported to date.

Vinte e três amostras, representando 19 cultivares de milho com diferentes tipos de germoplasma, de endosperma e ciclo vegetativo, foram avaliadas quanto ao teor de fumonisinas em três Estações Experimentais do Instituto Agronômico (Capão Bonito, Ribeirão Preto e Votuporanga) em São Paulo, Brasil, durante a safra de 97/98. Todos os cultivares analisados estavam contaminados com fumonisinas em níveis que variaram de 1.63 µg/g a 25.69 µg/g e uma média de 5.61 µg/g FB1 e de 0.38 µg/g a 8.60 µg/g e uma média de 1.86 µg/g FB2. Estes níveis tão elevados colocam o milho cultivado no Estado de São Paulo entre os mais contaminados do mundo em termos de fumonisinas.