RESUMO

In recent years, the avocado has been one of the most dynamic fruits in the world market. In particular, cv. Hass stands out due to its productivity, nutritional quality, and acceptance. Under tropical conditions, weather elements, especially air temperature, and precipitation, affect the productivity and quality of cv. Hass. However, in tropical environments, many relationships between weather and phenological aspects of this cultivar are still unknown. Given this situation, our aim was to identify the variation and degree of association between the phenology of avocado cv. Hass and thermal time (TT) under low-latitude conditions. Eight commercial fields planted with cv. Hass grafted onto Antillean genotypes, located in an altitudinal transect between 1,700 and 2,500 m, were evaluated. The evaluation was carried out for three years and was focused on determining the differences in avocado phenological patterns associated with different environmental variables monitored by weather stations at each location. Air temperature data were used to calculate the base temperature (BT) using different methods for all phenological stages. Later the TT was determined for each stage and all locations. The results show that the duration of each phenological stage varies as a function of elevation (air temperature) and that the phenological stages overlap at the regional, crop field, and plant levels at different periods of the year, generating a high phenological variability but with specific patterns associated with temperature and precipitation. The BT for each phenological stage varied between 0.3 and 7.5 °C, and TT was found to vary depending on the method of calculation. Our work suggests that the generalization of a BT of 10 °C is not applicable for avocado cv. Hass crops under tropical conditions, specifically in the case of Colombia. Detailed studies of phenological relationships with respect to climatic variables will allow a better approximation of the productive behavior of avocado cv. Hass.

RESUMO

Cleruchoides noackae Lin & Huber (Hymenoptera: Mymaridae) was imported to Brazil in 2012, to manage the exotic pest Thaumastocoris peregrinus Carpintero & Dellapé (Hemiptera: Thaumastocoridae), which has been damaging eucalyptus plantations. Knowledge of the thermal requirements and the fertility life table of C. noackae is important to improve mass rearing methods for this parasitoid and the effectiveness of its release to manage T. peregrinus. The objective was to evaluate the development period, thermal requirements and the fertility life table of C. noackae at different temperatures. The egg-adult period of this parasitoid varied from 43 to 14 days at 15 °C and 30 °C, respectively. The emergence of C. noackae adults was higher at 15 °C, 18 °C, 21 °C and 24 °C than at 30 °C. Female and male C. noackae need 226.75 and 230.41 degree-days and temperatures higher than 10.06 °C and 9.90 °C, respectively, to complete egg-adult development. The number of parasitized eggs per C. noackae female was higher at 21 °C, 24 °C and 27 °C, with 5.82, 7.73 and 5.50 eggs, respectively, than at 30 °C (0.45). Cleruchoides noackae longevity was greater at 15 °C, 21 °C and 24 °C. The net reproductive rate of the parasitoid was higher at 21 °C and 24 °C than at 30 °C, 3.05, 4.70 and 0.16, respectively. The finite rate of increase of C. noackae was greater at 21 °C, 24 °C and 27 °C, than at 30 °C and the intrinsic rate of increase was negative at 30 °C, -0.100. The temperatures 21 °C and 24 °C and from 18 °C to 27 °C are the most adequate for the reproduction and population increase of C. noackae parasitizing eggs of T. peregrinus, respectively.

Assuntos

RESUMO

Temperate perennial fruit and nut trees play varying roles in world food diversity-providing edible oils and micronutrient, energy, and protein dense foods. In addition, perennials reuse significant amounts of biomass each year providing a unique resilience. But they also have a unique sensitivity to seasonal temperatures, requiring a period of dormancy for successful growing season production. This paper takes a global view of five temperate tree fruit crops-apples, cherries, almonds, olives, and grapes-and assesses the effects of future temperature changes on thermal suitability. It uses climate data from five earth system models for two CMIP6 climate scenarios and temperature-related indices of stress to indicate potential future areas where crops cannot be grown and highlight potential new suitable regions. The loss of currently suitable areas and new additions in new locations varies by scenario. In the southern hemisphere (SH), end-century (2081-2100) suitable areas under the SSP 5-8.5 scenario decline by more than 40% compared to a recent historical period (1991-2010). In the northern hemisphere (NH) suitability increases by 20% to almost 60%. With SSP1-2.6, however, the changes are much smaller with SH area declining by about 25% and NH increasing by about 10%. The results suggest substantial restructuring of global production for these crops. Essentially, climate change shifts temperature-suitable locations toward higher latitudes. In the SH, most of the historically suitable areas were already at the southern end of the landmass limiting opportunities for adaptation. If breeding efforts can bring chilling requirements for the major cultivars closer to that currently seen in some cultivars, suitable areas at the end of the century are greater, but higher summer temperatures offset the extent. The high value of fruit crops provides adaptation opportunities such as cultivar selection, canopy cooling using sprinklers, shade netting, and precision irrigation.

Assuntos

RESUMO

This study determined the meteorological variable that most contribute to the productivity of sugarcane stalks in the northwest and central regions of Rio Grande do Sul. The following sugarcane genotypes were used: UFSM XIKA FW, UFSM LUCI FW, UFSM PRETA FW, UFSM DINA FW, UFSM MARI FW, and IAC87-3396. The UFSM cultivars originate from a mutation process in the breeding program conducted at the Federal University of Santa Maria, Frederico Westphalen campus, and have low temperature tolerance. The productivity-associated morphological characters included in the models were average stem diameter, average stem number per meter of furrow, and average stem height. The following meteorological variables were used: minimum air temperature, precipitation, incident solar radiation, and accumulated thermal sum. Pearson’s correlation, canonical correlations, and Stepwise regression were performed between morphological characters and meteorological variables: minimum air temperature had the greatest influence on sugarcane productivity in the studied regions, and accumulated thermal sum showed the highest correlation and contributed most to stem diameter and average stem height. Thus, the models indicated that the growth of sugarcane is positively associated with the accumulated thermal sum, and sugarcane can be cultivated at the studied regions.

O objetivo deste trabalho foi determinar a variável meteorológica com maior contribuição na produtividade de colmos de cana-de-açúcar na região noroeste e central do Rio Grande do Sul. Os genótipos de cana-de-açúcar utilizados foram: UFSM XIKA FW, UFSM LUCI FW, UFSM PRETA FW, UFSM DINA FW, UFSM MARI FW, IAC87-3396. As cultivares UFSM são provenientes do processo de mutação do programa de melhoramento da Universidade Federal de Santa Maria, campus de Frederico Westphalen, e possuem tolerância a baixas temperaturas. Os caracteres morfológicos responsáveis pela produtividade utilizados nos modelos foram diâmetro médio de colmo, número médio de colmos por metro de sulco e estatura média de colmos. As variáveis meteorológicas utilizadas foram a temperatura mínima do ar, precipitação pluviométrica, radiação solar incidente e soma térmica acumulada. Foi realizada a correlação de Pearson, correlações canônicas e regressão de Stepwise entre os caracteres morfológicos e as variáveis meteorológicas, nos quais foi constado que a temperatura mínima do ar é a variável com maior influência na produtividade da cana-de-açúcar nas regiões estudadas e, que a soma térmica acumulada é a variável com maior correlação e contribuição no diâmetro de colmo e estatura média dos colmos. Desse modo, os modelos indicam que o crescimento da cana-de-açúcar responde de forma positiva a soma térmica acumulada, e as regiões em estudo apresentam potencial para o cultivo da cana-de-açúcar.

Assuntos

RESUMO

This study determined the meteorological variable that most contribute to the productivity of sugarcane stalks in the northwest and central regions of Rio Grande do Sul. The following sugarcane genotypes were used: UFSM XIKA FW, UFSM LUCI FW, UFSM PRETA FW, UFSM DINA FW, UFSM MARI FW, and IAC87-3396. The UFSM cultivars originate from a mutation process in the breeding program conducted at the Federal University of Santa Maria, Frederico Westphalen campus, and have low temperature tolerance. The productivity-associated morphological characters included in the models were average stem diameter, average stem number per meter of furrow, and average stem height. The following meteorological variables were used: minimum air temperature, precipitation, incident solar radiation, and accumulated thermal sum. Pearsons correlation, canonical correlations, and Stepwise regression were performed between morphological characters and meteorological variables: minimum air temperature had the greatest influence on sugarcane productivity in the studied regions, and accumulated thermal sum showed the highest correlation and contributed most to stem diameter and average stem height. Thus, the models indicated that the growth of sugarcane is positively associated with the accumulated thermal sum, and sugarcane can be cultivated at the studied regions.(AU)

O objetivo deste trabalho foi determinar a variável meteorológica com maior contribuição na produtividade de colmos de cana-de-açúcar na região noroeste e central do Rio Grande do Sul. Os genótipos de cana-de-açúcar utilizados foram: UFSM XIKA FW, UFSM LUCI FW, UFSM PRETA FW, UFSM DINA FW, UFSM MARI FW, IAC87-3396. As cultivares UFSM são provenientes do processo de mutação do programa de melhoramento da Universidade Federal de Santa Maria, campus de Frederico Westphalen, e possuem tolerância a baixas temperaturas. Os caracteres morfológicos responsáveis pela produtividade utilizados nos modelos foram diâmetro médio de colmo, número médio de colmos por metro de sulco e estatura média de colmos. As variáveis meteorológicas utilizadas foram a temperatura mínima do ar, precipitação pluviométrica, radiação solar incidente e soma térmica acumulada. Foi realizada a correlação de Pearson, correlações canônicas e regressão de Stepwise entre os caracteres morfológicos e as variáveis meteorológicas, nos quais foi constado que a temperatura mínima do ar é a variável com maior influência na produtividade da cana-de-açúcar nas regiões estudadas e, que a soma térmica acumulada é a variável com maior correlação e contribuição no diâmetro de colmo e estatura média dos colmos. Desse modo, os modelos indicam que o crescimento da cana-de-açúcar responde de forma positiva a soma térmica acumulada, e as regiões em estudo apresentam potencial para o cultivo da cana-de-açúcar.(AU)

Assuntos

RESUMO

ABSTRACT: This study determined the meteorological variable that most contribute to the productivity of sugarcane stalks in the northwest and central regions of Rio Grande do Sul. The following sugarcane genotypes were used: UFSM XIKA FW, UFSM LUCI FW, UFSM PRETA FW, UFSM DINA FW, UFSM MARI FW, and IAC87-3396. The UFSM cultivars originate from a mutation process in the breeding program conducted at the Federal University of Santa Maria, Frederico Westphalen campus, and have low temperature tolerance. The productivity-associated morphological characters included in the models were average stem diameter, average stem number per meter of furrow, and average stem height. The following meteorological variables were used: minimum air temperature, precipitation, incident solar radiation, and accumulated thermal sum. Pearson's correlation, canonical correlations, and Stepwise regression were performed between morphological characters and meteorological variables: minimum air temperature had the greatest influence on sugarcane productivity in the studied regions, and accumulated thermal sum showed the highest correlation and contributed most to stem diameter and average stem height. Thus, the models indicated that the growth of sugarcane is positively associated with the accumulated thermal sum, and sugarcane can be cultivated at the studied regions.

RESUMO: O objetivo deste trabalho foi determinar a variável meteorológica com maior contribuição na produtividade de colmos de cana-de-açúcar na região noroeste e central do Rio Grande do Sul. Os genótipos de cana-de-açúcar utilizados foram: UFSM XIKA FW, UFSM LUCI FW, UFSM PRETA FW, UFSM DINA FW, UFSM MARI FW, IAC87-3396. As cultivares UFSM são provenientes do processo de mutação do programa de melhoramento da Universidade Federal de Santa Maria, campus de Frederico Westphalen, e possuem tolerância a baixas temperaturas. Os caracteres morfológicos responsáveis pela produtividade utilizados nos modelos foram diâmetro médio de colmo, número médio de colmos por metro de sulco e estatura média de colmos. As variáveis meteorológicas utilizadas foram a temperatura mínima do ar, precipitação pluviométrica, radiação solar incidente e soma térmica acumulada. Foi realizada a correlação de Pearson, correlações canônicas e regressão de Stepwise entre os caracteres morfológicos e as variáveis meteorológicas, nos quais foi constado que a temperatura mínima do ar é a variável com maior influência na produtividade da cana-de-açúcar nas regiões estudadas e, que a soma térmica acumulada é a variável com maior correlação e contribuição no diâmetro de colmo e estatura média dos colmos. Desse modo, os modelos indicam que o crescimento da cana-de-açúcar responde de forma positiva a soma térmica acumulada, e as regiões em estudo apresentam potencial para o cultivo da cana-de-açúcar.

RESUMO

Seasonal development, cumulative growing degree-days (CUMDD10), and population density of Lycorma delicatula (White) were studied through weekly sampling of 30 plants (5 plants/species, 3 common plus 3 site-specific species per site) at six sites in Pennsylvania in 2019. In total, 24,159 L. delicatula (1,987 egg masses, 1,068 first instars, 239 second instars, 153 third instars, 410 fourth instars, and 20,302 adults) were recorded in 28 wk. Seasonal development followed similar pattern at all sites despite differences in starting, peaking, and ending time for specific life stages. The average CUMDD10 requirement for the onset of the first instars, second instars, third instars, fourth instars, adults, and eggs was 270, 465, 645, 825, 1,112, and 1,825, respectively. Population density ranged from 0 to 207.4, 0-298.9, and 0-9.6/m2 for nymphs, adults, and egg masses, respectively. Significant difference in population density was found between sites, hosts/substrates, and sampling weeks. Favored oviposition substrates included tree-of-heaven and black birch despite egg masses being laid on many other surfaces. Nymphs fed on different hosts in early stages but preferred American beech, tree-of-heaven, black birch, and multiflora rose. Adults were predominately found on tree-of-heaven with preoviposition surge on black birch and red maple. Sizable nymph and adult populations persisted on summer grape throughout the season. Tree-of-heaven played an irreplaceable role in the seasonal development and life history of L. delicatula in the field. Survey and detection activities should focus on tree-of-heaven with management efforts directed to aggregating adults for maximum efficacy.

Assuntos

RESUMO

Climate change has profound environmental and socio-economic implications. To analyze climate change in relation to crops, a wide variety of agro-climatic indices has been proposed by the scientific community. In this study, changes in a set of 12 agro-climatic indices related to temperature were investigated in Central Chile over a 56-year period (1961-2016). The indices were computed based on data referring to daily maximum and minimum temperatures (TX and TN). They were organized in two categories: (1) cold- and (2) heat-related indices. Cold-related indices consisted of first frost day (FFD), last frost day (LFD), frost period (FP), number of frost days (FD), accumulated frost (AF), and number of days when TN is below - 2 °C (FD-2). Heat-related indices included the growing degree day (GDD) index, calculated based on four thresholds which measure the available heat resources for a wide variety of plants with different thermal requirements, and two heat stress indices which quantify the number of days with TX above 25 °C (plant heat stress (PHS)) and above 30 °C (plant high heat stress (PHHS)). Changes in agro-climatic indices were investigated using the Mann-Kendall test and the Sen's slope estimator. The main results revealed that the FFD occurred later, while LFD occurred earlier, thus determining a shortening of the FP in the northern half of the studied area. Trends in FD, AF, and FD-2 indices generally indicated warmer conditions in terms of TN during the cold period of the year. Agro-climatic indices related to heat showed important changes in Central Chile. Thus, statistically, the majority of trends become significant and indicated enhanced condition for crops in respect of GDD indices. However, from the heat stress perspective, the analyzed indices showed that conditions become worse in most of the studied locations for crops sensible to temperatures higher than 25 and 30 °C.

Assuntos

RESUMO

Este estudo objetivou avaliar a temperatura-base inferior (Tb), soma térmica e fenologia de cultivares de videira e de quivizeiro. Estacas com 25-35 cm das cultivares de videira Chardonnay (CH), Isabel (IS), Niágara Branca (NB), Concord (CO) e Bordô (BO) e de quivizeiro Bruno (BR), Monty (MO), Elmwood (EL), MG06 (MG) e Yellow Queen (YQ) foram coletadas em pomares localizados em Veranópolis, RS, em 03/06/2015. As estacas intactas foram submetidas a 0 °C por 1.008 Horas de Frio (HF), em câmaras incubadoras para a superação da dormência, embaladas em filme plástico preto. Na sequência, foram transferidas para as temperaturas de 4, 6, 8, 10 e 12 °C, em estacas de nós-isolados, plantadas em espuma fenólica. Durante 150 dias, as gemas foram avaliadas a cada 2-3 dias quanto à brotação, no estádio de ponta verde e seus dados (1/dias para brotação) inseridos em curvas de regressão para estimativa da Tb para cada genótipo. Séries históricas de fenologia de 10 anos das cultivares e dados meteorológicos dos locais de cultivo foram utilizados para o cálculo da soma térmica (graus-dia) das frutíferas durante o ciclo vegetativo. A Tb se diferenciou entre as espécies frutíferas. A Tb foi menor para cultivares de quivizeiro (BR=3,0 °C; MO=3,3 ºC; EL=3,1 °C; MG=3,2 °C e YQ=3,0 °C) e maior para cultivares de videira (CH=4,2 °C; IS=4,3 °C; NB=4,1 °C; CO=6,2 °C e BO=4,4 °C). A soma de graus-dia (GD) variou de 1670,9 a 2060,7 para as cultivares de videira e de 3179,6 a 3762,0 para as cultivares de quivizeiro. A maior soma de GD para a cultura do quivizeiro é dada pelo maior número de dias do seu ciclo vegetativo associada a menor Tb dos genótipos, se comparada à cultura da videira. O subperíodo fenológico (brotação à maturação) das frutíferas, em 100% dos casos, respondeu mais ao tempo térmico (graus-dia) do que ao tempo cronológico (dias) para completar o ciclo vegetativo.

This study aimed to evaluate the lower base temperature (Tb), thermal time and grapevine phenology and kiwi cultivars. Twigs 25-35-cm long for the following cultivars: grapevine, Chardonnay (CH), Isabel (IS), Niágara Branca (NB), Concord (CO) and Bordô (BO); and kiwi, Bruno (BR), Monty (MO), Elmwood (EL), MG06 (MG) and Yellow Queen (YQ) were collected in orchards in Veranópolis, RS State, on 06/03/2015. Intact twigs packed in black plastic film were subjected to 1,008 chilling hours (HC) at 0°C in incubators to overcome dormancy and then transferred to temperatures of 4, 6, 8, 10, and 12°C on single-node cuttings planted in phenolic foam. Over 150 d, budburst of the buds was evaluated in 2-3-d intervals in the green-tip stage. The resulted inverse data for number of days to budburst (1/days to budburst) was inserted into regression curves to estimate Tb for each genotype. Historical phonological series comprised of 10-years for the analyzed cultivars and meteorological data of the cultivation sites were used to determine thermal time (degree-days) for the fruit trees during the growing season. Temperate fruit species exhibited different Tb. Tb was lower for kiwi cultivars (BR=3,0°C; MO=3,3ºC; EL=3,1°C; MG=3,2°C and YQ=3°C) and higher for grapevine cultivars (CH=4,2°C; IS=4,3°C; NB=4,1°C; CO=6,2°C; and BO=4,4°C). The thermal time, in degree-days (DD), varied from 1670.9 to 2060.7 for grapevine cultivars and from 3179.6 to 3762.0 for kiwi cultivars. The higher DD sum for kiwi crop was given by the higher number of days of its vegetative cycle associated to lower Tb of the genotypes, when compared to the grapevine crop. The phenological subperiod (budburst to maturation) of the fruit trees in 100% of the assessed cases responded more to thermal time (degree-days) than to chronological time (d) to complete the vegetative cycle.

Assuntos

RESUMO

This study analyzed the behavior of the annual ryegrass (Lolium multiflorum) BRS Ponteio and dual-purpose wheat (Triticum aestivum) BRS Tarumã with different doses of ammonium sulfate as topdressing and evaluated the exponential growth model to explain the physiological development of both species. For each species, a completely randomized design was used with four replications per treatment with 9m2 area, in which the following treatments were distributed: 0, 150, 250, 350 and 450 kg nitrogen per hectare applied as ammonium sulfate. The cumulative and adjusted productions to the exponential growth model at the end of the cycle were, respectively: BRS Ponteio 150 = 5,620; 250 = 5,920; 350 = 7,585 and 450 = 8,491 and BRS Tarumã 150 = 3,922; 250 = 5,060; 350 = 7,024 and 450 = 7,491 kg dry matter per hectare. The cultivars analyzed without nitrogen application had limited growth and showed no adjustment even to the first order linear model. The application of nitrogen decreased the interval between cuts and increased dry matter production per hectare following the exponential growth model.

Assuntos

RESUMO

This study analyzed the behavior of the annual ryegrass (Lolium multiflorum) BRS Ponteio and dual-purpose wheat (Triticum aestivum) BRS Tarumã with different doses of ammonium sulfate as topdressing and evaluated the exponential growth model to explain the physiological development of both species. For each species, a completely randomized design was used with four replications per treatment with 9m2 area, in which the following treatments were distributed: 0, 150, 250, 350 and 450 kg nitrogen per hectare applied as ammonium sulfate. The cumulative and adjusted productions to the exponential growth model at the end of the cycle were, respectively: BRS Ponteio 150 = 5,620; 250 = 5,920; 350 = 7,585 and 450 = 8,491 and BRS Tarumã 150 = 3,922; 250 = 5,060; 350 = 7,024 and 450 = 7,491 kg dry matter per hectare. The cultivars analyzed without nitrogen application had limited growth and showed no adjustment even to the first order linear model. The application of nitrogen decreased the interval between cuts and increased dry matter production per hectare following the exponential growth model.(AU)

Assuntos

RESUMO

The objective of this study was to assess the growth of annual ryegrass (Lolium multiflorum) cv. BRS Ponteio with different doses of nitrogen applied in the pasture, thereby adjusting their growth to the exponential growth model. A randomized block design was used with five nitrogen application rates (0, 150, 250, 350, and 450 kg N ha-1) and four replicates, applied in installments. Each plot measured 9 m2. On April 15, 2014, 25 kg ha-1 of viable pure seeds of annual ryegrass were sown at a depth of 0.02 m, in 18 rows spaced at 0.17 m in each plot. Growth in the control treatment (zero nitrogen) pasture lasted 167 days with only three cuts, whereas in pastures treated with 350 and 450 kg N ha-1, growth was extended for an additional 45 days with a 333% increase in the number of cuts. The pastures were used for the same duration (188 days) in the treatments with 150 and 250 kg N ha-1, however, increased nitrogen resulted in two additional cuts and a shorter time interval between cuts. The time interval between each cut and the degree-days interacted dynamically causing distinct growth. Growth of the annual ryegrass BRS Ponteio without nitrogen application is poor and cannot be represented even by a first order linear model. The application of nitrogen topdressing, in the form of urea, decreases the time interval between cuts, increases the dry matter production per hectare, stimulates this production, and follows the exponential growth model.(AU)

Objetivou-se estudar a produção da cultura de azevém anual (Lolium multiflorum) BRS Ponteio com diferentes doses de nitrogênio aplicadas em cobertura ajustando-as ao modelo de crescimento exponencial. Foi utilizado delineamento completamente casualizado com quatro repetições por tratamentos com parcelas de 9m2 de área útil, nas quais foram distribuídos os tratamentos: 0, 150, 250, 350 e 450 quilogramas de nitrogênio por hectare aplicados de forma parcelada. No dia 15 de abril de 2014 realizou-se a semeadura do azevém na densidade de 25 kg de sementes puras viáveis ha-1 na profundidade de 0,02 m, com 18 linhas em cada parcela espaçadas 0,17 m. No tratamento testemunha (zero de nitrogênio) o pasto durou 167 dias com apenas três cortes, enquanto nas doses de 350 e 450 kg de nitrogênio por hectare a espécie estendeu-se por mais 45 dias com número de cortes 333% maior. Nos tratamentos 150 e 250 quilogramas de nitrogênio por hectare verificou-se que o tempo de utilização da pastagem foi o mesmo, 188 dias, mas houve diferença de dois cortes, ou seja, as diferentes doses de nitrogênio impactam sobre os intervalos entre cortes. O intervalo de dias entre cada corte e os graus-dia interagem de forma dinâmica ocasionando crescimento distintos. O cultivo de azevém anual BRS Ponteio sem aplicação de nitrogênio é limitado e não apresenta ajuste nem mesmo a modelo linear de primeira ordem. A aplicação de nitrogênio em cobertura na forma de ureia diminui o intervalo entre cortes e aumenta a produção de matéria seca por hectare. A aplicação de nitrogênio em cobertura na forma de ureia estimula a produção de matéria seca, seguindo o modelo de crescimento exponencial.(AU)

Assuntos

RESUMO

Este estudo objetivou avaliar a temperatura-base inferior (Tb), soma térmica e fenologia de cultivares de videira e de quivizeiro. Estacas com 25-35 cm das cultivares de videira Chardonnay (CH), Isabel (IS), Niágara Branca (NB), Concord (CO) e Bordô (BO) e de quivizeiro Bruno (BR), Monty (MO), Elmwood (EL), MG06 (MG) e Yellow Queen (YQ) foram coletadas em pomares localizados em Veranópolis, RS, em 03/06/2015. As estacas intactas foram submetidas a 0 °C por 1.008 Horas de Frio (HF), em câmaras incubadoras para a superação da dormência, embaladas em filme plástico preto. Na sequência, foram transferidas para as temperaturas de 4, 6, 8, 10 e 12 °C, em estacas de nós-isolados, plantadas em espuma fenólica. Durante 150 dias, as gemas foram avaliadas a cada 2-3 dias quanto à brotação, no estádio de ponta verde e seus dados (1/dias para brotação) inseridos em curvas de regressão para estimativa da Tb para cada genótipo. Séries históricas de fenologia de 10 anos das cultivares e dados meteorológicos dos locais de cultivo foram utilizados para o cálculo da soma térmica (graus-dia) das frutíferas durante o ciclo vegetativo. A Tb se diferenciou entre as espécies frutíferas. A Tb foi menor para cultivares de quivizeiro (BR=3,0 °C; MO=3,3 ºC; EL=3,1 °C; MG=3,2 °C e YQ=3,0 °C) e maior para cultivares de videira (CH=4,2 °C; IS=4,3 °C; NB=4,1 °C; CO=6,2 °C e BO=4,4 °C). A soma de graus-dia (GD) variou de 1670,9 a 2060,7 para as cultivares de videira e de 3179,6 a 3762,0 para as cultivares de quivizeiro. A maior soma de GD para a cultura do quivizeiro é dada pelo maior número de dias do seu ciclo vegetativo associada a menor Tb dos genótipos, se comparada à cultura da videira. O subperíodo fenológico (brotação à maturação) das frutíferas, em 100% dos casos, respondeu mais ao tempo térmico (graus-dia) do que ao tempo cronológico (dias) para completar o ciclo vegetativo.(AU)

This study aimed to evaluate the lower base temperature (Tb), thermal time and grapevine phenology and kiwi cultivars. Twigs 25-35-cm long for the following cultivars: grapevine, Chardonnay (CH), Isabel (IS), Niágara Branca (NB), Concord (CO) and Bordô (BO); and kiwi, Bruno (BR), Monty (MO), Elmwood (EL), MG06 (MG) and Yellow Queen (YQ) were collected in orchards in Veranópolis, RS State, on 06/03/2015. Intact twigs packed in black plastic film were subjected to 1,008 chilling hours (HC) at 0°C in incubators to overcome dormancy and then transferred to temperatures of 4, 6, 8, 10, and 12°C on single-node cuttings planted in phenolic foam. Over 150 d, budburst of the buds was evaluated in 2-3-d intervals in the green-tip stage. The resulted inverse data for number of days to budburst (1/days to budburst) was inserted into regression curves to estimate Tb for each genotype. Historical phonological series comprised of 10-years for the analyzed cultivars and meteorological data of the cultivation sites were used to determine thermal time (degree-days) for the fruit trees during the growing season. Temperate fruit species exhibited different Tb. Tb was lower for kiwi cultivars (BR=3,0°C; MO=3,3ºC; EL=3,1°C; MG=3,2°C and YQ=3°C) and higher for grapevine cultivars (CH=4,2°C; IS=4,3°C; NB=4,1°C; CO=6,2°C; and BO=4,4°C). The thermal time, in degree-days (DD), varied from 1670.9 to 2060.7 for grapevine cultivars and from 3179.6 to 3762.0 for kiwi cultivars. The higher DD sum for kiwi crop was given by the higher number of days of its vegetative cycle associated to lower Tb of the genotypes, when compared to the grapevine crop. The phenological subperiod (budburst to maturation) of the fruit trees in 100% of the assessed cases responded more to thermal time (degree-days) than to chronological time (d) to complete the vegetative cycle.(AU)

Assuntos

RESUMO

The objective of this study was to assess the growth of annual ryegrass (Lolium multiflorum) cv. BRS Ponteio with different doses of nitrogen applied in the pasture, thereby adjusting their growth to the exponential growth model. A randomized block design was used with five nitrogen application rates (0, 150, 250, 350, and 450 kg N ha-1) and four replicates, applied in installments. Each plot measured 9 m2. On April 15, 2014, 25 kg ha-1 of viable pure seeds of annual ryegrass were sown at a depth of 0.02 m, in 18 rows spaced at 0.17 m in each plot. Growth in the control treatment (zero nitrogen) pasture lasted 167 days with only three cuts, whereas in pastures treated with 350 and 450 kg N ha-1, growth was extended for an additional 45 days with a 333% increase in the number of cuts. The pastures were used for the same duration (188 days) in the treatments with 150 and 250 kg N ha-1, however, increased nitrogen resulted in two additional cuts and a shorter time interval between cuts. The time interval between each cut and the degree-days interacted dynamically causing distinct growth. Growth of the annual ryegrass BRS Ponteio without nitrogen application is poor and cannot be represented even by a first order linear model. The application of nitrogen topdressing, in the form of urea, decreases the time interval between cuts, increases the dry matter production per hectare, stimulates this production, and follows the exponential growth model.

Objetivou-se estudar a produção da cultura de azevém anual (Lolium multiflorum) BRS Ponteio com diferentes doses de nitrogênio aplicadas em cobertura ajustando-as ao modelo de crescimento exponencial. Foi utilizado delineamento completamente casualizado com quatro repetições por tratamentos com parcelas de 9m2 de área útil, nas quais foram distribuídos os tratamentos: 0, 150, 250, 350 e 450 quilogramas de nitrogênio por hectare aplicados de forma parcelada. No dia 15 de abril de 2014 realizou-se a semeadura do azevém na densidade de 25 kg de sementes puras viáveis ha-1 na profundidade de 0,02 m, com 18 linhas em cada parcela espaçadas 0,17 m. No tratamento testemunha (zero de nitrogênio) o pasto durou 167 dias com apenas três cortes, enquanto nas doses de 350 e 450 kg de nitrogênio por hectare a espécie estendeu-se por mais 45 dias com número de cortes 333% maior. Nos tratamentos 150 e 250 quilogramas de nitrogênio por hectare verificou-se que o tempo de utilização da pastagem foi o mesmo, 188 dias, mas houve diferença de dois cortes, ou seja, as diferentes doses de nitrogênio impactam sobre os intervalos entre cortes. O intervalo de dias entre cada corte e os graus-dia interagem de forma dinâmica ocasionando crescimento distintos. O cultivo de azevém anual BRS Ponteio sem aplicação de nitrogênio é limitado e não apresenta ajuste nem mesmo a modelo linear de primeira ordem. A aplicação de nitrogênio em cobertura na forma de ureia diminui o intervalo entre cortes e aumenta a produção de matéria seca por hectare. A aplicação de nitrogênio em cobertura na forma de ureia estimula a produção de matéria seca, seguindo o modelo de crescimento exponencial.

Assuntos

RESUMO

Thermal time models may describe and compare seed germination, providing information useful to explain species distribution. However, the capacity of such threshold models to describe germination of tropical native species has been less studied. We evaluated seed germination of a legume tree species (Peltophorum dubium), typical from South American seasonal forests, as described by two linear thermal time models: probit model and graphic model. Seeds were provided from four different provenances in a latitudinal gradient in Brazil, and their physical dormancy mechanically released before the trials. Graphic model and probit regression were used to determine thermal parameters (cardinal temperatures and thermal time requirement) on sub- and supra-optimal ranges for the different seed provenances. Germination rate mainly followed linear relationship with temperature, and regression lines of different germination fractions converged base temperature in the x-axis. Therefore, probit model assumed a single-value of base temperature in the sub-optimal range and a normal distribution of thermal time. Base temperature tended to be higher in the Northern provenance, Porto Velho, showing slower germination under cooler temperatures. Supra-optimal temperatures have shown similar thermal time requirements and different values for ceiling temperature, according to model predictions. No clear patterns have been found between seed provenances and thermal time requirement. Both probit and graphic models have provided reasonable predictions of germination times (t10 and t50), except under the coolest temperatures. Probit regression always described at least 70% of seed germination. Thermal time assumptions, linear models applicability and their limitations are discussed.

Assuntos

RESUMO

Climate, soil and management are the main drives for growth and production of tropical pastures. Thus, a better understanding of the effects of these factors and their interactions under climate conditions is required to obtain effective management options. Here, we used data from two field trials to research on climate and management interactions on the production seasonality of Panicum maximum Jacq. Treatments included four sampling times (250, 500, 750, and 1000 °C accumulated) during eight regrowth period, under irrigated and rainfed conditions and, cuts were made to simulate grazing intensity. All treatments were arranged in a completely randomized block design with four replications. At each sampling time, basal tillers were sampled to observe meristematic differentiation and were linked with the respective daylength. Soil moisture was determined, and the water availability index (WAI) was calculated. The dry matter production (DMP) was taken and relative productivity was calculated. Soil moisture was the key seasonal drive in spring-summer and the WAI could be used to adjust the maximum production for that season. The major drive for DMP in fall was the daylength, which was found at 11.81 h. For all seasons, DMP correlated better with the residues in early regrowth phase (r = 0.82 and p < 0.0001) and with degree-days at final regrowth phase (r = 0.73 p < 0.01). Applying these critical values to management guidelines should make Guinea grass DMP more efficient on tropical farms.

Assuntos

RESUMO

Climate, soil and management are the main drives for growth and production of tropical pastures. Thus, a better understanding of the effects of these factors and their interactions under climate conditions is required to obtain effective management options. Here, we used data from two field trials to research on climate and management interactions on the production seasonality of Panicum maximum Jacq. Treatments included four sampling times (250, 500, 750, and 1000 °C accumulated) during eight regrowth period, under irrigated and rainfed conditions and, cuts were made to simulate grazing intensity. All treatments were arranged in a completely randomized block design with four replications. At each sampling time, basal tillers were sampled to observe meristematic differentiation and were linked with the respective daylength. Soil moisture was determined, and the water availability index (WAI) was calculated. The dry matter production (DMP) was taken and relative productivity was calculated. Soil moisture was the key seasonal drive in spring-summer and the WAI could be used to adjust the maximum production for that season. The major drive for DMP in fall was the daylength, which was found at 11.81 h. For all seasons, DMP correlated better with the residues in early regrowth phase (r = 0.82 and p < 0.0001) and with degree-days at final regrowth phase (r = 0.73 p < 0.01). Applying these critical values to management guidelines should make Guinea grass DMP more efficient on tropical farms.(AU)

Assuntos

RESUMO

Fopius arisanus (Sonan) is a solitary parasitoid of eggs and the first instar larvae of Tephritidae. Due to the occurrence of Ceratitis capitata (Wiedemann) in various regions and under several climatic conditions, this study aimed to evaluate the effect of different temperatures on the embryonic development (egg-adult) and determine thermal requirements and the number of annual generations F. arisanus on eggs of C. capitata. In the laboratory, eggs of C. capitata (24 h) were submitted to parasitism of F. arisanus during 6 h. Later, the eggs were placed in plastic containers (50 mL) (50 eggs/container) on a layer of artificial diet and packed in chambers at temperatures 15, 18, 20, 22, 25, 28, 30, and 32 ± 1°C, RH 70 ± 10%, and a photophase of 12 h. The largest number of offspring, emergence rate, and weight of adults of F. arisanus were observed at 25°C. The highest sex ratios (sr > 0.75) were recorded at 15 and 18°C, being statistically higher than the temperatures 20°C (0.65), 22°C (0.64), 25°C (0.65), 28°C (0.49), and 30°C (0.47). At 32°C, there was no embryonic development of F. arisanus. The egg-adult period was inversely proportional to temperature. Based on the development of the biological cycle (egg-adult), the temperature threshold (T t) was 10.3°C and thermal constant (K) of 488.34 degree-days, being the number of generations/year directly proportional to the temperature increase. The data show the ability of F. arisanus to adapt to different thermal conditions, which is important for biological control programs of C. capitata.

Assuntos

RESUMO

ABSTRACT The phenological growth stages of various species of monocotyledonous and dicotyledonous plants can be uniformly coded using the Biologische Bundesanstalt, Bundessortenamt, und Chemische Industrie (BBCH) scale. The aim of the present study was to determine the duration of different phenological stages and the temperature requirements of the sugar-apple, Annona squamosa, during two crop cycles in the semiarid region of Brazil. Phenological stages were divided into eight of ten possible principal stages: (0) bud development, (1) leaf development, (3) shoot/branch development, (5) inflorescence emergence, (6) flowering, (7) fruit development, (8) fruit maturity and (9) senescence and the beginning of dormancy. The phenological cycle of the sugar-apple from having closed leaf buds to the fruit ripening stage lasted 149 and 164 days with temperature requirements of 1684.5 and 1786.7 degree days (DD) for the first and second crop cycles, respectively. The results provided important information that will inform the correct timing for crop management practices.

Assuntos

RESUMO

To complete each phase of the growing season, plants must accumulate thermal time at lower base temperature (Tb). Little information exists on Tb variation between either fruit species or cultivars of the same species. We therefore aimed to determine the lower base temperature for contrasting genotypes in precocity of peach, plum, grape, pear, and kiwi. Twigs 25-35 cm long for the following cultivars: peach, Tropic Beauty (TB) and Eragil (ER); plum, Gulf Blaze (GB) and Letícia (LE); grape, Chardonnay (CH) and Cabernet Sauvignon (CS); pear, Smith (SM) and Packhams (PA); and kiwi, Golden King (GK) and Hayward (HA) were collected in orchards in Veranópolis, RS Estate, on 06/13/2014, with 0 h at temperatures ? 7.2C (chilling hours; HC) in the field. Intact twigs packed in black plastic film were subjected to 1,008 HC at 0C in incubators to overcome dormancy and then transferred to temperatures of 2, 4, 6, 8, 10, and 12C on single-node cuttings planted in phenolic foam to define effective heat temperature for the genotypes. Over 110 d, budburst of the buds was evaluated in 2-3-d intervals in the green-tip stage. The resulting inverse data of number of days to budburst (1/days to budburst) was inserted into regression curves to estimate Tb for each genotype. Historical phonological series comprised of 10 years for the analyzed cultivars and meteorological data of the cultivation

Para completar cada subperíodo do ciclo vegetativo, as plantas necessitam de uma soma térmica acumulada a partir da temperatura-base inferior (Tb). Há pouca informação que mostre variação da Tb, considerando espécies e cultivares de uma mesma espécie frutífera. O objetivo deste estudo foi determinar a temperatura-base inferior para genótipos contrastantes em precocidade de pessegueiro, ameixeira, videira, pereira e quivizeiro. Estacas com 25-35 cm de comprimento das cultivares de pessegueiro Tropic Beauty (TB) e Eragil (ER), de ameixeira Gulf Blaze (GB) e Letícia (LE); de videira Chardonnay (CH) e Cabernet Sauvignon (CS), de pereira Smith (SM) e Packhams (PA) e de quivizeiro Golden King (GK) e Hayward (HA) foram coletadas em pomares localizados no município de Veranópolis, RS, em 13/06/2014, com zero horas de frio ? 7,2C (HF) a campo. As estacas intactas foram submetidas a 0C por 1.008 HF, em câmaras incubadoras para a superação da dormência, embaladas em filme plástico preto. Na sequência, foram transferidas para as temperaturas de 2, 4, 6, 8, 10 e 12C, em estacas de nós-isolados, plantadas em espuma fenólica. Durante 110 dias, as gemas foram avaliadas a cada 2-3 dias quanto à brotação, no estádio de ponta verde, e os dados do inverso do número de dias para brotação (1/dias para brotação) inseridos em curvas de regressão para estimativa da Tb para cada