Melhora na predição do aparecimento de folhas em batata cultivada a campo

The calculation of leaf appearance rate (LAR) and number of accumulated or emerged leaves (NL) on the main stem are part of many crop simulation models. The purpose of this study was to adapt and evaluate a model (WE model) for simulating the main stem LAR and NL in potato (Solanum tuberosum L.). The WE model is a non-linear multiplicative model that takes into account the effect of genotype and environmental factors on LAR. A linear model (Phyllochron model) was also used as a comparison with the WE model. A series of field experiments with 14 planting dates over two years (2003 and 2004) was carried out in Santa Maria, RS, Brazil, using the cultivar Asterix. Coefficients of the WE model and the phyllochron model were estimated with data from four planting dates in 2003, and the models were validated with data from the other ten plantings, which are independent data. The statistics used to quantify model performance was the root mean square error (RMSE). The WE model was a better predictor of NL (RMSE=2.0 leaves) than the phyllochron model (RMSE=3.7 leaves). The WE model has coefficients with biological meaning and a non-linear temperature response function, which renders generality and robustness to this LAR model.O cálculo da taxa de aparecimento de folhas (LAR) e do número de folhas acumuladas ou emergidas (NL) na haste principal são parte de muitos modelos de simulação de cultivos agrícolas. O objetivo deste estudo foi adaptar e avaliar um modelo (modelo WE) para simular a LAR e o NL na haste principal de batata (Solanum tuberosum L.). O modelo WE é um modelo multiplicativo não linear que leva em conta o efeito do genótipo e de fatores ambientais sobre LAR. Um modelo linear (modelo do filocrono) também foi usado como comparação com o modelo WE. Uma série de experimentos de campo com 14 épocas de plantio durante dois anos (2003 e 2004) foi conduzido em Santa Maria, RS. A cultivar usada foi Asterix. Os coeficientes dos modelos WE e filocrono foram estimados com dados de quarto épocas de plantio em 2003 e os modelos foram avaliados com dados independentes de outras dez épocas de plantio. A estatística usada para quantificar o desempenho dos dois modelos foi a raiz do quadrado médio do erro (RMSE). O modelo WE foi um melhor preditor de NL (RMSE=2,0 folhas) do que o modelo filocrono (RMSE=3,7 folhas). O modelo WE tem coeficientes com significado biológico e uma função não linear de resposta a temperatura que conferem generalidade e robustes a este modelo de LAR

Yield of chamomile capitula and essential oil in competition with weeds in different spacings and sowing dates

Chamomile is an important socioeconomic option for family farming. The crop involves manual management practices and restriction to the use of herbicides, and the knowledge regarding the interference of weeds on the yield of chamomile capitula and quality of the essential oil is still limited. In this perspective, this study aimed to assess the effect of sowing dates, plant spacings and hoeing management on the yield of capitula, content, and yield of essential oil in the environmental conditions of a region with Humid Subtropical climate without defined seasons. The experiments were conducted on four dates (18/03, 28/04, 31/06, and 30/08/2017), with plants spaced by 0.05, 0.10, 0.15, 0.20, 0.30, and 0.40 m within rows. On March 28 and May 14, 2018, the plant spacings between plants in the row were 0.05, 0.10, 0.15, and 0.20 m, including two hoeing managements (with and without weeds). The variables analyzed in the two years were the yield of dry capitula, the dry mass of chamomile plants and weeds (g m-²), and the content and yield of essential oil in 2018. The sowing dates influenced the yield of floral capitula, the content, and yield of essential oil as a function of the duration of the cycle and occurrence of weeds. The autumn sowings resulted in a higher yield of floral capitula in both years. A linear reduction trend was also verified in the yield of floral capitula with the increase in plant spacing within the row from 0.05 to 0.20 m in the two crop years.  Uma camomila é uma opção socioeconômica importante para uma agricultura familiar. A cultura envolve os manuais de manejo e a restrição ao uso de herbicidas, o conhecimento sobre a interferência das plantas daninhas na produtividade de capítulos e a qualidade do óleo essencial ainda é limitado. Desta forma, objetivou-se estudar o efeito de datas de semeadura, espaçamentos entre plantas e manejo de capinas sobre a produtividade de capítulos, teor e produtividade de óleo essencial nas condições ambientais de uma região de clima subtropical úmido sem estação definida. Foram conduzidos experimentos nas datas (18/03, 28/04, 31/06 e 30/08/2017), com as plantas espaçadas em 0,05, 0,10, 0,15, 0,20, 0,30 e 0,40 m dentro das fileiras.Nas datas de 28/03 e 14/05/2018 os espaçamentos entre plantas na fileira foram de 0,05, 0,10, 0,15 e 0,20 m, incluindo-se dois manejos de capinas (com e sem plantas daninhas ) As variáveis ​​analisadas nos dois anos foram produtividade de capítulos florais secos, massa seca de plantas de camomila e plantas daninhas (gm - ²) e teor e produtividade de óleo essencial em 2018. Os dados de semeadura influenciam a produtividade de capítulos florais, teor e produtividade de óleo essencial em função da duração do ciclo e ocorrência de plantas daninhas. Semeaduras de outono resultaram em maior produtividade de capítulos florais nos dois anos.Também verificou-se tendência linear de redução na produtividade de capítulos florais com o aumento do espaçamento entre plantas na fileira de 0,05 para 0,20 m nos dois anos agrícolas. &nbsp

Phenology and productive performance of chamomile in sowing dates and spacing between plants

The present work has aimed to evaluate phenology and productive performance of chamomile in a subtropical weather region, sown in different dates and spacings in between plants. The experiment took place in Santa Maria – RS with four sowing dates in the year 2017 (18/03, 28/04, 30/06 and 31/08) and seven spacings along plants in rows (5, 10, 15, 20, 25, 30 and 40 cm), spaced 30 cm between each other. Phenological observations were made every two or three days in two plants per portion while also accounting for the number of nodes in the main stem. The harvest of chamomile floral chapters was performed manually from the beggining of flowering and repeated biweekly until plant maturation. Productivity of dry floral chapters as well as content and productivity of essential oils were evaluated. It was established that sowing dates affect the productivity of dry floral chapters, content and productivity of essential oil from cv. Mandirituba chamomile, with the sowings of March 18th and April 28th presenting the highest values for such variables. Increasing the space between plants from the 10 cm line to 40 cm in lines spaced in 30 cm has shown a linear tendency of decreasing the productivity of dry floral chapters. Spacings between plants did not affect the phenological development of chamomile, however, sowing dates interfered in the thermal time of six evaluated subperiods regarding plastochron and the final number of nodes.The present work has aimed to evaluate phenology and productive performance of chamomile in a subtropical weather region, sown in different dates and spacings in between plants. The experiment took place in Santa Maria – RS with four sowing dates in the year 2017 (18/03, 28/04, 30/06 and 31/08) and seven spacings along plants in rows (5, 10, 15, 20, 25, 30 and 40 cm), spaced 30 cm between each other. Phenological observations were made every two or three days in two plants per portion while also accounting for the number of nodes in the main stem. The harvest of chamomile floral chapters was performed manually from the beggining of flowering and repeated biweekly until plant maturation. Productivity of dry floral chapters as well as content and productivity of essential oils were evaluated. It was established that sowing dates affect the productivity of dry floral chapters, content and productivity of essential oil from cv. Mandirituba chamomile, with the sowings of March 18th and April 28th presenting the highest values for such variables. Increasing the space between plants from the 10 cm line to 40 cm in lines spaced in 30 cm has shown a linear tendency of decreasing the productivity of dry floral chapters. Spacings between plants did not affect the phenological development of chamomile, however, sowing dates interfered in the thermal time of six evaluated subperiods regarding plastochron and the final number of nodes

Soil water and wheat, soybean, and maize yields associated to El Niño Southern Oscilation

O objetivo deste trabalho foi simular o conteúdo de água disponível no solo e o rendimento das culturas de trigo, soja e milho, em Santa Maria, RS, e associá-los ao fenômeno El Niño Oscilação Sul (ENOS). O período estudado foi de 1969 a 2003. A água disponível no solo e o rendimento das culturas foram calculados com modelos matemáticos disponíveis na literatura. A água disponível no solo foi representada pela fração de água transpirável no solo pelas plantas. Foi constatado que a menor disponibilidade hídrica no solo está associada a anos neutros, e a maior disponibilidade hídrica está relacionada a eventos do El Niño. Os anos de La Niña foram os mais favoráveis ao rendimento de grãos da cultura de trigo, enquanto os anos de El Niño foram os mais favoráveis ao rendimento de grãos de soja e milho. Ficou evidente que os anos classificados como neutros, em relação ao ENOS, são os de maior risco de perda de rendimento de grãos destas duas culturas de verão, em conseqüência da menor disponibilidade hídrica no solo, o que é uma informação importante no planejamento de estratégias para o agronegócio relativamente a uma previsão do fenômeno ENOS.The objective of this study was to simulate soil water content, and wheat, soybean and maize yields, in Santa Maria, RS, Brazil, and link their interannual variability to El Niño Southern Oscillation (ENSO). The period studied was 1969 to 2003. Soil water content and the yields of wheat, soybean and maize were simulated with models available in the literature. Soil water content was represented by the fraction of transpirable soil water. The results showed that the lowest soil water content in Santa Maria is associated to neutral years and the highest soil water is associated to El Niño events. La Niña years were more favorable to high wheat yield, whereas El Niño years were more favorable to high soybean and maize yields. It was evident that years classified as neutral years in respect to ENSO are riskier to grain yields of soybean and maize crops, which is an important information for planning strategies in agribusiness considering ENSO forecast

Linking rainfall variability in Santa Maria with the Pacific Decadal Oscillation

O objetivo deste trabalho foi verificar a associação da variabilidade interdecadal da chuva em Santa Maria, RS, com a Oscilação Decadal do Pacífico. Parte da variabilidade interanual da precipitação pluvial é explicada pelo fenômeno El Niño Oscilação Sul (ENOS), que acontece no Oceano Pacífico. Na segunda metade da década de 1990, foi relatada outra oscilação na temperatura do Oceano Pacífico, de duração maior que o ENOS, denominada Oscilação Decadal do Pacífico (ODP). Foram usados os dados mensais acumulados de precipitação do período 1912–2008, da Estação Climatológica principal de Santa Maria, e os valores mensais do índice ODP do mesmo período. A análise foi realizada em nível anual, semestral (primeiro e segundo semestre), sazonal (verão, outono, inverno e primavera) e mensal. Existe associação entre a chuva e a ODP, de modo que décadas com chuvas acima da normal são associadas à fase quente da ODP, intercaladas com décadas com chuva abaixo da normal associadas à fase fria da ODP, o que indica oscilações periódicas de médio e longo prazo na precipitação pluvial em Santa Maria, RS.The objective of this work was to verify the association of the interdecadal variability of rainfall in Santa Maria, Rio Grande do Sul state, Brazil, with the Pacific Decadal Oscillation. Part of the interannual variation in rainfall is explained by the El Niño Southern Oscillation (ENSO) in the Pacific Ocean. In the second half of the 1990s, another oscillation in the surface temperature of the Pacific Ocean was reported, with greater duration than ENSO, named the Pacific Decadal Oscillation (PDO). Monthly precipitation data collected at the Meteorological Station of Santa Maria of the 1912–2008 period and monthly PDO indices of the same period were used. The analyses were performed on an annual, semestral (first and second semester), seasonal (Summer, Fall, Winter, and Spring), and monthly basis. There is a link between rainfall and PDO, because decades with precipitation higher than normal are associated with a warm phase of PDO, followed by decades with below-normal rainfall associated with a cool phase of PDO, which indicate mid and long-term periodic oscillations of rainfall in Santa Maria

Water excess in different soils and sowing times for sunflower in the state of Rio Grande do Sul, Brazil

O objetivo deste trabalho foi identificar datas de semeadura com menor ocorrência média de dias com excedente hídrico para a cultura do girassol, e determinar a persistência de dias consecutivos com excedente hídrico ao se considerar a capacidade de armazenamento de água disponível de diferentes solos da região central do Rio Grande do Sul. O desenvolvimento da cultura e o aprofundamento do sistema radicular foram simulados de acordo com a soma térmica para 14 datas de semeadura, de agosto até meados de fevereiro, com dados de 1968 até 2011. A partir da capacidade de armazenamento de água disponível para as diferentes classes de solos da região, calculou-se o balanço hídrico sequencial diário para determinar os dias com excesso hídrico. Avaliou-se a ocorrência de dias com excesso hídrico em diferentes subperíodos de desenvolvimento da cultura, e procedeu-se à análise exploratória com gráficos box‑plot para determinação da persistência de dias consecutivos com excesso hídrico durante todo o ciclo da cultura. O excedente hídrico limita o cultivo de girassol em determinadas áreas e períodos na região central do Rio Grande do Sul. A persistência de dias consecutivos com excedente hídrico e a duração do ciclo de desenvolvimento da cultura são  influenciados pela data de semeadura.The objective of this work was to identify sowing dates with the lowest average occurrence of days with water excess for sunflower crop, and to determine the persistence of consecutive days with water excess considering the available water storage capacity of different soils of the central region of the state of Rio Grande do Sul, Brazil. Crop development and root system deepening were simulated based on thermal summation for 14 sowing dates, from August until mid‑February, with data from 1968 to 2011. From the available water storage capacity of the different soil classes of the region, the sequential daily water balance was calculated to determine the days with water excess. The occurrence of days with water excess was evaluated in different crop development sub‑periods, and exploratory analysis with box‑plot graphs was performed to determine the persistence of consecutive days with water excess during the crop cycle. Water excess limits sunflower cultivation in some areas and periods in the central region of the state of Rio Grande do Sul. The persistence of consecutive days with water excess and the duration of the crop development cycle are influenced by the sowing date

Modeling wheat development considering different cardinal temperatures and methods for the temperature response function calculation

O objetivo deste trabalho foi melhorar a estimativa dos estádios de desenvolvimento de genótipos brasileiros de trigo (Triticum aestivum) realizada por meio do modelo WE-Streck. Foram avaliadas diferentes combinações de temperaturas cardinais e métodos de cálculo da função de resposta à temperatura. Dados referentes às datas da emergência, da emissão da espigueta terminal, da antese e da maturidade fisiológica de seis genótipos brasileiros de trigo semeados em 11 datas ao longo de três anos (2005, 2006 e 2007) em Santa Maria, RS, foram usados para estimar os coeficientes do modelo WE-Streck modificado e testar as diferentes combinações de temperaturas cardinais e métodos de cálculo da função de resposta à temperatura. Para os genótipos BRS Louro, BRS 177, CEP 51, CEP 52 e Nova Era, a simulação do desenvolvimento com o modelo de WE-Streck é melhor quando são usados maiores valores de temperaturas cardinais ótima e máxima, em comparação às usadas originalmente no modelo. Para o genótipo BRS Tarumã, devem ser utilizadas as temperaturas cardinais do modelo WE-Streck original. É recomendável usar as temperaturas mínimas e máximas diárias para calcular a função de resposta à temperatura quando o modelo WE-Streck for usado para simulação do desenvolvimento de genótipos brasileiros de trigo.The objective of this work was to improve the prediction of developmental stages of Brazilian wheat (Triticum aestivum) genotypes made using the WE-Streck model. Different combinations of cardinal temperatures and methods of calculating the temperature response function were evaluated. Data regarding the dates of emergence, terminal spikelet, anthesis, and physiological maturity of six Brazilian wheat genotypes sown on 11 dates during three years (2005, 2006, and 2007) at Santa Maria, RS, Brazil, were used to estimate the WE-Streck model coefficients and to evaluate the different combinations of cardinal temperatures and methods for calculating the temperature response function. For the genotypes BRS Louro, BRS 177, CEP 51, CEP 52, and Nova Era, the simulation of the development with the WE-Streck model is better with higher values of optimum and maximum cardinal temperatures compared to those originally used in the model. For the genotype BRS Tarumã, the cardinal temperatures from the original version of the WE-Streck model should be used. It is recommended that the minimum and maximum daily temperatures be used to calculate the temperature response function when the WE-Streck model is selected for simulating the development of Brazilian wheat genotypes

Modification of canola cultivation conditions in a waterlogging-susceptible subtropical environment

Waterlogging directly interferes with the production capacity of agricultural crops in response to the morphophysiological changes caused to plants. Since the cultivation of poorly drained soils is traditionally avoided, this study aimed to evaluate the possibility of expanding canola cultivation into waterlogged soils using soil surface drainage and different row spacings in lowland areas of Rio Grande do Sul, Brazil. Treatments consisted of the presence and absence of surface drains at 0.25 m depth and row spacings of 0.17, 0.34, 0.51, and 0.68 m arranged in two-factorial randomized blocks with four replications, in 2018 and 2019. In this study, growth traits, yield components, and the final grain yield of canola were evaluated. The increase in lateral branching in canola plants was found to be directly related to waterlogging and negatively affected yield. The use of drains positively impacted the number of pods per plant, seeds per pod, the 1,000 seeds weight, and grain yield. The more intense waterlogging conditions in 2018 resulted in the highest grain yield and superior production traits were obtained with row spacings between 0.41 and 0.48 m. In the absence of waterlogging, the 0.17 m row spacing was more productive. Canola cultivation can occur in waterlogged soils in the presence of surface drainage and at row spacings ranging from 0.40 to 0.50 m