Climatic effects on sugarcane ripening under the influence of cultivars and crop age

The lack of information about the effects of cultivars, crop age and climate on the sugarcane (Saccharum ssp.) crop yield and quality has been the primary factor impacting the sugar-ethanol sector in Brazil. One of the processes about which we do not have a satisfactory understanding is sugarcane ripening and the effects of cultivars, crop age and climate on that. Sugarcane ripening is the process of sucrose accumulation in stalks, which is heavily influenced by several factors, mainly by climatic conditions such as air temperature and water deficits. Because it is a complex process, studies of the variables involved in sugarcane ripening can provide important information, resulting in a better use of commercial cultivars, bringing advantages to growers, processing units, breeding programs and scientific community. In this review, we discuss the available knowledge of the interaction between climate conditions and sugarcane ripening, under the influence of genotypic characteristics and crop age. In several studies, the main conclusion is that sugarcane ripening depends on a complex combination of climate variables, the genetic potential of cultivars and crop management. Soil moisture and air temperature are the primary variables involved in sugarcane ripening, and their combination stimulates the intensity of the process. In addition, the need for studies integrating the effects of climate on plant physiological processes and on the use of chemical agents to stimulate sugarcane ripening is highlighted

Modeling sugarcane ripening as a function of meteorological variables

O efeito das variáveis meteorológicas na maturação da cana-de-açúcar é um processo ainda pouco conhecido, apesar de apresentar inúmeros impactos à qualidade da matéria-prima para a indústria sucro-energética brasileira. O objetivo do presente trabalho foi avaliar os efeitos das variáveis meteorológicas no processo de maturação de cultivares de cana-de-açúcar e gerar modelos capazes de descrevê-lo. O experimento foi realizado em área pertencente ao Grupo Raízen (ex-Cosan), em Piracicaba, SP, no período de março de 2002 a outubro de 2003. Foram avaliadas oito cultivares de cana-de-açúcar em 32 amostragens realizadas de março a outubro de 2003. Variáveis relacionadas à qualidade de matéria-prima da cana-de-açúcar (ATR, AR, ART, Pureza, Brix, Pol%cana, fibra e umidade) e variáveis meteorológicas (temperatura do ar, precipitação, radiação solar, entre outras) foram submetidas à análise estatística descritiva e multivariada, visando melhorar a compreensão do processo de maturação e suas relações com as condições ambientais. As variáveis meteorológicas de melhor correlação com as variáveis de qualidade da cana-de-açúcar foram utilizadas na elaboração de modelos descritivos do processo de maturação, os quais foram agrupados em precoces, médios e tardios, de acordo com o padrão de maturação das cultivares estudadas. A avaliação dos modelos foi realizada pela análise dos resíduos (presença de outliers, homogeneidade das variâncias e normalidade dos resíduos) e pela comparação com dados independentes (erros médios, R2, índice de concordância de Willmott e índice de confiança de Camargo). Independente do padrão de maturação (precoce, médias e tardias), os modelos de melhor desempenho foram aqueles que descreveram as variáveis ATR, Brix, Pol%cana e umidade, com valores de R2 ajustado acima de 0,9 (p significativo a 1%) e ótimo desempenho segundo índice C de Camargo (acima de 0,85), quando testados com dados independentes. O modelo de fibra apresentou os menores valores de R2 ajustado (em torno de 0,65) e não normalidade dos resíduos. Contudo, sua avaliação com dados independentes levou à obtenção de valores de índice C acima de 0,8. Os modelos gerados mostram que a precipitação pode ser utilizada como a principal variável na previsão da qualidade da matéria-prima da cana-de-açúcar e que seu uso pode ser estendido a outras áreas além daquela para onde foi inicialmente gerado.The effect of meteorological variables on sugarcane ripening is a not very well known process in spite of the several impacts of that on the quality of the raw material for the sugarcane industry. The objective of this study was to evaluate the effects of meteorological variables on sugarcane ripening and based on that to establish models able to describe this process. The study was conducted in an area of the Raízen Group (former Cosan), in Piracicaba, state of São Paulo, Brazil, from March 2002 (planting) to October 2003. Eight sugarcane cultivars were evaluated by analyzing 32 samples collected from March to October 2003. Variables related to the quality of the raw material (ATR, AR, ART, Purity, Brix, Pol%cane, fiber and moisture) and weather (air temperature, rainfall, solar radiation, among others) were submitted to descriptive and multivariate statistical analysis in order to better understand the sugarcane ripening process and the relationship between this process and environmental conditions. The meteorological variables of best fit were used for elaborating the models to describe the ripening process, which were grouped into early, middle and late, according to the maturity pattern of the studied cultivars. The evaluation of the models was based on the analysis of residuals (presence of outliers, homogeneity of variances and normality of residuals) and on the comparison between estimated and independent data (mean errors, R2, agreement index of Willmott and confidence index of Camargo). Regardless of the pattern of sugarcane maturation (early, middle and late), the models that presented the best performance were for ATR, Brix, Pol% cane and humidity variables, with adjusted R2 values above 0.9 (p significant at 1%) and excellent performance, with C index above 0.85, when evaluated with independent data. The fiber model had the lowest adjusted R2 values (around 0.65) and problems in the distribution of its residuals (non-normality); however, when it was tested with independent data an acceptable performance was found, with C index above 0.8. The generated models showed that precipitation can be used as the main variable for predicting sugarcane quality and that its use can be extended to other areas than the one where it was originally generated

Climatic effects on sugarcane ripening under the influence of cultivars and crop age

The lack of information about the effects of cultivars, crop age and climate on the sugarcane (Saccharum ssp.) crop yield and quality has been the primary factor impacting the sugar-ethanol sector in Brazil. One of the processes about which we do not have a satisfactory understanding is sugarcane ripening and the effects of cultivars, crop age and climate on that. Sugarcane ripening is the process of sucrose accumulation in stalks, which is heavily influenced by several factors, mainly by climatic conditions such as air temperature and water deficits. Because it is a complex process, studies of the variables involved in sugarcane ripening can provide important information, resulting in a better use of commercial cultivars, bringing advantages to growers, processing units, breeding programs and scientific community. In this review, we discuss the available knowledge of the interaction between climate conditions and sugarcane ripening, under the influence of genotypic characteristics and crop age. In several studies, the main conclusion is that sugarcane ripening depends on a complex combination of climate variables, the genetic potential of cultivars and crop management. Soil moisture and air temperature are the primary variables involved in sugarcane ripening, and their combination stimulates the intensity of the process. In addition, the need for studies integrating the effects of climate on plant physiological processes and on the use of chemical agents to stimulate sugarcane ripening is highlighted

Climatic effects on sugarcane ripening under the influence of cultivars and crop age

The lack of information about the effects of cultivars, crop age and climate on the sugarcane (Saccharum ssp.) crop yield and quality has been the primary factor impacting the sugar-ethanol sector in Brazil. One of the processes about which we do not have a satisfactory understanding is sugarcane ripening and the effects of cultivars, crop age and climate on that. Sugarcane ripening is the process of sucrose accumulation in stalks, which is heavily influenced by several factors, mainly by climatic conditions such as air temperature and water deficits. Because it is a complex process, studies of the variables involved in sugarcane ripening can provide important information, resulting in a better use of commercial cultivars, bringing advantages to growers, processing units, breeding programs and scientific community. In this review, we discuss the available knowledge of the interaction between climate conditions and sugarcane ripening, under the influence of genotypic characteristics and crop age. In several studies, the main conclusion is that sugarcane ripening depends on a complex combination of climate variables, the genetic potential of cultivars and crop management. Soil moisture and air temperature are the primary variables involved in sugarcane ripening, and their combination stimulates the intensity of the process. In addition, the need for studies integrating the effects of climate on plant physiological processes and on the use of chemical agents to stimulate sugarcane ripening is highlighted

Modelagem da área foliar de duas cultivares de amendoim em função das dimensões lineares dos folíolos

The purpose of this study was to determine a shape factor to estimate area of leaflets of two peanut cultivars (IAC TATU ST, IAC RUNNER 886). Correlation studies were conducted involving real leaf area (Sf) and leaf length (C), maximum leaf width (L) and the product between C and L. For each cultivar was determined a form factor (f) by means of regression analysis between the product of the length by the width and the actual area of leaves and the correlation between leaf area estimated by the correction factor and direct measurement. All evaluated models (linear, exponential or geometric) provided good estimates of leaf area (above 87%). Linear models had the best fit, passing or not through the origin. From a practical viewpoint, it is suggested to use the linear model involving the C and L product, using a linear coefficient equal to zero, with values of factor f equal to 0.7111 and 0.7266 for IAC RUNNER 886 and IAC TATU ST, respectively. The method of dimensions is feasible for the estimation of leaf area for both peanut cultivars, for showing good r(2) values (0.97), with errors below 3%, even when used with independent data.O objetivo do presente estudo foi determinar um fator de forma para a estimativa da área de folíolos de dois cultivares de amendoim (IAC TATU ST e IAC RUNNER 886). Foram estudadas as correlações entre a área foliar real (SF) e as medidas dimensionais do limbo foliar, como o comprimento ao longo da nervura principal (C), a largura máxima (L) e o produto das duas dimensões (C  L). Para cada cultivar foi determinado um fator de forma (f) por meio da análise de regressão entre o produto do comprimento e largura e área real das folhas e avaliada a correlação entre a área foliar estimada pelo fator de correção e sua medida direta. Todos os modelos avaliados (lineares, exponenciais ou geométricos) permitiram estimativas da área foliar acima de 87%. As equações que apresentaram melhor ajuste foram as lineares, passando ou não pela origem. Do ponto de vista prático, sugere-se optar pela equação linear simples que considera o coeficiente linear igual a zero, com valores de fator f iguais a 0,7111 e 0,7266 para os cultivares IAC RUNNER 886 e IAC TATU ST, respectivamente. O método das dimensões é viável para a estimação de área foliar do amendoim para ambas as cultivares, por apresentar valores de r2 (0,97), com erros inferiores a 3%, inclusive quando utilizado com dados independentes

Germinação de sementes de melão-de-são-caetano sob variação de água, luz e temperatura

The purpose of this study was to evaluate germination of Momordica charantia L. seeds under different conditions of: water availability (0.0, -0.2, -0.4, -0.6, -0.8 and -1.0 MPa), temperature (10, 15, 20, 25, 30 and 35 degrees C) and quality of incident light (filter dark, red, green, yellow, red off, blue, orange and without filter). For each variable evaluated, experiments were carried out in a completely randomized design with four replicates kept under controlled conditions (germination chamber). There were higher percentages of germination under conditions of mild water restriction (-0.2 MPa) and temperatures around 25 degrees C, regardless of the quality of light. Temperatures below 20 degrees C and above 30 degrees C reduced germination, although lower temperatures had strongly effects on germination. Water availability lower than -0.2 MPa strongly reduced germination, which was inhibited in the treatments of -0.8 and 1.0 MPa.Objetivou-se estudar respostas germinativas das sementes de melão-de-São Caetano (Momordica charantia L.) em diferentes condições de: disponibilidade de água (0,0, -0,2, -0,4, -0,6, -0,8 e -1,0 MPa), temperatura (10, 15, 20, 25, 30 e 35 °C) e qualidade de luz incidente (filtro escuro, vermelho, verde, amarelo, vermelho distante, azul, laranja e sem filtro). Para cada variável avaliada, realizou-se um experimento, em delineamento inteiramente casualizado com quatro repetições, os quais eram mantidos em condições controladas (câmara de germinação). As sementes de melão-de-São Caetano apresentaram maiores percentagens de germinação em condições de leve restrição hídrica (-0,2 MPa) e temperaturas em torno de 25 oC, independente da qualidade da luz. Temperaturas abaixo de 20 oC e acima de 30 oC reduziram a germinação, embora temperaturas mais baixas tenham reduzindo mais intensamente a germinação. Os potenciais osmóticos menores que -0,2 MPa reduziram fortemente a germinação, a qual foi inibida nos tratamentos de -0,8 e 1,0 MPa

OVERCOMING DORMANCY SEEDS AND CHEMICAL CONTROL OF \ud Momordicacharantia L.

Objetivou-se com este estudo avaliar diferentes métodos para a superação da dormência das sementes e a eficiência de herbicidas no controle químico de plantas de Momordicacharantia L. no estádio reprodutivo. O primeiro experimento constituiu-seem esquema fatorial 2 x 8 (duas épocas de coleta das sementes (2006 e 2007) e oito \ud métodos de quebra de dormência: escarificação mecânica; imersão em ácido sulfúrico concentrado e a 50%; imersão em nitrato de potássio a 2%por três e seis horas; calor seco a 60°C; água quente a 60°C e uma testemunha sem tratamento). No segundo ensaio avaliou-se o controle da Momordicacharantia L. por meio de seis herbicidas distintos: Imazapic, Metsulfuron-methyl, Metribuzin, 2,4-D, Amicarbazone, Paraquat e uma testemunha sem aplicação de herbicidas. Em ambos os ensaios, o delineamento experimental utilizado foi o inteiramente casualizados, com quatro repetições. Após a aplicação dos tratamentos,pode-se concluir que a imersão das sementes em ácido sulfúrico concentrado por 3 minutos \ud proporcionou uma maior porcentagem e velocidade de germinação e que o herbicida Metribuzin alcançou, embora tardiamente, um controle total das plantas de melão de São-Caetano.This experiment were performed to evaluate methods of seeds scarification for overcoming dormancy and the efficacy of six herbicides registered for sugarcane to control adult plants of Mcharantia. The experimental design was completely randomized, with four replications in both trials. The first trial is a factorial 2x8 (two times of seeds collection (2006 and 2007) with eight methods of breaking dormancy (mechanical scarification; 100% and 50% concentrated sulfuric acid; 2% potassium nitrate for three and six hours; heat dried at 60 degrees C; hot water at 60 degrees C and an untreated control). In the second trial evaluated the control of M. charantia through six different herbicides: Imazapic, Metsulfuron-methyl, Metribuzin, 2,4-D, Amicarbazone, Paraquat and a control without herbicide application. Thus, it can be concluded that the seeds were immersed in concentrated sulfuric acid for three minutes and potassium nitrate for three hours gave a higher percentage and germination speed and the herbicide Metribuzin reached, albeit belatedly, a total control of M. charantia