Variabilidade espacial do banco de sementes de plantas daninhas em área de cana-de-açúcar
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Data
2021-10-18
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Universidade Estadual Paulista (Unesp)
Resumo
O levantamento fitossociológico adicionada com as técnicas geoestatísticas e análise de redes podem contribuir para monitoramento do banco de sementes revelando o padrão de dispersão das sementes de plantas daninhas em cultivos de cana-de-açúcar e influenciando a tomada de decisão. Logo, a hipótese é que a distribuição e/ou dispersão de sementes das plantas daninhas poderá apresentar variabilidade espacial por estar influenciada por fatores externos mediante ao manejo do solo decorrente da mecanização agrícola no período de reforma do canavial, do relevo por sua declividade e pelo escoamento superficial da área. O objetivo do trabalho foi caracterizar a variabilidade espacial da distribuição do banco de sementes de plantas daninhas em duas áreas respectivamente, encosta superior e meia encosta, por meio do levantamento fitossociológico onde avaliaram-se os parâmetros dos índices de similaridade, frequência e densidade das sementes de plantas daninhas em área de cultivo de cana-de-açúcar. O experimento foi conduzido na cidade de Guariba, São Paulo, na Usina São Martinho, o solo é classificado como latossolo vermelho eutroférrico, com produção ativa de mais de 30 anos apresentando em sua paisagem um leve declive. Para caracterização da variabilidade espacial realizou-se a análise geoestatística mediante a demarcação de 55 pontos em cada parte da área total de estudo que foi dividida em duas, a área da encosta superior e a área da meia encosta. Em cada ponto foram extraídas dez subamostras totalizando 550 subamostras por área. Com os dados obtidos empregaram-se as análises geoestatísticas tendo a representação do variograma na descrição gráfica da relação entre as distâncias e entre as áreas observadas em estudo e a média desses valores entre as áreas na visualização da espacialização do banco de sementes. Os resultados demonstraram haver dependência espacial na distribuição do banco de sementes para comunidade que apresentou o alcance máximo com valores de 28,29 m, na encosta superior e 13,53 m, na meia encosta, e que dentro desse limite apresentam distribuição contínua na formação do banco de sementes de plantas daninhas, portanto, após esses limites indicam que os valores são independentes entre si, não havendo autocorrelação. Os mapas de padrão espaciais acusam através do levantamento fitossociológico e da análise geoestatística o comportamento de distribuição das sementes ao longo das áreas. O uso da representação esquemática com a análise de grafos e redes, mediante as análises geoestatísticas dos pontos amostrados, possibilitou por meio de densidade, conectividade e proximidade dos pontos observar o comportamento da distribuição de sementes nas áreas em estudo, encosta superior e meia encosta, revelando que o banco de sementes está em conformidade com o fluxo de escoamento superficial do solo. O emprego das técnicas de geoestatística, o estudo fitossociológico e a análise de redes se complementam e direcionam para identificar as comunidades infestantes e o padrão de distribuição ao longo da área de cana-de-açúcar.
The phytosociological survey added with geostatistical techniques and network analysis can contribute to monitoring the seed bank, revealing the pattern of weed seed dispersion in sugarcane crops and influencing decision-making. Therefore, the hypothesis is that the distribution and/or dispersion of weed seeds present spatial variability as it is influenced by external factors through soil management resulting from agricultural mechanization in the period of sugarcane reform, the relief by its slope and by the área runnof. The objective of this work was to characterize the spatial variability of the distribution of weed seeds in two areas, respectively, upper slope and half slope, through a phytosociological survey where the parameters of similarity, frequency and seed density indices were evaluated of weeds in sugarcane cultivation area. The experiment was conducted in the city of Guariba, São Paulo, at Usina São Martinho, the soil is classified as eutroferric red latosol, with active production for more than 30 years, presenting a slight slope in its landscape. To characterize the spatial variability, a geostatistical analysis was performed by demarcating 55 points in each part of the total study area, which was divided into two, the upper slope area and the half slope area. At each point, ten sub-samples were extracted, totaling 550 sub-samples per area. With the data obtained, geostatistical analyzes were used with the representation of the variogram in the graphic description of the relationship between the distances the áreas observed under study and the average of these values between the áreas in the visualization of spatialization of the seed bank. The results showed that there is spatial dependence in the distribution of the seed bank for the community that presented the maximum reach with values of 28.29 m, on the upper slope and 13.53 m, on the middle slope, and that within this limit they presente continuous distribution in the formation from the weed seed bank, therefore, after these limits indicate that the values are independent from each other with no autocorrelation. The spatial pattern maps show, through the phytosociological survey and the geostatistical analysis, the seed distribution behavior along the areas. The use of schematic representation with the analysis of graphs and networks, through geostatistical analyzes of the sampled points, made it possible, through density, connectivity and proximity of the points, to observe the behavior of seed distribution in the areas under study, upper slope and half slope, revealing that the seed bank is in compliance with the soil surface flow. The use of geostatistical techniques, the phytosociological study and the analysis of networks complement each other and guide each other to identify weed communities and the distribution pattern along the sugarcane area.
The phytosociological survey added with geostatistical techniques and network analysis can contribute to monitoring the seed bank, revealing the pattern of weed seed dispersion in sugarcane crops and influencing decision-making. Therefore, the hypothesis is that the distribution and/or dispersion of weed seeds present spatial variability as it is influenced by external factors through soil management resulting from agricultural mechanization in the period of sugarcane reform, the relief by its slope and by the área runnof. The objective of this work was to characterize the spatial variability of the distribution of weed seeds in two areas, respectively, upper slope and half slope, through a phytosociological survey where the parameters of similarity, frequency and seed density indices were evaluated of weeds in sugarcane cultivation area. The experiment was conducted in the city of Guariba, São Paulo, at Usina São Martinho, the soil is classified as eutroferric red latosol, with active production for more than 30 years, presenting a slight slope in its landscape. To characterize the spatial variability, a geostatistical analysis was performed by demarcating 55 points in each part of the total study area, which was divided into two, the upper slope area and the half slope area. At each point, ten sub-samples were extracted, totaling 550 sub-samples per area. With the data obtained, geostatistical analyzes were used with the representation of the variogram in the graphic description of the relationship between the distances the áreas observed under study and the average of these values between the áreas in the visualization of spatialization of the seed bank. The results showed that there is spatial dependence in the distribution of the seed bank for the community that presented the maximum reach with values of 28.29 m, on the upper slope and 13.53 m, on the middle slope, and that within this limit they presente continuous distribution in the formation from the weed seed bank, therefore, after these limits indicate that the values are independent from each other with no autocorrelation. The spatial pattern maps show, through the phytosociological survey and the geostatistical analysis, the seed distribution behavior along the areas. The use of schematic representation with the analysis of graphs and networks, through geostatistical analyzes of the sampled points, made it possible, through density, connectivity and proximity of the points, to observe the behavior of seed distribution in the areas under study, upper slope and half slope, revealing that the seed bank is in compliance with the soil surface flow. The use of geostatistical techniques, the phytosociological study and the analysis of networks complement each other and guide each other to identify weed communities and the distribution pattern along the sugarcane area.
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Palavras-chave
Ervas daninhas, Análise espacial, Grafos de ligação, Weeds, Spatial analysis, Connection graphs