Abstract The development of crops is related to their nutritional status and the leaf chlorophyll apparent index. The objective of this study was to use fuzzy classification to determine the degree of membership (fuzzy index - FI) of macronutrientes and leaf micronutrients classified as low, adequate and high, quantify the chlorophyll index and to determine the spatial variability of these attributes for the rubber tree (Hevea brasiliensis) (Fx 3864) at the initial stage of development, aiming at the definition of management zones. Sampling grid regulates at 6x7 m spacing was built to determine the attributes: chlorophyll a and b, macro and leaf micronutrients, totaling 100 sample points. The fuzzy classification and geostatistical was used to map the nutritional status of the rubber tree. In the fuzzy analysis the macronutrient map shows the degree of membership 0.50<FI<0.75, in more than 75% of the area, indicating high nutritional status. The limiting factor was the concentration of P in the lowest percentage of points (58%) in the appropriate class. Micronutrients have 0.25<FI<0.50, for more than 75% of the area, therefore, average nutritional status. Leaf Cu presented 48% of the data in low sufficiency. Therefore, it is recommended to analyze macronutrients and leaf micronutrients separately to define management zones for foliar fertilization. Chlorophyll a, b and a/b leaf index do not correlate with macronutrients and fuzzyficated micronutrients. The leaf indices of chlorophyll a and b have a very high correlation (r = 0.89).

Abstract The aim of this study was to evaluate spatial behavior and temporal stability of rainfall and mean air temperature in the state of Bahia, using historical series from 1975 to 2011 and 1961 to 2009, respectively. The analyses were performed considering the accumulated variables of each month of the historical series. The accumulated monthly totals were divided by the number of years of observation, obtaining the monthly average values of rainfall and air temperature for each measurement point. The data were submitted to descriptive statistical analysis and linear correlation studies. Geostatistical analysis was used to verify the existence and quantify spatial dependence between the values of the studied variables. In addition, the maps were submitted to algebra operations, calculating the spatial difference between months for each of the variables. For that purpose, the difference between one month and its subsequent period was calculated in order to establish the behavior of the variables over time. Climatic variables showed a close relationship between each other, demonstrating their spatial and temporal variation, which is mainly dependent on the seasons of the year. The rainfall and mean air temperature variables showed stable spatial behavior and high temporal stability between subsequent months.

Abstract This study evaluated the eradication of eucalyptus sprouts after chemical weeding using a diagrammatic scale over time. The research was conducted in fields planted with eucalyptus in forest reform areas, in Itabela, Bahia, Brazil, during the pre-planting herbicide application. The application was carried out in five fields, which were considered as sample units of the different treatments. The effectiveness of chemical weeding for controlling sprout growth was evaluated in fifty plants per treatment, randomly selected in three periods after application. The plants were evaluated visually using a diagrammatic scale to assign scores between 1 and 5 to the sprout control percentage. After the visual evaluations, the frequency distribution of the sprouting percentage for each score was calculated. Subsequently, the scores were submitted to a clustering analysis by the Ward method, to evaluate the relationship between different fields and periods for each treatment in homogeneous clusters. The results showed that treatments only controlled the sprouts in the short term, without providing effective eradication. The diagrammatic scoring scale allowed evaluating the vegetative vigor of the eucalyptus sprouts, generating interpretable information on the different evaluated treatments, making it a useful tool for managing silvicultural treatments and evaluating the application efficacy of phytosanitary products.

RESUMO Objetivou-se neste estudo avaliar a variabilidade espaço-temporal do índice foliar de clorofila e a relação com a produtividade do cacaueiro. O experimento foi realizado em uma área experimental de produção de cacau localizada no município de Ilhéus, BA. O índice foliar de clorofila foi medido nos meses de setembro, outubro, janeiro, fevereiro, março e abril na safra 2014/2015 em cada ponto amostral de uma malha regular, utilizando-se um medidor portátil de clorofila. Nas mesmas condições, a produtividade foi avaliada e os dados foram submetidos à estatística descritiva e estudo de correlação linear. A análise geoestatística foi utilizada para determinar e quantificar a variabilidade espacial e temporal do índice foliar de clorofila e da produtividade. O índice foliar de clorofila variou ao longo do período avaliado, porém os meses de fevereiro, março e abril não apresentaram dependência espacial na área em estudo, indicando ausência de estabilidade temporal. A produtividade mensal do cacaueiro, exceto no mês de janeiro, apresentou elevada variabilidade espacial. Nas condições estudadas, não foi possível estabelecer uma relação entre o índice foliar de clorofila e a produtividade do cacaueiro.

ABSTRACT The objective of this study was to evaluate the spatial-temporal variability of leaf chlorophyll index and its relationship with cocoa yield. The experiment was carried out in an experimental area of cocoa production located in Ilhéus, Bahia State, Brazil. Leaf chlorophyll content was measured in September, October, January, February, March and April in the 2014/2015 season, at each sampling point of a regular grid by using a portable chlorophyll meter. Under the same conditions, yield was evaluated and the data were submitted to descriptive statistics and a linear correlation study. Geostatistical analysis was used to determine and quantify the spatial and temporal variability of leaf chlorophyll index and yield. Leaf chlorophyll index varied over the period evaluated, but the months of February, March and April showed no spatial dependence in the study area, indicating absence of temporal stability. Cocoa monthly yield, except in January, presented high spatial variability. Under the conditions of this study, it was not possible to establish a relationship between leaf chlorophyll index and cocoa yield.