地块尺寸,样本充足,重复次数是影响实验误差或残差以及处理间真实差异表达的因素。这项研究的目的是确定,使用统计模型,通过评估农药地面施用中的叶面喷雾沉积和土壤径流,为咖啡作物的施用技术实验提供合适的样本量。在第一阶段,我们确定了每套叶子的数量以及用于洗涤叶子和提取示踪剂的溶液的体积。我们分析了两种液滴类别(细和粗)中提取的示踪剂量的变异系数(CV)之间的变异性,对于植物的不同部分,以及每组不同数量的叶子,分为五个叶子的间隔(1-5、6-10、11-15和16-20)。在每组10片叶子并使用100mL提取溶液的间隔中发现的变异性较小。在第二阶段,使用20个地块的完全随机设计进行了田间试验:10个喷有细液滴,10个喷有粗液滴。在每个情节中,从咖啡树的上部和下部冠层收集10组(样品),每组10片叶子。此外,每个地块放置10个培养皿并在施用后收集。根据喷雾沉积的结果(每cm2叶片提取的示踪剂质量),我们使用最大曲率和最大曲率的变异系数方法确定了最佳样本量。更高的变异性与更难以达到的目标有关。因此,这项研究确定了喷雾沉积的五到八组叶子之间的最佳样本量,和四到五个土壤径流培养皿。
Plot size, sample sufficiency, and number of repetitions are factors that affect the experimental errors or residuals and the expression of true differences among treatments. The objective of this study was to determine, using statistical models, the appropriate sample size for application technology experiments in coffee crops through the evaluation of foliar spray deposition and soil runoff in the ground-based application of pesticides. In the first stage, we determined the quantity of leaves per set and the volume of the solution for washing the leaves and extracting the tracer. We analyzed the variability between the coefficients of variation (CVs) of the amount of tracer extracted in two droplet classes (fine and coarse), for the different parts of the plants, and for the different quantities of leaves per set that were organized into intervals of five leaves (1-5, 6-10, 11-15, and 16-20). Less variability was found in the intervals with 10 leaves per set and using 100 mL of extraction solution. In the second stage, a field experiment was conducted using an entirely randomized design with 20 plots: 10 sprayed with fine droplets and 10 with coarse droplets. In each plot, 10 sets (samples) with 10 leaves each were collected from the upper and lower canopy of the coffee trees. Moreover, 10 Petri dishes were placed per plot and collected after application. Based on the results of the spray deposition (mass of tracer extracted per cm2 of leaf), we determined the optimal sample size using the maximum curvature and maximum curvature of the coefficient of variation methods. Higher variabilities were related to the targets that are more difficult to reach. Thus, this study determined an optimal sample size between five and eight sets of leaves for spray deposition, and four to five Petri dishes for soil runoff.