Katia Alves Campos

Tamanho ótimo de parcela para experimentos com rabanetes

Optimal plot size for experiments with radish The establishment of optimum plot size, in any culture, is one of the ways to increase experimental precision and maximize the information obtained in an experiment. The aim of this study was to determine the optimum size of plots for experiments with radish for the variables mass and root diameter. A test of uniformity was conducted with the planting of radish carried out in lines spaced at 15 cm to 5 cm between plants. The basic unit was defined as a linear segment of three consecutive plants. After 30 days of planting, mass (g) and diameter (mm) of radishes were evaluated. We simulated 35 sizes of plots, estimating mean and coefficient of variation for each size of plot and, using different nonlinear models, we determined the optimum size of plot for assays with radish. It was observed that the methods of modified maximum curvature and targeted linear and quadratic response models estimated different sizes of plot; therefore, in experiments with radish culture, plots with 21 to 63 plants (0.1575 to 0.4745 m²) per plot are recommended.

Alternative for the evaluation of coffee seedlings using Fisher’s discriminant analysis

One of the applications of Fishers linear discriminant function (FDF) is its use in transforming multivariate data into a new univariate variable. This then makes possible a new option for the variance analysis of multivariate data, in addition to the multivariate analysis of variance (MANOVA). The aim of this work was to select groups of seven characteristics of quality in coffee seedlings using six criteria for selection, to use the FDF to transform such groupings of characteristics into a new variable, and then to compare interpretation of the results obtained from the univariate and multivariate analyses of variance of the characteristics and this new variable, with a view to its use in evaluating coffee seedlings. A randomised block design was used to assess the effect of organic fertiliser on the formation of seedlings in coffee cv. Catuai Vermelho IAC-44, evaluating the following characteristics: seedling height, diameter, root length, dry weight of shoots and roots, leaf area, number of leaves and total dry weight. According to the selection criteria used, different subsets of the selected characteristics are possible. The use of the FDF is shown to be viable in discriminating between treatments. Univariate analysis of the new variable obtained with the FDF and multivariate analysis (MANOVA) was able to detect differences between the treatments, however, it is simpler to apply FDF methodology.