Papadakis method and plot size in experiments with lettuce

ABSTRACT:

This study aimed to evaluate the efficiency of Papadakis method in improving quality of the trials in the lettuce crop, establish the best way to estimate the covariate and the optimal plot size to be used in this method. The way of estimating the covariate that allows a better efficiency of the method and the estimation of the plot size adjusted to be used in this method were determined from eight uniformity essays on the lettuce crop. The efficacy of using the analysis of covariance (ANCOVA), using a covariate estimated by the Papadakis method, was tested in an experiment with treatments on the lettuce crop, the variable studied being the aboveground part fresh mass of the plants. The use of ANCOVA with the covariate projected by the Papadakis method improves the quality of the experiments within the lettuce crop. The covariate that provides the best efficiency of ANCOVA is the one that considers a close share of each side of the relative share in the cropping line. The plot size on the cropping line, adjusted to be used in the method, is of four plants (1,2 m) for greenhouse and tunnel and five plants (1,5 m) for the field.

Keywords:
Lactuca sativa; covariance analysis; experimental accuracy; coefficient of variation.