Repeatability and number of measurements for productive variables in vegetable crops experiments

ABSTRACT One of the ways to optimize the evaluation of the experiment and obtain high precision of the results is with the use of an adequate number of measurements for each variable observed in the experiment. In this sense, the objective of this study was to estimate the repeatability coefficient and the number of measurements necessary for the analysis of characters of production of zucchini, cucumber, pout pepper and pea. In the experiments carried out with zucchini and cucumber the variables number of fruits, fruit mass, fruit length, largest fruit diameter and smallest fruit diameter were evaluated. For pea the number, length and mass of pods, number and mass of grains per pod and for pout pepper number and mass of fruits, largest fruit diameter and length were evaluated. The repeatability coefficient (r) was estimated by the principal component method using the correlation matrix and the covariance matrix. The number of measurements for each variable was also determined based on the coefficients of determination of 0.80, 0.85, 0.90, 0.95 and 1.00. The estimated repeatability coefficient obtained the highest estimates using the covariance matrix, ranging from 0.67 to 0.84 for zucchini, from 0.66 to 0.97 for cucumber, from 0.47 to 0.70 for pea and from 0.57 to 0.71 for pout pepper. To evaluate the fruit mass in zucchini, cucumber, pea and pout pepper, are exactly, respectively, 7, 4, 8 and 8 measurements for a coefficient of determination of 95%.