EXPERIMENTAL PLAN FOR SINGLE, DOUBLE AND TRIPLE HYBRID CORN

The aim of this study is to determine opti- mal plot size and the number of uniformity trials required to estimate optimal plot size to evaluate cob mass in dif- ferent corn hybrids. Data on the mass of corn cobs was used from 16 uniformity trials for the single hybrid (P32R21), 16 for the triple hybrid (DKB566) and 16 for the double hybrid (DKB747). Each uniformity trial con- sisted of four rows, each six meters long, divided into ba- sic units of one linear meter. The 48 uniformity trials were randomized within the same experimental area. For each uniformity trial, six plot sizes (X) were designed using the sum of adjacent basic units, and the mean, variance and coefficient of variation (CV) were calculated among plots of the same size. CV regression models were adjusted as a function of X, and the optimal plot size estimated. The 16 estimates (16 uniformity trials) for each hybrid were used to estimate the number of uniformity trials required for the experimental area, using the visual jackknife re- sampling approach. The optimal plot size for evaluating corn cob mass is a row five meters long, a size which does not differ between hybrids. The number of uniformi- ty trials (four rows of six meters) required for estimating cob mass and optimal plot size is six, equivalent to 12.5% of the experimental area.