In agricultural experiments good sampling techniques are important to reduce costs and labor, and guarantee adequate experimental precision. The objective of this research was to study a sampling methodology of experimental plots to evaluate morphologic characteristic and corn yield in maize spikes. Single (DAS 9560), double (AG 6018) and triple (AG 303) crosses corn hybrids and an open pollinated variety (BR 202) were ev aluated. The experiment design was a randomized complete block with four replications and was conducted in the experimental area of the Crop Science Department of the Federal University of Santa Maria (UFSM), Brazil. The main plot was divided in 96 sub plots with one meter of length. In each plot, the spikes of five sub-plots were sampled and length, diameter, grain yield and the mass of one hundred grains of each spike was measured or weighted. It was concluded that the sample size within plots is related to the characteristic to be evaluated in the maize spikes and there are genetic and environment factors that interfere on estimation of sample size of maize spikes. A sample of 24 spikes, one for each split-plot, and six replications for each genotype, results in a considered appropriate precision (less than 10% from the mean) for length and width of spikes, grain yield and mass of one hundred grains.
Zea mays L.; number of replications; split-plot; experimental precision
