Frequency of control plots in screening nurseries for protein content

Abstract

Correlation coefficients were calculated in two seasons, between protein content of control plots of "Kyperounda' durum wheat and 'Athenais" barley sown at distances of from 0.6 m to 68.4 m. Simple correlation coefficients were high (0.737, 0.710 and 0.311) and significant at the 1 ~ level of probability for plots 0.6 m apart, but decreased rapidly with increasing distances between plots. The correlation in four nurseries was significant for plots 7.2 m, 4.2m, 4.2 m and 1.8 m apart. It was concluded that a control plot provides a fairly good measure of the protein content of adjacent plots.

Effect of Control Plot Density, Control Plot Arrangement, and Assumption of Random or Fixed Effects on Nonreplicated Experiments for Germplasm Screening Using Spatial Models

“…One of the assumptions in analysis of data from designed experiments is that experimental errors are independent. In agricultural field experiments, however, adjacent plots are often correlated (Hayes, 1925; Griffee, 1928; Briggs and Shebeski, 1967; Hadjichristodoulou and Della, 1975). The presence of the correlation, if uncontrolled, may bias treatment comparisons and inflate residual variation (Grondona et al, 1996).…”