Soil heterogeneity often decreases precision in large yield trials. Estimation
of. and adjustment for fertility trends within a trial may increase precision. Two
methods for estimating fertility trends (or spatial variation) are least squares
smoothing and papadakis (nearest neighbor analysis) were evaluated in two
experiments of bread wheat. and compared them with the classical analysis such as
randomized complete block (RCB) and triple lattice designs. Two experiments were
carried out at Gemmieza Research Station in 2001/2002 and 2002/2003 seasons.
The experimental design was 10 X10 triple lattice. Each experiment consisted of a
trial with three replications of 88 lines of bread wheat and 12 local cultivars namely;
(Gemmeiza 3 , G emmeiza 5, G emmeiza 7 , G emmeiza 9 . G emmeiza 10. Giza 164.
Giza 168. Giza 170. Sakha 8. Sakha 61. Sakha 69 and Sakha 93). It could be
summarized that: The results showed that the papadakis method was superior for all
olher used types of analyses in the two seasons. It decreased the percentage values
of experimental error for RCBD from 67.604% and 57.404% to 2.85% and 2.266% in
both seasons .respectively. Lattice was less than least squares smoothing and
papadakis in reduction percentage in EMS. Also papadakis method was more
effective for reducing CV. and raising the precision as other types of analyses. Lattice
and least squares smoothing gave little reduction in CV. Correlation coefficients for
adjusted means for lattice and least squares smoolhing Were more highly with RCaD.
showing that either of these two methods gave similar results in this data set. and the
general rankings of the genotypes were similar RCB means. It could be concluded
that spatial analysis can improve the efficiency of field trials.