EXPERIMENTS IN FIELD PLOT TECHNIC 9 



PLAN AND METHOD OF INVESTIGATION 



The experiments here reported were designed to obtain informa- 

 tion on several factors affecting the accuracy of preliminary variety 

 and strain tests, with a view to devising, if possible, an improved 

 technic for this important phase of crop improvement work. The 

 data obtained bear directly on the following points: 



1. The extent of error from varietal competition in bor- 

 der rows, and the relation of such competition to the charac- 

 teristics of the varieties, 



2. The relative variability of plots of 1, 3, and 5 rows, and 

 the number of replications necessary for a given degree of 

 precision with plots of the three sizes, and 



3. The effect on variability of adjusting yields by means 

 of check plots. 



Terminology. In this report the term plot will be used to des- 

 ignate an area on which a single variety or strain is grown, in com- 

 parison with other varieties or strains, in other plots. The plot may 

 consist of one or more rows. A plot of more than one row may also be 

 referred to as a block. The single outside rows of the block are the 

 border rows. A single-row plot protected from competition by border 

 rows, which are to be discarded, will be spoken of as a protected 

 single-row plot. A protected single-row plot is therefore a 3-row plot 

 with border rows discarded, and a protected 3-row plot is a 5-row plot 

 with border rows discarded. The phrase "3-row plots replicated five 

 times" will be used to refer to 3-row plots in five systematically dis- 

 tributed locations, not in six. The area on which a complete variety 

 or strain test is conducted is spoken of as an experiment field, or simply 

 a field. A group of plots including one plot of each variety or strain 

 tested is a series. When four replications are used there are four 

 series of plots. The group of contiguous plots from one side of the 

 field to the other constitutes a range. The ranges are separated by 

 alleys. 



Thus the field shown in figure 1 consists of sixteen ranges, each 

 range including twenty-nine 5-row (or protected 3-row) plots. Ninety- 

 six varieties were tested on this field, each replicated four times. 

 Ranges I to IV, inclusive, make up the first series, V to VIII the sec- 

 ond, IX to XII the third, and XIII to XVI the fourth. Each of the 

 four strips running lengthwise of the field and separated by the check 

 plots may also be considered a series. 



All yields are expressed in bushels per acre by weight, computed 

 on the basis of 60 pounds per bushel for wheat, 48 pounds for barley, 



