Percentage of Lint in Distributed Plats of Cotton Varieties 1

In a previous paped published in this JOURNAL, the writers show thai when ~o-pound samples taken from a thoroughly mixed bulk of seed cotton are ginned in a 2o-saw experimental gin, the probable error of a single determination is approximately o.2oo% of lint. This is equivalent to e pounds of lint to the acre if a yield of ~,ooo pounds of seed cotton is assumed. It was concluded that one sample will give a sufficiently reliable figure for percentage of lint with which to determine acre yield of lint cotton if the sample is taken from the thoroughly mixed total plat production. In the ~929 cotton variety test at Chillicothe, a ~o-pound sample was ginned from each of four distributed plats of 24 varieties. The percentage of lint of each plat is shown in Table ~. The probable error of a single determination, as computed by Hayes’ "deviation from the mean" method,4 is 0.839% of the.mean. Or, assuming 33.3% of lint as a general mean for all varieties, the probable error is o.279% of lint (33-3% of lint x o.oo839). This is a little higher than the error of o.~oo% of lint found when random samples from a mixed bulk of cotton were ~inned. The difference of 0.079% of lint, however, is equivalent to only o.8 pound of lint to the acre if ~,oo0 pounds again is assumed as the acre yield_of seed cotton. In the previous paper, variation in percentage of lint of successive pickings of a variety was considered. A comparison of Table ~ of that paper and Table z given here shows that successive pickings of a variety are much more variable in percentage of lint than are total pickings from distributed plats of the same variety. Although the yields of the distributed plats of a variety varied considerably (Table i), percentage Of lint was relatively constant from plat to plat. When an experiment is on comparatively uniform land, a percentage of lint figure properly derived from ginning the