INVESTIGATIONS INTO SAMPLE-SIZE FOR ESTIMATION OF CROP DENSITY, SHOOT NUMBER AND EAR NUMBER IN WINTER-WHEAT

Statistical figures concerning biological crop parameters - number of plants per m2, number of shoots per plant, number of shoots per m2 and number of ear-bearing stems per m2 - are reported from four-year plot experiments on winter wheat. The coefficients of variation ranged from 8 to 18 % for the number of plants per m2 and the number of shoots per plant, whereas they were between 10 and 25 % for the number of shoots per m2 and the number of ear-bearing stems per m2. The available data were used to find the adequate sample size for the different accuracies required. Conclusions on crop survey under experimental and farm-scale conditions are discussed.