EN
The cucumber cotyledon greening bioassay for cytokinins was modified by using 95 % acetone -ethanol in stead of 80 % acetone as ex traction solvent. The cotyledons were ex tracted directly with a 2:1 (v/v) ac e tone-ethanol solution in dark for 24 hours, omitting the homogenization and centrifugation operations of the previous bioassay. The modified bioassay is more convenient and especially use ful in screening cytokinin-active substance from a large number of samples.