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.
The effect of benzyladenine on Astilbe × arendsii Arends flowering was determined. The cultivation of Astilbe × arendsii in an unheated plastic tunnel reduces the inflorescence yield in the first and second year of flowering as compared to the field, but increases the fresh weight and lenght of inflorescence stems.