The cucumber cotyledon greening bioassay for cytokinins was modified by using 95 % acetone-ethanol instead of 80 % acetone as extraction solvent. The cotyledons were extracted directly with a 2:1 (v/v) acetone-ethanol solution in dark for 24 hours, omit ting the homogenization and centrifugation operations of the previous bioassay. The modified bioassay is more convenient and especially useful in screening cytokinin-active substance from a large number of samples.

Key words: cytokinins, cu cum ber cot y le don greening bioassay, chlorophyll ex trac tion, 6-benzyl-adenine, N,N’-diphenylurea

★★★☆☆ Yu XJ, Li GX, Xu D,et al. An Im Provement Of Cucumber Cotyledon Greening Bioassay For Cytokinins[J]. Acta Physiologiae Plantarum,2006,28(1):9-11.