BENZYLADENINE PULSING RETARDS LEAF YELLOWING AND IMPROVES QUALITY OF GOLDENROD (SOLIDAGO-CANADENSIS) CUT FLOWERS

In order to retard early leaf yellowing in flowering shoots of goldenr od (Solidago canadensis cv. 'Yellow Submarine') while preserving overa ll quality, the effects of silver thiosulphate (STS), naphthalene acet ic acid (NAA), gibberellin (GA(3)) and benzyladenine (BA) were investi gated. Except for BA, which was applied by spraying, all compounds wer e applied by pulsing with an aqueous solution for 19 h. STS and BA bot h considerably delayed leaf yellowing in cut spikes during vase life, and the former treatment also inhibited flower senescence; combining S TS and BA was beneficial to both leaf and flower survival. However, si nce BA was inefficient as a pulsing treatment, commercial formulations containing the same active ingredient that did not have this disadvan tage, were examined. The product TOG-L-101 containing BA was particula rly effective in postponing the senescence of both leaves and flowers, and the addition of STS gave no further advantage. A range of concent rations suggested that the equivalent of 45 mu M BA was optimal for bo th leaves and spikes even after simulated transport (dry storage for 2 days at 6 degrees C). TOG-L-101 is thus a nonhazardous and effective substitute for STS, and can be introduced into S. canadensis by normal pulse treatment, which in those circumstances can preserve the qualit y of these cut flowers at the consumer level.