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 goldenrod (Solidago canadensis cv. 'Yellow Submarine') while preserving overall quality, the effects of silver thiosulphate (STS), naphthalene acetic acid (NAA), gibberellin (GA(3)) and benzyladenine (BA) were investigated. Except for BA, which was applied by spraying, all compounds were applied by pulsing with an aqueous solution for 19 h. STS and BA both considerably delayed leaf yellowing in cut spikes during vase life, and the former treatment also inhibited flower senescence; combining STS and BA was beneficial to both leaf and flower survival. However, since BA was inefficient as a pulsing treatment, commercial formulations containing the same active ingredient that did not have this disadvantage, were examined. The product TOG-L-101 containing BA was particularly effective in postponing the senescence of both leaves and flowers, and the addition of STS gave no further advantage. A range of concentrations suggested that the equivalent of 45 mu M BA was optimal for both 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 quality of these cut flowers at the consumer level.