SENESCENCE OF CUT LEAVES OF Zantedeschia aethiopica AND Z. elliottiana. PART I. CHLOROPHYLL DEGRADATION

Abstract

Abstract. Chlorophyll degradation occurring during leaf senescence in under control of plant hormones. Changes in the chlorophyll content and the effects of BA (benzyladenine) and GA 3 (gibberellic acid) on this process were analyzed during senescence of cut leaves of Zantedeschia aethiopica Spr. and Zantedeschia elliottiana Engl., two species grown for the florists ’ green. Both growth regulators were applied as 24 h pulse treatment: 0.25 mmol·dm-3 and 0.1 mmol·dm-3 for GA 3 and BA, respectively. Gibberellic acid was more effective than benzyladenine in delaying senescence of both Zantedeschia species leaves by retarding chlorophyll loss. A standard preservative solution used to prolong longevity of cut flowers (8-HQC /citrate of hydroxyquinoline / +2 % S /sucrose/) radically accelerated chlorophyll loss of Z. aethiopica leaves but had no effect on pigment degradation in leaves of Z. elliottiana. However, in both species the preservative diminished the positive effect of GA 3 treatment on final chlorophyll content. Key words: chlorophyll degradation, cut leaves, florists ’ green, gibberellic acid, benzyladenine,