Effect of growth retardants on flower longevity and the onset of leaf yellowing and necrosis on Gloriosa 'fire bird'

Flower longevity and the onset of leaf yellowing and necrosis in Gloriosa were investigated using some plant growth regulators application such as BA, GA(3)+BA, ethephon, and STS pulse-treatment. At seven days after anthesis of flower development stage, pretreatment with these substances bad no effect on flower longevity. Thus, Gloriosa flowers appeared to be ethylene insensitive for flower senescence. However, leaf yellowing occurred following ethephon and STS application. GA(3) and GA3+BA treatments resulted in dark green foliage, but in BA pretreatment, leaf necrosis occurred. Anatomical study of leaves with GA(3) and GA(3)+BA treatments, palisade and spongy tissue became compact and starch grains and chloroplasts increased as flower development proceeded. As with BA, leaf epidermal cells (both adaxial and abaxial) thicken and breakdown. Tannins or lignin deposition was observed in the palisade and spongy tissues. Our observations suggest an association between the localized accumulation of condensed tannins or lignin and appearance of the dark-stained spots that precede the necrotic lesions in Gloriosa leaves following BA treatment.