EFFECT OF LIGHT QUALITY ON ETHYLENE FORMATION IN LEAF AND PETAL DISKSOF BEGONIA X HIEMALIS-FOTSCH CV SCHWABENLAND RED

The effect of different light qualities (blue, green, white, red and f ar-red) on ethylene production in leaf discs and flower petal discs of Begonia x hiemalis cv. Schwabenland Red was studied. All the light qu alities, except far-red, reduced the ACC-conversion to ethylene in lea f discs by about 70% at a photosynthetic photon flux density (PPFD) of 20 mumol m-2 s-1. Blue and green light were less inhibitory than whit e and red light at lower PPFD. In all treatments far-red light at 0.5 mumol m-2 s-1 of photon flux density (PFD) stimulated the ACC-conversi on to ethylene in leaf discs by about 60-90% compared to the dark-incu bated control. White and red light strongly inhibited the alpha-naphth alene-acetic acid (NAA) stimulated ethylene synthesis in leaf discs. T he results may suggest that the ethylene production is controlled by p hytochrome in the leaves but not in the petals. Lack of coaction of an y light quality with silver ions on ethylene production in leaf and pe tal discs was also observed.