Involvement of ABA in postharvest life of miniature potted roses

Exogenous application of ABA (abscisic acid) to intact miniature potted ros e plants (Rosa hybrida L.) resulted in deterioration of postharvest quality of two cultivars. Spraying with ABA increased leaf drop and accelerated fl ower senescence in 'Vanilla' and 'Bronze', while bud drop was only induced in 'Bronze'. Application of ABA to detached rose flowers accelerated their senescence, indicating that the observed senescence promoting effect was no t a secondary response resulting from ABA-induced leaf senescence and absci ssion. ABA-treatment increased ethylene production in 'Bronze' flowers, whi le no ethylene production was measured in flowers of 'Vanilla', or in the l eaves of both cultivars. Pre-treatment with 1-MCP (1-methylcyclopropene) de layed ABA promoted flower senescence in 'Bronze', suggesting that the effec t of ABA is at least partly mediated by ethylene. The senescence promoting effect of ABA on leaf drop and flower life of 'Vanilla' flowers was not cou nteracted by 1-MCP pre-treatment. The cultivar 'Vanilla' had a low ABA leve l at all flower stages, while ABA content of the 'Bronze' petals was high i n buds, lower in open flowers, and increased during flower senescence. An i ncreased ABA content after ethylene treatment in 'Vanilla' suggests that et hylene, natural or exogenous, can increase ABA levels of flowers.