Changes of respiration rate, ethylene evolution, and abscisic acid contentin developing inflorescence and young fruit of olive (Olea europaea L. cv.Konservolia)

Simultaneous measurements of respiration, ethylene production, and abscisic acid (ABA) concentrations, as well as the growth parameters length, fresh weight (FW), and dry weight (DW) of olive (Olea europaea L. cv. Konservolia ) inflorescence were carried out at short intervals (3-7 days) during the p eriod from bud burst until the 3rd week after full bloom (AFB), when young fruit reached 8 mm in length. The axis of inflorescence elongated remarkabl y during the 3rd week after bud burst (ABB), massive bract shedding occurre d during the 4th week ABB, full bloom(FB) was observed 7 weeks ABB, and mas sive floral organ abscission 1 week AFB. The results showed a continuous in crease in inflorescence FW and DW from bud burst until 4 days before FB. Re spiration rate, ethylene production, and levels of ABA were relatively high during the first 3 weeks ABB. After this period, respiration and ethylene followed a similar pattern of changes, inversely to that of ABA concentrati on. An accumulation of inflorescence ABA 6 and 4 days before FB was associa ted with the minimum values of respiration and ethylene production on the s ame dates. The sharp decrease in the ABA concentration during FB and 3 days later was followed by a high rise in ethylene and an increase in respirati on rate, which both rose further 1 week AFB. The results suggest a possible correlation of ABA with the early stage of floral abscission, whereas ethy lene production seems to be correlated with the terminal separatory activit y in olive inflorescence abscission processes.