ETHEPHON HARVEST EFFECTIVENESS ON OLIVE: SOLUTION pH, TIME OF APPLICATION, AND ADDITION OF BA OR NAA

Abstract

We studied the effect on fruit and leaf abscission of application of ethephon (ETP) at 600 mg liter-1 on excised fruit-bearing olive (Olea europaea L.) shoots held under controlled conditions of temperature and relative humidity analogous to field conditions during fall harvest. Fruit removal force (FRF) and percent leaf drop (%LD) were quantified. Raising solution pH did not improve harvest effectiveness. %LD was significantly higher than control at pH 5, but not at pH 3 or pH 7; FRF was not significantly affected by pH. %LD was not significantly higher than control in the time-of-application treatments (pH 3 only); FRF was significantly less than control when applied at 7AM or 12 noon, but not at 5PM or 10PM. Addition of NAA to the ETP solution raised FRF and lowered %LD; BA had the opposite effect. BA accelerated anthocyanin production on fruits. Regardless of treatment, FRF and %LD are highly but negatively correlated (r2 = 0.62). Harvest effectiveness of ETP use on olive can be defined as a convergence of decreasing FRF and increasing %LD. Mean values for all ETP treatments were FRF = 3.0 N and %LD = 15%, acceptable values for effective olive harvest. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon); naphthalene acetic acid (NAA); 6-benzylaminopurine (BA).