Quantification of ethephon requirements for abscission in olive fruits

Abstract

Ethepon is used commercially in Israel to facilitate mechanical harvesting or hand picking of olive fruits, but the results are often not satisfactory, due to insufficient reduction of the fruit removal force . Studies with 14 C-ethephon were carried out to follow the fate of the applied ethephon from treatment until fruit harvest and to determine the actual uptake and efficiency of the sprayed compound .Only a small portion (less than 3%) of the applied ethephon actually penetrated the target tissue i .e . the pedicels, and released the ethylene responsible for promoting fruit loosening . There was almost no translocation of ethephon from other organs (leaves, fruits) to the fruit pedicels . Extended imbibition in the ethephon solution increased ethephon uptake, which was also enhanced by higher ambient temperatures . Penetration of ethephon varied among different tissues (leaves, fruits and pedicels) . Field applications enabled some calculations of the relationship between the amount of ethephon applied and that actually required to achieve proper fruit loosening . . IntroductionTreatments with (2-chloroethyl) phosphonic acid (ethephon) to enhance fruit ripening have been known for many years [1,17] . More specifically, ethephon has been used to promote fruit abscission and to enable to easy hand picking or mechanical fruit harvesting in cherries [8], apple [11], olive [15], citrus [25], macadamia [16] and many others [17] .In the cited publications, information was given regarding ethephon concentrations and volumes, the components of the spray solutions, climatic conditions at the time of application, and the degree of success achieved in comparison with controls .In order to introduce mechanical harvest of olives (Olea europeae L .), manuals on the use of ethephon were distributed to olive growers [2,3,5] . However, results were inconsistent . Sometimes, treated trees failed to drop their fruits or only 397 partial fruit drop occurred . Complaints were received concerning failure to achieve satisfactory fruit loosening and expense of the method . Satisfactory fruit loosening was achieved mostly when orchards were sprayed with 40001 ha -' , divided into two sprays at an inverval of 20-30 minutes . The concentration of the commercial 'Ethrel' used was 0 .25-0 .3%, which cost $600-720 ha -' in addition to the other expenses of two sprayings . Reductions in ethephon concentrations, or smaller spraying volumes, resulted in fruit removal force (FRF) values too high to ensure satisfactory (> 85% fruit drop) mechanical harvest [4,6,18] . Understanding the reasons for ineffective treatments, and achieving a major reduction in spraying costs, were necessary. Employing 14 C-ethephon to study actual uptake, translocation, rate of ethylene released, and the relationship between these factors and fruit abscission, seemed to be the only solution .

Screening Fruit Loosening Agents for Black Ripe Processed Table Olives

“…The anatomical development of the immature olive fruit abscission zone at the time of commercial harvest may be incomplete (Reed and Hartmann, 1976) or have reduced tissue sensitivity and, thus, the ability to respond to abscission agents (Trewavas, 1986), thereby attenuating or inhibiting response to applied abscission agents. Furthermore, uptake may be influenced by physiological maturity, fruit position, and tissue composition (Ben-Tal, 1992).…”

Mechanical Harvesting of Table Olives: Harvest Efficiency and Fruit Quality

“…Fruit abscission agents as a means of increasing mechanical olive harvest efficiency and reducing the energy required to detach the fruit from the pedicle have been investigated for several decades now (Burns et al, 2008;Martin, 1994;Rosa et al, 2009). In most cases, the effect of the abscission agents is characterized by measuring FDF (Ben-Tal, 1992;Burns et al, 2008;Ferguson et al, 2010Ferguson et al, , 2012Lavee et al, 1982). Little has been published on the effect of abscission agent application relative to both FDF and harvest efficiency.…”

Root Absorption and Xylem Movement of Ethephon in Tomato

“…Worldwide, ethephon is the most widely used PGR and is used to inhibit stem elongation, induce abscission of flower buds and leaves, promote branching, promote flowering of pineapple [Ananas comosus (L.) Merr. ], and accelerate fruit ripening (Ben-Tal, 1992;Cooke and Randall, 1968;Glady et al, 2007;Leatherwood et al, 2009;Miller and Olberg, 2016;Miller et al, 2012;Starman et al, 2004;Turnbull et al, 1999;Yamaguchi et al, 1971).…”