caa a22 4500 445841869 CHVBK 20180317145347.0 cr unu---uuuuu 170323e20111101xx s 000 0 eng 10.1007/s10725-011-9606-x doi (NATIONALLICENCE)springer-10.1007/s10725-011-9606-x Regulation of source: sink relationship, fruit set, fruit growth and fruit quality in European plum ( Prunus domestica L.)—using thinning for crop load management [Elektronische Daten] [Claudia Seehuber, Lutz Damerow, Michael Blanke] Demand for large fruit of uniform size is increasing in the market; thinning is a means to achieve consistently large fruit and to overcome possible alternate (biennial) bearing for the small-fruited European plum (Prunus domestica L.). However, chemical thinning agents for stone fruits are scarce and/or often ineffective. Hence, the objective of this work was to study possibilities of enhancing fruit growth and to improve fruit quality, viz size using plum as a model crop. Nine-year-old ‘Ortenauer' plum trees, trained to spindles, with maximum flowering intensity (score value 9) near Bonn, Germany were mechanically, chemically or hand-thinned. Un-thinned plum trees in the same rows served as control. Trees were either mechanically thinned at full bloom on 20 April 2009 with a rotor speed of either 300, 400 or 500rpm, and half of those trees additionally treated with ATS (15L/ha) and an ethylene releasing compound 35days after full bloom or manually thinned. The objective of 1/3 flower removal was successfully achieved even with the slowest rotor speed of 300rpm. The number of fruit per branch was significantly reduced from 152 to 67-76, equivalent to a (source: sink) leaf: fruit ratio of 5:1. Mechanical thinning significantly enlarged fruit mass from 28g in the un-thinned control to 30-32g with rotor speeds of 400 or 500rpm. Additional chemical thinning with ATS and an ethylene-releasing compound resulted in no further increase in fruit mass. Inner fruit quality (sugar) of the plums appeared unaffected by either mechanical or chemical thinning, except for fruit firmness: Plums thinned with an ethylene releasing compound were softer and ripened earlier than respective control fruit. The most efficient method of flower removal and fruit mass enlargement was mechanical blossom thinning with 400rpm, which may provide a suitable replacement for chemical and/or manual thinning. Alternatively, the mechanical thinning can be combined with either of those options. Mechanical blossom thinning was as effective to overcome or avoid alternate/biennial bearing as the ethylene releasing compound in the previous year. The results are discussed with respect to stone fruit being more difficult to thin than pome fruit, because the former do not exhibit leaves at the time of blossom thinning. Stone fruits develop within a shorter time and a larger number of (smaller) leaves (source) are required for the same fruit growth and final fruit size (sink). A lower threshold of fruit removal has to be exceeded before the remaining stone fruit grow faster and final fruit mass and sugar (and possibly fruit firmness) increase, while acidity remains unaffected by fruit set. An upper saturation threshold is reached fairly quickly without further effects. Springer Science+Business Media B.V., 2011 Alternate bearing nationallicence Ammoniumthiosulfate (ATS) nationallicence Ethylene nationallicence Fruit growth nationallicence Fruit quality nationallicence Fruit set nationallicence Naphtylacetoacid (NAA) nationallicence Prunus domestica L nationallicence Sustainability nationallicence Thinning nationallicence Taste nationallicence Seehuber Claudia Institute of Agricultural Engineering, University of Bonn, Nussallee 5, 53115, Bonn, Germany aut Damerow Lutz Institute of Agricultural Engineering, University of Bonn, Nussallee 5, 53115, Bonn, Germany aut Blanke Michael INRES, Department of Horticultural Science, University of Bonn, Auf dem Hügel 6, 53121, Bonn, Germany aut Plant Growth Regulation Springer Netherlands 65/2(2011-11-01), 335-341 0167-6903 65:2<335 2011 65 10725 https://doi.org/10.1007/s10725-011-9606-x text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10725-011-9606-x text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Seehuber Claudia Institute of Agricultural Engineering, University of Bonn, Nussallee 5, 53115, Bonn, Germany aut NATIONALLICENCE 700 1- Damerow Lutz Institute of Agricultural Engineering, University of Bonn, Nussallee 5, 53115, Bonn, Germany aut NATIONALLICENCE 700 1- Blanke Michael INRES, Department of Horticultural Science, University of Bonn, Auf dem Hügel 6, 53121, Bonn, Germany aut NATIONALLICENCE 773 0- Plant Growth Regulation Springer Netherlands 65/2(2011-11-01), 335-341 0167-6903 65:2<335 2011 65 10725 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer