Articles
Efficacy of 1-aminocyclopropane-1-carboxylic acid (ACC) in the thinning of Japanese plums
Article number
1450_13
Pages
95 – 102
Language
English
Abstract
Fruit load adjustment is a common practice in stone fruit to increase fruit size to meet the requirements of export markets.
Currently, fruit load is reduced by hand fruit thinning after the first growth stage. 1-aminocyclopropane-1-carboxylic acid (ACC) as a precursor of ethylene has been tested as a blossom thinner on several stone fruit crops, but there is little information on plums.
During the 2020-2021 season, an experiment was carried out to evaluate the efficacy of ACC applied at different concentrations and application times from flowering to 8-10 mm fruit on two plum cultivars.
In both cultivars, four tree plots, with treatments arranged in a complete randomized design were selected and either 336 or 504 mg L‑1 were applied at white bud (WB), full bloom (FB), petal fall (PF) or 8-10 mm fruit size.
Two treatments without ACC with and without hand thinning were included, to compare efficacy on non-thinned and hand-thinned trees.
At harvest in ‘Black Majesty’, application of ACC at either the WB or FB stage reduced fruit load (fruit m‑2), photosynthetically active radiation intercepted (PARi), while application at the 8-10 mm fruit diameter stage was not effective.
In ‘Candy Stripe’, all treatments decreased fruit load regardless of application timing.
Over-thinning was observed with the application of 504 mg L‑1 applied at FB on ‘Black Majesty’ and at WB on ‘Candy Stripe’. In both cultivars, fruit weight at harvest was dependent on the time of application; early applications of ACC increased fruit weight compared with the hand thinning control, with increases of between 12 and 17% in ‘Black Majesty’ and between 0.5 and 49% in ‘Candy Stripe’. In ‘Candy Stripe’, weight was dependent on the time of application, with the treatments applied at WB showing the greatest efficacy.
Therefore, ACC is presented as an alternative to chemical thinning to be developed in Japanese plum trees.
Currently, fruit load is reduced by hand fruit thinning after the first growth stage. 1-aminocyclopropane-1-carboxylic acid (ACC) as a precursor of ethylene has been tested as a blossom thinner on several stone fruit crops, but there is little information on plums.
During the 2020-2021 season, an experiment was carried out to evaluate the efficacy of ACC applied at different concentrations and application times from flowering to 8-10 mm fruit on two plum cultivars.
In both cultivars, four tree plots, with treatments arranged in a complete randomized design were selected and either 336 or 504 mg L‑1 were applied at white bud (WB), full bloom (FB), petal fall (PF) or 8-10 mm fruit size.
Two treatments without ACC with and without hand thinning were included, to compare efficacy on non-thinned and hand-thinned trees.
At harvest in ‘Black Majesty’, application of ACC at either the WB or FB stage reduced fruit load (fruit m‑2), photosynthetically active radiation intercepted (PARi), while application at the 8-10 mm fruit diameter stage was not effective.
In ‘Candy Stripe’, all treatments decreased fruit load regardless of application timing.
Over-thinning was observed with the application of 504 mg L‑1 applied at FB on ‘Black Majesty’ and at WB on ‘Candy Stripe’. In both cultivars, fruit weight at harvest was dependent on the time of application; early applications of ACC increased fruit weight compared with the hand thinning control, with increases of between 12 and 17% in ‘Black Majesty’ and between 0.5 and 49% in ‘Candy Stripe’. In ‘Candy Stripe’, weight was dependent on the time of application, with the treatments applied at WB showing the greatest efficacy.
Therefore, ACC is presented as an alternative to chemical thinning to be developed in Japanese plum trees.
Publication
Authors
A. Verdugo, S. McArtney, C. Atenas
Keywords
Prunus salicina, ethylene precursor, fruit set, hand thinning
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