Articles
Plant growth regulators for improving citrus production: Chilean experience
Article number
1457_60
Pages
481 – 490
Language
English
Abstract
The use of plant growth regulators (PGRs) in modern citriculture is a well-established practice.
Countries like Spain, Japan, and the USA have successfully utilized and developed various PGRs over the last three decades within their citrus industries.
However, the strategic programs for PGR application must be adapted to each country’s unique conditions, considering differences in concentration rates, application timings, cultivar responses, behaviors, and industry requirements.
Additionally, rethinking the timing and dosage of application is crucial to avoid residues at harvest.
Common challenges in oranges and mandarins include small fruit sizes and high fruit discard percentages.
In this context, we share our Chilean experience with PGRs aimed at enhancing citrus production, which may benefit other countries facing similar challenges.
Synthetic auxins like 2,4-DP and NOA can improve fruit size when applied during early flower formation and petal fall in ‘Tango’ Mandarin and ‘Fukumoto’ orange trees.
Great thinning responses are observed with 3,5,6 TPA and NAA when applied in the early stages of fruit growth (e.g., 7 mm in ‘Tango’ mandarin). The thinning effects exhibit a rate-moment response, requiring a higher rate as the fruit grows to achieve the same thinning response.
At later stages, such as the end of the June drop, the thinning response decreases, but it enhances growth rates, resulting in larger fruit at harvest.
On the other hand, 2,4-D has demonstrated significant success in reducing winter fruit drop in ‘Tango’ mandarin, a characteristic pre-harvest drop in this cultivar grown in cold climates.
Cytokinins, specifically 6-Benzyladenine (6-BA), sprayed during the flowering process, prove effective in improving fruit size and shifting size distribution curves toward larger sizes without enhancing fruit set.
Abscisic acid (ABA) and 1-aminocyclopropane-1-carboxylic acid (ACC) show a promising thinning effect without any concerns about residues, but the correct rates are still being evaluated.
Countries like Spain, Japan, and the USA have successfully utilized and developed various PGRs over the last three decades within their citrus industries.
However, the strategic programs for PGR application must be adapted to each country’s unique conditions, considering differences in concentration rates, application timings, cultivar responses, behaviors, and industry requirements.
Additionally, rethinking the timing and dosage of application is crucial to avoid residues at harvest.
Common challenges in oranges and mandarins include small fruit sizes and high fruit discard percentages.
In this context, we share our Chilean experience with PGRs aimed at enhancing citrus production, which may benefit other countries facing similar challenges.
Synthetic auxins like 2,4-DP and NOA can improve fruit size when applied during early flower formation and petal fall in ‘Tango’ Mandarin and ‘Fukumoto’ orange trees.
Great thinning responses are observed with 3,5,6 TPA and NAA when applied in the early stages of fruit growth (e.g., 7 mm in ‘Tango’ mandarin). The thinning effects exhibit a rate-moment response, requiring a higher rate as the fruit grows to achieve the same thinning response.
At later stages, such as the end of the June drop, the thinning response decreases, but it enhances growth rates, resulting in larger fruit at harvest.
On the other hand, 2,4-D has demonstrated significant success in reducing winter fruit drop in ‘Tango’ mandarin, a characteristic pre-harvest drop in this cultivar grown in cold climates.
Cytokinins, specifically 6-Benzyladenine (6-BA), sprayed during the flowering process, prove effective in improving fruit size and shifting size distribution curves toward larger sizes without enhancing fruit set.
Abscisic acid (ABA) and 1-aminocyclopropane-1-carboxylic acid (ACC) show a promising thinning effect without any concerns about residues, but the correct rates are still being evaluated.
Publication
Authors
V. Beyá-Marshall, T. Fichet
Keywords
2,4-dichloro phenoxy propionic acid (2,4-DP), 2,4-dichlorophenoxyacetic acid (2,4-D), 2-naphthyloxyacetic acid (NOA), 3,5,6-trichloro-2-pyridyloxyacetic acid (3,5,6 TPA), 6-benzyladenine (6-BA), abscisic acid (ABA), 1-aminocyclopropane-1-carboxylic acid (ACC)
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