Evaluation of polysorbate 20 and polysorbate 80 as alternative apple thinning agents and their effects on photosynthetic performance : research data underlying the article

Hillmayr, Nika (author), Čebulj, Anka (author), Jakopič, Jerneja (author), Vodnik, Dominik (author), Šircelj, Helena (author), Stopar, Matej (author)

Chemical fruitlet thinning is an indispensable measure in apple production, where chemical agents that can be applied in the later stages of fruitlet development are of particular importance. This research aimed to evaluate the fruitlet thinning efficiency and physiological effects of the emulsifier-based thinning agents polysorbate 20 (P20) and polysorbate 80 (P80) compared with standard thinners. Polysorbates showed effective thinning activity in both experimental years; the effect of P80 was similar to that of ethephon, while P20 had a stronger thinning effect, comparable to metamitron. Based on the results, P20 and P80 could be considered as alternative thinning agents used for late, subsequent thinning. Moreover, polysorbates affected the physiology of apple trees, from which their mode of action can be assumed. P20 inhibited net photosynthesis and stomatal conductance in the leaves of annual shoots and primary spurs. Polysorbates did not alter the maximal photochemical efficiency of PSII. However, they increased the content of xanthophyll-cycle pigments, especially following the application of P20, indicating that polysorbates induced a mild stress response in apple trees. Overall, the stronger thinning effect of polysorbates, especially P20, appears to be linked to reduced carbon assimilation and altered source–sink relationships, which may weaken fruitlet sink strength and promote abscission.

• Language: English
• Keywords: food emulsifiers, apple fruitlet thinning, net photosynthesis, maximal photochemical efficiency of PSII, photosynthetic pigments
• Typology: 2.20 - Complete scientific database of research data
• Geographic coverage: Research data were measured and sampled in the experimental orchard Brdo pri Lukovici, Slovenia (46° 10’ 04.8” N, 14° 40’ 55.2” E).
• Time coverage: Research data were measured and sampled in 2023 and 2024.
• Organization: BF - Biotechnical Faculty
• Year: 2026
• PID: 20.500.12556/RUL-185052
• Data col. methods: Experiment; Experiment: Laboratory; Experiment: Field/Intervention; Measurements and tests: Physical
• Publication date in RUL: 21.07.2026

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: prehranski emulgatorji, redčenje jabolčnih plodičev, neto fotosinteza, maksimalna fotokemična učinkovitost fotosistema II (PSII), fotosintetski pigmenti