20.500.12556/RUL-185052 Evaluation of polysorbate 20 and polysorbate 80 as alternative apple thinning agents and their effects on photosynthetic performance research data underlying the article 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. food emulsifiers apple fruitlet thinning net photosynthesis maximal photochemical efficiency of PSII photosynthetic pigments prehranski emulgatorji redčenje jabolčnih plodičev neto fotosinteza maksimalna fotokemična učinkovitost fotosistema II (PSII) fotosintetski pigmenti true false false Angleški jezik Slovenski jezik Research data were measured and sampled in the experimental orchard Brdo pri Lukovici, Slovenia (46° 10’ 04.8” N, 14° 40’ 55.2” E). Research data were measured and sampled in 2023 and 2024. Neznano 2026-07-21 19:31:36 2026-07-21 21:01:50 2026-07-22 04:04:20 0000-00-00 00:00:00 2026 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 Methodology.docx Methodology.docx Methodology 1 8F8EAAB6AD18AE92CF6EE0355F56CA62 a5eaba00741d29de7992781753c362cabcc03faaf771ba7c098ec8dc12a279b0 d68a8776-8529-11f1-9b0d-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=243092 Original_data.xlsx Original_data.xlsx Original data 1 AD4E80C2A6A22598F1D48EDBBEF26A11 9afa07ec96335a3ac20e762335c9eea44406ab6003f7e7dd78a8a041d22a5808 d5180c9d-8529-11f1-9b0d-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=243091 Biotehniška fakulteta Poskus Poskus: Laboratorij Poskus: Teren/Intervencija Meritve in testi: Fizično 0 0 0