Canopy Spraying of Abscisic Acid to Improve Fruit Quality of Different Sweet Cherry Cultivars

Abstract

Abscisic acid (ABA) plays a major role in promoting ripening in sweet cherry, a non-climateric fruit. Exogenous application of ABA has been performed to study fruit ripening and cracking, but this growth regulator is not used for commercial production. To determine the potential of this growth regulator to improve sweet cherry fruit quality, ABA canopy spraying was assayed in four cultivars. Canopy spraying of S-ABA significantly: 1) enhanced sweet cherry fruit color in ‘Glenred’, ‘Lapins’ and 'Bing' cultivars, but not in ‘Royal Rainier’ (a bi-colored cultivar), and 2) decreased fruit size and firmness in ‘Lapins’, ‘Bing’ and ‘Royal Rainier’. Seasonally reproducible effects were seen in ‘Lapins’ (mid/late-maturing) but not in ‘Glenred’ (early-maturing). Canopy spraying of nordihydroguaiaretic acid (NDGA) decreased color and increased fruit size in ‘Lapins’, but not in ‘Glenred’. Direct application of ABA on fruits attached to the tree, without application to the foliage, increased Lapins' fruit color without reducing size. These results suggest a localized fruit response to exogenous ABA application on fruit color development, but that a decrease in fruit size may be due to the effects of exogenous ABA on the tree canopy foliage.

Transcriptomic and DNA methylation modifications during fruit ripening and in response to ABA treatment in sweet cherry

“…In sweet cherry we recently reported that ABA advances the increase in IAD - a ripening index - in sweet cherry fruits (Kuhn et al, 2021a). Here, we report higher IAD at harvest, similar to other cultivars (Time et al, 2021). Regarding the other ripening parameters, we found reduced size, weight, firmness, and sugar content (Supplementary Fig.…”

“…Therefore, the effect of ABA on fruit sugars seems highly dependent on its influence on leaves and possibly in the source-sink interactions. Regarding softening, fruit firmness is reduced during ripening and in response to ABA (Luo et al, 2014;Ren et al, 2011;Time et al, 2021), which is in line with our results.…”

“…Luo et al (2014) showed that in planta, ABA-treated fruits had a larger size and increased soluble solids content, but it is unclear if the leaves received the ABA treatment. In this regard, Time et al (2021) showed that fruits treated in planta and dipped in ABA solution (thus, excluding the leaves) had fewer soluble solids than untreated samples. Therefore, the effect of ABA on fruit sugars seems highly dependent on its influence on leaves and possibly in the source-sink interactions.…”

“…For the treatment, 400 mg L -1 of ABA solution (commercial product ProTone®, SL - Sumitomo Chemical Chile) was sprayed until runoff to the tree canopy in the late morning. As previously reported, ABA was applied when fruits transitioned from the straw-yellow to the pink stage (Luo et al, 2014; Time et al, 2021). The day of the treatment was defined as the time point zero (T0, 56 DAFB); control trees were untreated.…”