Improving of Cherry Fruit Quality and Bearing Regularity by Chemical Thinning with Fertilizer

Abstract

The study’s objective was to evaluate the influence of thinning on the quality and regularity of yield of ‘Regina’ cherries grown on a dwarf Gisela 5 rootstock. The experiments were conducted in the years 2009–2012 in Western Poland. Trees were thinned using a chemical agent, ammonium thiosulphate (ATS), at doses of 20 g ATS L−1, 30 g ATS L−1 and 40 g ATS L−1, and by hand, and the results of chemical and hand thinning were compared with those obtained for unthinned trees. The course of weather conditions in winter and during flowering had a significant impact on yield. Chemical thinning is known to be an effective method to regulate fruiting of pome trees, but it can also be successful if applied to cherry trees, as reflected by the alternate bearing index, which was the lowest after applying ATS at a dose of 40 g. ATS treatment improved fruit quality in full crop years. Thinning resulted in, among other things, larger and darker fruit and higher content of total soluble solids and titratable acidity. Treatment with 40 g ATS L−1 significantly stimulated the vegetative growth of trees.

Plant-Based Biostimulant as Sustainable Alternative to Synthetic Growth Regulators in Two Sweet Cherry Cultivars

“…Plant extracts and plant-derived protein hydrolysates were previously reported to boost C metabolism and to stimulate the biosynthesis of secondary metabolites such as pigments, phenolic comp, and ascorbic acid [66]. Previous studies on sweet cherries demonstrated that inducing an increase in carbohydrate availability for ripening fruits by fruit flower/fruit thinning can result in an increase in soluble solids and anthocyanin concentration and in darker fruit skins [67,68]. Interestingly, the positive effects of the TPEB on soluble solids content and fruit color were not found in the fruits of the cultivar Regina (Table 2 and Figure 2B).…”

Thinning as Method to Regulate Sweet Cherry Crops – a Review

“…fertilizers (ammonium thiosulfate (ATS), urea), and some sulfur compounds [52][53][54][55] [53]. They cause damage to the stigma and anthers, which prevents pollination [56]. Growth regulators, such as hydrogen cyanamide, interrupt dormancy, stimulate uniform development of flower buds, but also cause flower thinning if applied to flowering plants [57].…”

“…In the United States, research has been conducted on the use of cyanoamide, monocarbamide dihydrosulfate, pelargonic acid, endothalic acid and Tergitol TMN-6 as chemical thinning agents. In Europe, studies are carried out on the use of ammonium thiosulfate (ATS) and plant growth regulator 2-chloroethylphosphonic acid (ethephon), which are commonly applied to apple and pear trees during flowering [56,[58][59][60][61][62]. The main objectives of the widespread use of thinning in the cultivation of apples and pears are to improve fruit quality and to prevent alternating bearing [63,64].…”

“…The advantage is that the removal of flowers and buds in the initial period of growth increases assimilation, thereby reducing competition between the vegetative and generative organs of the tree. The result is stronger growth in the year of treatment, better fruit quality, increased yield and greater differentiation of flower buds responsible for flowering in the following year [10,56].…”

“…Thinning can also be optimised by measuring the number of fruit to the branch cross-sectional area ratio. The best fruit quality was obtained with 10 cherries per cm 2 of branch cross-sectional area [56,78]. The selection of the rootstock and thinning have a positive effect on many fruit quality parameters [63,79].…”