Influence of weather conditions on the formation of the components of the chemical composition of cherry fruits

Vasylyshyna O., Postolenko Ye. Uman National University of Horticulture, 1 Instytutska Str., Uman, Cherkasy oblast, 20305, Ukraine Research Station of the Pomology named after L.P. Symyrenko, 9 Symyrenka Str., Mliiv-1 village, Horodyshche region, Cherkasy oblast, 19512, Ukraine e-mail: elenamila@i.ua, evgen780@ukr.net Goal. To determine the influence of weather conditions on the formation of the components of the chemical composition of cherry fruits. Methods. The study was carried out in 2016 – 2018 at the Experimental station named after L. P. Symyrenko of the Institute of horticulture of NAAS with cherry fruit of mid-season varieties Alpha and Pamiat Artemenka. The fruits were harvested in the first decade of July in the consumer stage of maturity. For the fruits they determined the following: the content of dry soluble substances using refractometer RPL3M; the total content of sugars — using ferricyanide method; the content of titrated acids — using titrometric method; the content of ascorbic acid — using iodometric method; the content of tannins and pigments — using the method of Neubauer and Leventhal. Results. Weather conditions at the phase of maturation influence the quality of cherry fruits. Strong and inverse correlation is fixed between the content of dry soluble substances and hydrothermal coefficient of the phase of ripening of fruits of cherry of variety Alpha (– 0,58 ± 0,61) and variety Pamiat Artemenka (– 0,78 ± 0,44). Strong connection (0,94 ± 0,23 and 0.99 ± 0,15) is observed between the content of tannins and pigments and the hydrothermal coefficient in the phase of ripening of fruits of cherry of varieties Alpha and Pamiat Artemenka. An important indicator of fruit quality of cherry is the content of titrated acids. Their formation is influenced by weather growing conditions. In particular, due to the considerable moisture in 2018, compared with 2016 and 2017, the content of titrated acids was higher on 14.5 and 15% for fruits of variety Alpha, and on 14 and 10% — for fruits of variety Pamiat Artemenka. Fall-out during the growing season and in the ripening phase strongly correlated with the content of titrated acids of fruits of varieties Alpha and Pamiat Artemenka with correlation coefficient r=0,81 ± 0.4 and r=0,94 ± 0,23, and r=0,64 ± 0,56 and r=0,39 ± 0,74. Conclusions. Equations of regression are built, which for the titrated coefficient of the ripening phase allow determining the content of dry soluble substances, tannins and pigments in the fruits of cherry of varieties Alpha and Pamiat Artemenka.

When forming fruits, cherries play an important role in temperature resources and humidity. According to the research of M.O. Bagels, low temperatures (−2,4 °C) during flowering reduce the productivity of the variety. Increased temperatures (33−37 °C) and excess rainfall also adversely affect the yield due to damage to the fruit [16].
According to the research of in early ripe varieties, the A.M. Skinder-Barmina cherries last 39−48 days from the end of flowering to mass reaching, 49−57 days in the middle-ripe, 52−65 days in the late-ripe varieties. For full fruiting, sums of active temperatures above 10 °C are required, in which the timing of fruiting cherries of early varieties is 5 days, from June 15 to June 20, medium-matured − 7 days from June 21 to June 28, and late ripening − 14 days from June 29 to 13 July [17 −19].
According to L. Lakatos (2014), J. Revel (2009), the formation of fruit quality of cherries is affected by weather conditions, especially 10-15 days before the formation of the crop [6,7].
In studies by L. Lakatos [5,6] and others the influence of the climatic indicators of the period from flowering to reaching the fruits of cherry is shown: average maximum and minimum temperatures, humidity and their influence on the content of soluble solids, sugars, vitamin C. Studies have shown that increased rainfall during the period of reaching fruits contributed to less dry accumulation. The total rainfall was negatively correlated with the dry matter and acid content of cherry fruits.
The sugar content of the cherry fruit is positively correlated with the temperature of reaching. The higher the temperature (11.5 °C) on reaching, the higher the sugar content of the cherries. At very low temperatures, the sugar content of the cherries is low. In years with sufficient moisture supply, the content of vitamin C is higher [5,6].
According to L. Lakatos, J. Revell, the average temperature in July correlates positively with the soluble solids content, and the precipitation in this month negatively correlates with the total sugar content [6,7].
The purpose of research is to determine the influence of weather conditions on the formation of components of the chemical composition of cherry fruits. To determine the qualitative composition of fruit cherries formed a sample weighing 2 kg of fruits of each variety, collected from 5 trees and different places of the crown. The fruits determined: the content of soluble solids on the RPL-3M refractometer, the total sugar content − ferricyanide method; titrated acids by the titrometric method; ascorbic acid − iodometric method, the content of tannins and dyes in the Neubauer and Leventhal method [20]. Repeat the experiment 3 times. Data were processed by the statistical analysis method of Statistica 6 (Mamchich, 2006) [21].
Research results. During 2016-2018, the agro-climatic indicators during the period of vegetation of cherry fruits differed ( Table 1)  In the achievement phase, this trend is the same: the highest rainfall in 2018 is 36.6 mm, the lowest in 2017 is 23.5 mm.

Agroclimatic indicators for the period of vegetation of cherries
The most complete assessment of the influence of weather conditions on the formation of fruit quality is given by hydrothermal coefficient (GTC). During the growing season it was at the level of 4.3−5.2. It is the highest in 2018 (5.2) and the lowest in 2017 (4.3). During the achievement phase, the indicator was 1.7−2.5.
It is obvious that humidity and thermal resources during the years of research influenced the formation of cherry fruit quality (Fig. 1). In 2017, compared to 2018 and 2016, the solids content of cherries of the experimental varieties Alfa and Memory of Artemenko was higher by 1.8−5.6% and 7−12.12%. This is due to the weather conditions of the reaching phase: a lower sum of temperatures in 2017 (139.7 °C), compared to other years of research (154.2 and 148.4 °C), a small amount of rainfall of 23.5 mm, which led to the lowest SCC among the years under review -1.7. The obtained data also confirm the results of studies by foreign authors [6].
Consequently, temperature and precipitation during the cherry fruiting phase are significantly influenced by the formation of soluble solids content. The correlation between these indicators makes it possible to establish a GTC. For the cherry fruit, during the 2017 growing season, it is the lowest at 4.3, while the highest in 2018 is 5.2. During the phases of achievement, the GTC trend is similar.
The correlation between the chemical composition of cherry fruits and the weather conditions most closely reflects the relationship of these indicators ( Table 2, Fig. 1).   Fig. 1. Content of cherry fruits: a -dry soluble substances (NIR05 = 0.3)   Precipitation during the growing season had less effect on solids and sugars than temperature. For the cherries of the varieties of Alpha and Memory of Artemenko, their number was strongly correlated with the content of soluble solids (r = 0.5 ± 0.67 -0.71 ± 0.49). While the content of sugars correlation dependence is average. During the precipitation phase, a strong inverse correlation dependence with the soluble solids content with a correlation coefficient r = −0.66 ± 0.54 and r = −0.84 ± 0.37 was found.

Correlation between weather conditions and content of some components of the chemical composition of cherry fruits
Between the rainfall during the cherry fruiting phase and the sugar content, the correlation dependence is also strong and reversed (r = −0.79 ± 0.42 and r = −0.89 ± 0.29). The rainfall/temperature ratio makes it possible to more fully determine the effect of climatic indicators on cherry fruit formation. A strong inverse correlation was established between the GTC of the reaching phase and the soluble solids content of the cherries of the Alpha and Memory of Artemenko (r = −0.58 ± 0.61 and r = −0.78 ± 0,44). There is also a strong and inverse relationship between the GTC of the reaching phase and the sugar content (r = −0.72 ± 0.27 and r = −0.84 ± 0.37). An important indicator of the quality of cherry fruits is the content of titrated acids. Their formation is influenced by the weather conditions of cultivation (Fig. 2). In particular, with significant humidity in 2018, compared to 2016 and 2017, the content of titrated acids is higher for the fruits of cherries Alpha varieties by 14.5 and 15%, Memory of Artemenko −14 and 10%.
Precipitation during the growing season and during the reaching phases is strongly correlated with the content of titrated acids of the fruits of cherry Alpha and Memory of Artemenko with correlation coefficients r = 0.81 ± 0.4 and r = 0.94 ± 0.23 and r = 0.64 ± 0.56 and r= 0.39 ± 0.74 (Fig. 3). The GTC of the growing season is also significant (r = 0.78 ± 0.44 and r = 0.57± 0.61).
The content of biologically active substances of cherry fruits depends on the weather conditions of the year of cultivation (Fig. 3). In particular, in 2018, ascorbic acid is accumulated in cherries with high moisture content (36.6 mm) during the reaching and low temperatures phases (148.4 °C), compared to 2016 and 2017 for Memory of Memory of Artemenko and Alpha is up by 1−10% and 5−7%. This is evidenced by the rather high correlation coefficient between the content of ascorbic acid and GTC of cherry fruits (r = 0.63 ± 0.56 and r = 0.72 ± 0.49).
Cherry fruits are valued for their high content of tannins and colorants (see Figure 3). On average, during the years of research, their content in the variety Alpha was 0.8%, in Memory of Artemenko -0.85%. The lowest content (0.6-0.72%) was observed in 2017 with low precipitation during the reaching phases (23.5 mm) and the sum of temperatures (139.7 °C). While in significant rainfall and temperatures in 2018 and 2016, the content of tannins and dyes of the fruit of the Alpha variety is higher by 46−53%, the Memory of Artemenko by 23−30%. The GTC of the achievement phase is quite strong (r = 0.94±0.23 and 0.99±0.15) and indicates a close correlation dependence.
The correlation dependences of the influence of weather conditions on the content of ascorbic acid and tannins and dyes of cherry fruits have been determined by studies of foreign authors [6,7].
A strong correlation between the soluble solids content and the GTC of the period of reaching the fruits of cherry varieties Alpha and Artemenko Memory is revealed, and a regression equation is found, which allows the GTC to determine the soluble solids content (Fig. 4). Because cherry fruits are valuable in the content of tannins and dyes, a strong correlation is found between them and the GTC of the period of reaching. Equations that allow the prediction of the content of tannins and dyes on the basis of GTC are derived.

Conclusions
Weather conditions of the reach phase affect the quality of cherry fruits. A strong and inverse correlation between the soluble solids content and the SCC of the fruiting phase of cherry Alpha varieties (−0.58 ± 0.61) and Memory of Artemenko (−0.78 ± 0,44) was established. There is a strong (0.94±0.23 and 0.99±0. 15) relationship between the content of tannins and dyes and the GTC of the fruiting phase of cherry blossoms Alpha and Memory of Artemenko. The regression equation for which the content of dry soluble, tannic and color substances in the fruits of cherries of the varieties Alpha and Memory of Artemenko can be predicted by the SCC of the achievement phase.