Abstract
Our analyses showed that the degree of free fertilization is mostly influenced by maximum temperature and sunshine duration.We found that free fertilization ratio increases with higher daily maximum temperatures; similar results characterise sunshine duration as well, namely we observed higher free fertilization ratio at higher sunshine duration values. Total amount of precipitation during the period between blossoming and maturity and the difference between the average daytime and night temperatures have an important role in the tendency of maturity time. Photosynthesis and respiration are essentially significant in the development of biological systems. These two processes are mostly regulated by the daytime and night temperatures. Therefore, it is not surprising that if the difference between daytime and night temperatures is large, it means intensive photosynthesis and a low degree of respiratory loss. Under these conditions intensive development and ripening can take place; however, in case of a low temperature difference intensive respiration slows down the process of development. Duration of ripening is also significantly influenced by the amount of precipitation of the period between blossoming and maturity.Abundant precipitation slows down the process of ripening, while dry weather accelerates it. Self-fertilization takes place in a space isolated from the environment. In spite of that, we found that effectiveness of self-pollination significantly depends on the meteorological conditions. Degree of self-fertilization is influenced directly by temperature and indirectly by other climatic parameters. We found a significant connection between the values of maximum and minimum temperatures during blossoming and the ratio of self-fertilization. Increase of maximum temperature reduces the effectiveness of self-pollination.A 1 °C increase of maximum temperature reduces self-fertilization ratio by 0,6%. In the case of minimum temperature we can state that the morning minimum temperature of 7,5–8,5°C is the most favourable. If minimum temperatures are under 4 °C or above 12 °C, self-fertilization ratio reduces to the quarter of the value characteristic at 8 °C. We believe that the effectiveness of self-fertilization can be improved considerably by the rational placement of isolator bags within the crown area, avoiding their placement to the external, western crown surface.
Highlights
Free fertilization shows a very close dependence on weather
Fertilization of the ’Pándy’ sour cherry blossoms which were pollinated at different times was observed by Pejkic (1966)
In the case of the observed varieties free fertilization occurred between 5–45% during the period between 1983 and 2008. ’Újfehértói fürtös’ showed the best fertilization ratios ‘Debreceni bôtermô’ was the second best fertilizing variety followed by the ‘Kántorjánosi’ sour cherry variety (Figure 1)
Summary
Free fertilization shows a very close dependence on weather. We can generally state that rainy, cool weather is not favourable for pollination. Fertilization of the ’Pándy’ sour cherry blossoms which were pollinated at different times was observed by Pejkic (1966). He found that the percentage of fruit set was the largest on the first day after pollination and it significantly decreased later. Pollination has to take place at the time of blossom opening or not later than the day in order for the fertilization to be satisfactory. Sour cherry can be classified into the medium early blossoming species, it blossoms the latest among stone fruits (Soltész, 2000). Pollination of sour cherry has to take place within 40 ours after the opening of the blossoms for a satisfactory fruit set
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