Determining the right moment to start harvesting plums is crucial because it directly affects the quality of the fruits, their transportability and storage capacity. It is important to determine the optimal time for each variety, avoiding premature or late harvesting. B.Sc. Eng. Mihajlo Žikić, expert associate for fruit growing and viticulture in the PSS service in Zaječar, emphasizes the importance of this procedure for “Good Morning”.
Source: Serbia in the frame
Žikić explains that premature harvesting is harmful because the fruits do not reach the required size, characteristic color and optimal quality. On the other hand, a late harvest is not desirable because the fruits drop more, are more susceptible to mechanical damage and bear transport less well due to increased transpiration and increased sensitivity to physiological diseases.
Plum and its maturity: differences in fruits
During fruit ripening, there are two stages of maturity: botanical and full maturity. Botanical maturity is reached when the plum reaches the size characteristic of its variety, and its seeds become capable of germination. At this stage, further inflow of nutrients ceases. The fruit is ripe on the outside, but not yet suitable for fresh consumption.
Full maturity means that the fruit has gone through complex biochemical processes and has the best organoleptic properties, such as taste, aroma and juiciness. The fruits are then most suitable for fresh use and all forms of processing.
Engineer Mihajlo Žikić from the PSS service in Zaječar explains that technological maturity, which is important for fresh consumption and processing, usually coincides with full maturity. This is the phase in which the fruit is of the highest quality and most suitable for use, characterized by a change in the color of the skin of the fruit and the appearance of a wax coating. The color of the fruit becomes intensely blue or corresponds to the varietal characteristic, and the fleshy part changes from greenish to golden yellow. Fruit yield increases significantly until ripening.
How to determine the degree of maturity?
For experienced fruit growers, determining the degree of maturity is not a difficult task. In practice, several methods are used to determine the optimal harvest date, which means the middle date when the harvest should be organized. The optimal moment of harvesting a certain variety does not mean that the entire plot can be turned in a short period of time.
The ripeness of the fruit can be recognized by the separation of the fruit with the stem from the branch, the change of the primary and secondary color of the skin, the change of the color of the seed, the iodine-starch test that shows the disappearance of starch, the determination of the firmness of the flesh of the fruit, the refractometric index and other methods.
Žikić points out that refractometers, digital or manual, which work on the principle of refraction of light, are increasingly being used. The amount of soluble dry matter is determined by a manual refractometer or a table-top Abe refractometer, where the squeezed filtered or centrifuged juice is taken and applied to the refractometer to read the value in percentages. Values vary by variety, so the “Stanley” variety has 16.2 to 18 percent, the “Cačanska rodna” 19.6, and in some years it can reach up to 22 percent. For other plum varieties, the percentages range within these limits.
Žikić emphasizes that plum fruits should not be harvested before botanical maturity, as this would lead to a lower yield and loss of typical varietal characteristics, accelerated degradation and the appearance of physiological diseases.
Source: Good morning
Source: boljazemlja.com
