Oops! Why are all the cherries I bought deformed? Is it caused by pesticides?

Too long to read

Don't worry, the appearance of these "twin" cherries is caused by the temperature difference brought by the light. Most of them are fruits on the top of the tree canopy and the sunny branches in the south. It is not the fault of pesticides, so you can eat them with confidence.

“As a tree, the cherry bears all other fruits before it blooms.” With the arrival of summer, domestic cherries (Chinese cherries and Chinese cherries) are available in large quantities, bringing us a sour and sweet enjoyment for our taste buds.

Cherry can be said to be one of the earliest fruits to ripen in early summer in my country. Li Shangyin, a poet in the Tang Dynasty, wrote in "A Hundred Fruits Mock Cherries": "Although the pearls ripen first, the jade flowers bloom early. The warblers are still here, vying to come and kiss them."

While enjoying the deliciousness of cherries, I discovered some interesting plant phenomena. Sometimes, among the cherries I bought, there were "twins" , that is, two fruits fused together on one stalk, and sometimes there was a smaller "baby" on top of the twin fruits . So, what causes this abnormal development of the cherry shape?

Deformed cherries. Photo taken by: Qin Yalong

01

How many varieties of cherries do you know?

Before explaining the variability of cherry fruits, let us first get to know the common edible cherry plants, which mainly include four categories: European sweet cherries , European sour cherries , Chinese cherries and hairy cherries .

1. European sweet cherry

European sweet cherries, also known as cherries, sweet cherries, big cherries and Western cherries, originated in West Asia and Europe. The annual average temperature in the original distribution area is relatively low. It is a temperate deciduous fruit tree. Compared with cherries, its fruit is larger, more durable in storage and transportation, bright in color, and sweet and sour in taste, and is sought after by more and more people.

2. Sour Cherries

European sour cherry, also known as sour cherry, Western sour cherry, is native to southeastern Europe and western Asia. It is cultivated more in Europe, but less cultivated and used in my country. Compared with sweet cherries, its fruit is smaller, but has a unique sour aroma and rich nutrition. In addition to a small amount of fresh fruit, sour cherries are mainly used to make juice, fruit wine and jam, etc. The products processed with it as raw material have good color and flavor.

Sour cherry jam. Copyrighted image from the gallery. Reproduction may result in copyright disputes.

3. Chinese Cherry

Chinese cherry, also known as cherry, has been called Yingtao, Jingtao, Yingzhu, Niupao, etc. According to historical records, seeds of Chinese cherry and Mao cherry were unearthed in the Shang Dynasty tombs in Gaocheng District, Shijiazhuang and the Warring States tombs in Jiangling County, Hubei Province, respectively, which shows that my country has a long history of planting cherry.

Chinese cherries are small in size, which is the most typical difference between them and cherries . Although they taste sweet, they have a fatal flaw - they are extremely intolerant to storage and long-distance transportation. In the days when logistics were not well developed, the taste and appearance of freshly picked Chinese cherries would be very different after just two or three days of transportation.

4. Hairy cherry

Hairy cherry, also known as mountain cherry, plum peach, wild cherry, mountain bean. Unlike the above three types of cherries, hairy cherry is a small shrub, usually no more than 1 meter tall, and the pedicels are extremely short or nearly pedicelless. In the process of the ovary developing into a fruit, the epidermis is completely hairy or only the top or base is hairy.

The hairy cherry is distributed in many provinces of my country, but unfortunately, in Nanjing, although you can see its branches full of flowers every spring, very few of them actually bear fruit.

Hairy cherry. Photo taken by Qin Yalong

Similar to the hairy cherry, spring cherry varieties such as Tsubaki Kanzakura, Okanzakura, Forsythia serrata, Bellflower cherry and Somei Yoshino can also bear fruit, but the amount of fruit is small and the taste is really not good.

Spring cherries. Photo taken by Qin Yalong

So, what kind of cherry are the common cherries on the market?

In fact, cherries are a general term for European sweet cherries and their hybrid offspring . The name comes from the transliteration of the word "cherries".

In addition, the cherries available on the market in my country in early summer are mainly European sweet cherries and Chinese cherries, which are commonly called "big cherries" and "small cherries" because of the difference in fruit size.

They mature relatively early, during which time other similar fruits are less available on the market and there are fewer alternative options to purchase. In addition, cherries themselves have many advantages, such as bright color, crispness and juiciness, which make them popular among people.

02

Cherry deformity affected by high temperature

"Northern fruit moving south" may cause acclimatization problems

It is not difficult to find that these cherries are single fruits under normal conditions, that is, one flower eventually produces one cherry. So, what causes the appearance of deformed cherries?

Cross section of a cherry fruit. Copyright image from the gallery. Reproduction or use may result in copyright disputes.

From a botanical perspective, this is caused by the appearance of multiple pistils during the differentiation of cherry flower buds . The genus Prunus, to which cherries belong, has only one pistil, one carpel, and one chamber, with two ovules in each chamber.

As a stone fruit, only one of the two ovules of cherry can normally develop into a seed. Of course, there are exceptions. For example, when you eat apricots, you may occasionally find two seeds wrapped inside. When you eat almonds, you may also encounter the situation of "one seed and two seeds". These are the result of two ovules developing at the same time.

Most of the deformed cherries are conjoined double fruits, that is, the two fruits are tightly attached, and each fruit contains a seed.

At this time, the cherry flower has 2 pistils, 2 carpels, and 2 ovaries. During the development of the fruit, the 2 carpels fuse together to develop into twin ovaries, and the two fruits also grow close together.

Conjoined triple fruits are a degenerate fruit residue attached to a fused double fruit, which is caused by the fusion of three carpels and the failure of one of them. Fruit shape variation will seriously affect the appearance quality and commodity value of cherries, greatly damaging the economic interests of growers.

Most of the cherries grown outdoors in China enter the physiological differentiation period of flower buds after the new shoots stop growing in May. From July to August, flower bud differentiation will change from vegetative growth to reproductive growth and enter the morphological differentiation period. The order of differentiation is the initial differentiation period, bud primordium differentiation period, calyx primordium differentiation period, petal primordium differentiation period, stamen primordium differentiation period and pistil primordium differentiation period.

Studies have shown that during the flower bud differentiation period, especially the differentiation period of sepals and petals, if the temperature is above 30°C, without human intervention, the incidence of deformed fruits in the second year will increase greatly, and as the temperature rises, the proportion of conjoined double fruits will also be higher.

However, in early and mid-July, the temperature in warm areas of my country often exceeds 30°C. This is the differentiation period of cherry sepals and petals, and such a high temperature environment can easily lead to the formation of double or even multiple pistils.

However, in the later stages of flower bud differentiation, such as the stamen primordium differentiation stage, even high temperatures will not affect the incidence of deformed fruits.

The incidence of deformed cherry fruits is closely related to the high temperature weather in the previous year, which has become the main obstacle to the "north-south migration" of cherries. The summer in the south is generally hot, and the cherry fruits cultivated there are seriously deformed, and the yield is greatly reduced.

In addition, as a deciduous plant, cherries need a certain number of hours of low temperature in winter to go dormant, but the relatively high temperature in the south makes it impossible for them to dormant normally, and the yield and quality of the fruit will also be affected.

Cherries. Copyrighted images from the gallery. Reproduction may lead to copyright disputes.

Cherries are not only demanding on the environment during the stage of flower bud differentiation, but also very delicate when they bloom. In severe cold weather, the flowers will be directly frostbitten . In high temperatures, the embryo sac and ovules will quickly degenerate a few days after the flowers bloom. Sometimes, the ovules have already lost their vitality before the pollen arrives, and abortion is inevitable. The higher the temperature, the easier it is for the ovules to age, the more serious the embryo sac abortion, and the more difficult it is to set the fruit.

03

Keeping a Cherry Tree Alive

How many hurdles do we have to overcome?

As the saying goes, "Cherries are delicious but the trees are difficult to grow." If you want to eat plump and round cherries, you have to work hard behind the scenes.

In order to increase the commercial value of cherries and reduce the occurrence of deformed fruits as much as possible, it is necessary to select suitable varieties before planting. The incidence of deformed fruits of different varieties in the same region is different, and the incidence of deformed fruits of the same variety in different regions is also different. Therefore, it is very important to find varieties suitable for local cultivation and market demand.

Long-term observations have found that the proportion of deformed cherries in the field is significantly higher at the top of the crown and on the sunny branches in the south. This should be caused by the temperature difference caused by light. Therefore, in the planting process, in order to prevent fruit deformities, it is necessary to pay attention to the regulation of temperature during the differentiation period. In the hot summer, short-term artificial shading, treetop sprinkler irrigation and other measures can be used to effectively reduce temperature and radiation intensity.

In recent years, artificial cultivation in facilities has created a suitable environment for the growth of cherries and changed the normal physiological cycle of cherries, which has not only enabled the fruits to be put on the market earlier, but also advanced their flower bud differentiation period, thereby effectively avoiding the high temperatures in summer and reducing the incidence of deformed fruits.

Of course, if you find deformed flowers and fruits on the cherry tree, just pick them off in time. This will not only allow the tree to supply nutrients to other normal fruits, but also ensure the quality of the fruit.

In addition, cherries are shallow-rooted plants. In addition to being intolerant to high temperatures, they are also very intolerant to waterlogging. Therefore, it is best to choose ridge cultivation when planting to ensure that the cherry trees are not flooded.

Studies have found that soil drought can cause double fruit in peach, apricot and other fruit trees, but by artificially controlling soil moisture, dry soil will not affect the proportion of deformed cherries.

Other studies have pointed out that during the flower bud differentiation period of cherries, exogenous plant growth regulators can control the occurrence of cherry deformed fruits. For example, the application of 6-benzylaminopurine and ethephon will increase the incidence of double pistils, while the application of naphthaleneacetic acid, abscisic acid and gibberellin will reduce the incidence of double pistils. However, it should be noted that the occurrence of deformed fruits is not caused by the use of pesticides.

At present, after years of cultivation and planting, there are many varieties of domestic cherries on the market. In addition to being differentiated by size, cherries can also be divided into three varieties according to different maturity periods: early-ripening, mid-ripening and late-ripening, and can also be divided into three categories according to the color of the fruit: purple-black, bright red and yellow.

Cherry mix. Copyright image. Reprinting may cause copyright disputes.

Yellow cherries are the new favorite in recent years. You can buy both the imported variety "Rainier" and the domestic variety "Yellow Curling" on the market. The flesh is golden in color and the skin is red with yellow inside, just like a piece of blush. The skin is thin and the flesh is crispy. When you bite it, the unique aroma of the flesh will burst in your mouth along with the juice, leaving you with an endless aftertaste.

However, although the colors of various cherries are different, the nutritional components of the fruits are generally the same. The color of their fruits is mainly caused by the different contents of anthocyanins and lutein in the fruits. When the anthocyanin content is high, the fruit tends to be purple-red, and when the lutein content is high, the fruit tends to be yellow.

04

Bugs Hidden in Cherries

Salt water soaking is safer

When washing cherries, you may occasionally find small white worms crawling out of the surface of the peel. Why does this happen?

This is because young cherries contain a lot of tannins, which taste very astringent. As the fruit matures, the tannins gradually decrease and the soluble sugar increases. While arousing our appetite, it also attracts insects to enjoy the deliciousness of cherries.

Tiny fruit flies are one of them. They lay eggs on cherries, but when stimulated by the salt water soak during washing, the fruit fly larvae will crawl out one after another.

Some people may ask, will eating food without washing or after simple washing cause physical discomfort?

Don't worry too much about this. First, the amount we eat each time is limited. Second, these larvae have been eating cherry pulp since they hatched, which is non-toxic and harmless. We eat it as a protein supplement.

However, to be on the safe side, it is best to soak cherries in salt water for about 20 minutes before eating. Recently launched bayberries also contain fruit fly larvae, so it is recommended that you soak them in salt water before eating.

Finally, I would like to give a shout-out to Chinese cherries. As a fruit, Chinese cherries are unique among many cherries. More and more domestically produced cherries are gradually entering thousands of households. This not only satisfies the taste buds of the people, but also drives the local economy. How can we not love them?

Produced by: Science Popularization China

Author: Qin Yalong, Institute of Botany, Chinese Academy of Sciences, Jiangsu Province

Producer: China Science Expo

The cover image and the images in this article are from the copyright library

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