Nowadays, greenhouse fruits and vegetables have long become a staple of the Chinese diet.
"People are so happy nowadays, with fresh vegetables available all year round, you can eat whatever you want. I remember when we were kids, there were only three kinds of vegetables on the dinner table in winter—cabbage, potatoes, and big radishes. Every summer, we had to make tomato sauce in glass jars. How can we compare to the good fortune of people today," sighed 56-year-old Aunt Song.
Indeed, the natural growth cycle of fruits and vegetables is to sprout in spring, grow in summer, be harvested in autumn, and be stored in winter. But the application of greenhouse technology has overturned this cycle, greatly convenience and enriching people's lives and palates. However, as time goes on, eating these fruits and vegetables always feels like something is missing. "The tomatoes look bright red, but they are neither sour nor sweet. When you cut a cucumber with a flower still attached and spikes on its skin, you can't smell its fresh fragrance. The melon is supposed to be sweet, but it tastes a bit bitter in your mouth..." No wonder many people lament, "The melons aren't fragrant, the fruits aren't sweet, and the vegetables are tasteless." Furthermore, some fruit and vegetable growers, in their excessive pursuit of economic benefits, misuse various hormones and fertilizers, creating discordant notes in greenhouse cultivation. China's greenhouse area accounts for 80% of the global total.
On June 11, a reporter visited a vegetable greenhouse located in Daxing District, Beijing. The greenhouse was filled with vegetables like tomatoes and rapeseed. To make full use of the space, the owner had also set up bamboo poles to grow climbing beans and cucumbers. Due to the recent high temperatures, the plastic covering that was originally on the greenhouse had been rolled up, turning it into an open-air one. Old Wang, the farmer, told the reporter: "Ever since I built these two greenhouses, the variety of vegetables has increased and the yield is higher. The 40,000 to 50,000 yuan I invested has already been paid back."
Chen Diankui, director of the National Engineering Research Center for Vegetables, told reporters that China's current total greenhouse area accounts for 80% of the global total. In northern provinces like Beijing, Hebei, and Shandong, the vegetables produced from December to the following April basically all come from greenhouses. Chen Diankui stated that greenhouse technology allows for artificial control of the environment. For example, watermelons normally grow in summer, but with greenhouse cultivation, they can be ripe in winter. Traditionally, tomatoes should be available on the market in early summer, but with greenhouse cultivation, they can be brought to market as early as spring. In addition, greenhouses can maximize production potential and promote increased output and income for farmers.
But in the summer and autumn, "greenhouse vegetables" are clearly less popular than "open-field vegetables." A person from the Beijing Municipal Bureau of Agriculture said that in winter and spring, out-of-season vegetables account for over 50% of the vegetable supply in Beijing. However, in summer and autumn, the vegetables supplied to Beijing citizens are basically all open-field vegetables. On June 12, reporters saw bustling fruit and vegetable markets at several agricultural markets in Chaoyang District, Beijing, such as Tianshuiyuan and Hongmiao Beili. Mr. Jiang, who is in the fruit wholesale business, enthusiastically said to the reporter: "Except for my watermelons and peaches, which are open-field, 60% of my other fruits are from greenhouses. By July and August, it's basically all open-field fruit. Take watermelons for example, open-field ones sell for 1 yuan each, while greenhouse ones sell for 8 jiao. Although they are more expensive, most people prefer to buy open-field ones because they taste better."
However, any technology has its pros and cons. Greenhouses allow people to eat fresh fruits and vegetables all year round, improving their lives and health. But there are also areas that need improvement. "Good-looking but not tasty" is the most important complaint, as many people said during interviews. Zhang Baohai, a senior agronomist at the Beijing Vegetable Research Center, explained the reason to a reporter from the Life Times. Greenhouse vegetables don't get enough sunlight. Fruits and vegetables grown in the open have ample sunlight and strong photosynthesis, so their mineral content is very rich. In contrast, fruits and vegetables grown in greenhouses have poor ventilation and insufficient sunlight, which reduces surface water evaporation and, consequently, the minerals absorbed from the soil, lowering their nutritional value.
Picking them before they are ripe and then using chemical agents to ripen them. Some vegetable growers, to get their produce to market earlier, pick tomatoes while they are still half-ripe. A spray of "ethephon" will quickly turn the surface red. For growing melons, manual pollination has mostly been replaced by "fruit-setting agents," which makes them grow faster and yield higher, but they can easily go off-flavor if not handled properly. This is the reason why melons can taste bitter. Old Wang bluntly said, "Fruits and vegetables picked early, no matter how bad the taste, can still be sold for a good price. But when fruits and vegetables are available in large quantities later, even if they are delicious, the price is about the same. Everyone does this. To make more money, we can't care whether it tastes good or not, otherwise we won't even recoup our costs."
Reduction in organic fertilizers. In the past, farming relied on manure, and the resulting vegetables were tasty and flavorful. Nowadays, to achieve high yields, farmers often overuse chemical fertilizers, applying too much nitrogen fertilizer. Old Wang admitted: "Organic fertilizers are expensive now, so everyone prefers to use nitrogen fertilizers. Using too much makes the soil less fertile, so the vegetables don't taste good. We don't eat greenhouse vegetables ourselves; we have a separate plot of land to grow our own."
Preference for disease-resistant, high-yield varieties. For example, old tomatoes had thin skin and a rich flavor but were prone to cracking. Now, to facilitate transport and storage, firmer-fleshed seeds are chosen, which results in a much poorer texture.
It is precisely because of the use of various "high-tech methods" that the nutritional value of greenhouse fruits and vegetables is far less than it used to be. Huo Junsheng, director of the Food Science and Technology Department at the National Institute for Nutrition and Food Safety of the Chinese Center for Disease Control and Prevention, made this remark. At the same time, a foreign survey shows that the current sour-sweetness value of tomatoes is 2.77, a loss of nearly 15% compared to the past; and the vitamin C content has decreased by 17 mg compared to 30 years ago. Measurements by food experts show that greenhouse vegetables contain less chlorophyll, vitamin C, sugar, minerals, calcium, and other nutrients than open-field vegetables, while the content of harmful substances like nitrites and arsenic has increased.
Not only that, the chemical hormones added to fruits and vegetables may also cause precocious puberty in children, damage the liver and kidneys of adults, and may even be carcinogenic. When growing fruits and vegetables, nutrition is important.
In the Chinese market, there are always fruits waving the "American flag," such as American Red Delicious apples and American grapes, which look "foreign." But where do the fruits eaten by Americans come from?
In the United States, the reporter noticed that fruits and vegetables are mostly displayed on supermarket shelves, but there are also some farmers' markets. In either case, they have at least undergone preliminary processing—the vegetable leaves are washed clean, and even potatoes are free of soil. Because Americans place great importance on food safety, any quality problem in the market can become big news, so American farmers cannot afford to be careless.
The fruits and vegetables in New York supermarkets are either produced by nearby farms or shipped from California. Among them, there are basically no "greenhouse vegetables," but more and more non-polluting organic fruits and vegetables are available, such as organic mushrooms, whose annual sales have increased by 20%.
However, these organic fruits and vegetables are often "tasty but not good-looking" because they have a longer growth period and are fertilized with natural substances, so they appear "malnourished." "Organic food is healthy and delicious. Since it's for my own consumption, I don't care what it looks like," David, who lives in New York, told the reporter.
In Japan, greenhouses are still used to ensure people can eat fruits all year round. But because the Japanese value the "shun" (seasonality) of their food, the public prefers to buy naturally grown seasonal fruits and vegetables. Some farms in Japan specialize in growing such produce, delivering it directly to homes instead of through supermarkets. The price is high, and the buyers are mostly wealthy and discerning households.
In Israel, despite the extremely harsh natural conditions, the greenhouses in the desert can be called a miracle. They use high-tech technology to achieve the optimal combination of temperature, humidity, carbon dioxide content, and nutrient solution in the greenhouses according to the growth requirements of plants. The light-shading canopies can screen light of different spectral lengths and also prevent pests. Therefore, the taste and nutritional value of greenhouse fruits and vegetables are no inferior to those of open-field ones.
Dutch farmers, to ensure good quality and taste of tomatoes, will sacrifice 20%-30% of the yield.
Facing various fruit and vegetable cultivation technologies abroad, Fan Zhihong, an associate professor at the College of Food Science at China Agricultural University, said: "Chinese people should be satisfied! After all, we need to solve the 'vegetable basket' problem for more than 1 billion people. The fruits and vegetables nowadays are much more abundant than in the past, which is a welcome progress. I have been to some European and American countries, and their fruits and vegetables are not as tasty as those from Chinese greenhouses!" So, how should we choose greenhouse fruits and vegetables? Fan Zhihong suggests, first, don't buy fruits that are not in season. "If a fruit is still half a month away from its ripening period but looks very good, it was likely ripened with agents. For example, a ripened watermelon will have a bright, tender skin, pale stripes, and a green stem."
Second, smell it. Naturally ripened fruits usually have a fruity aroma on their skin; artificially ripened fruits not only lack this fragrance but may even have an off-smell, for instance, a fermented smell."
Finally, if you want to eat out-of-season vegetables in winter, it's best to buy more onions, carrots, eggplants, etc., because they have less pesticide residue. You can use processing methods like light exposure, peeling, and blanching when preparing them. Huo Junsheng reminds that since the nutritional content of greenhouse fruits and vegetables is lower than before, we need to increase our consumption accordingly. For example, the vitamin C from one tomato in the past now requires eating a kiwi at the same time to supplement. The original amount of chlorophyll, calcium, minerals, and other nutrients in a pound of greens may now require a pound and a half or even two pounds to replace, or you can eat some fortified foods or tablets.