It is pure nonsense that seedless grapes are dipped in contraceptives; do not believe it
It is grape season right now, but a video recently spread widely on Weibo and WeChat, making many people “shy away from grapes.” In the video, a man who looks like a “fruit grower” is moving grapes while talking with the person filming, saying that seedless grapes are “dipped in contraceptives.” As the video was forwarded and spread, media reported that sales had already been affected in some seedless grape-producing areas. How are seedless grapes grown? Are they really caused by dipping them in contraceptives? Will eating seedless grapes harm your health? A reporter from the People's Daily “Verification” column conducted interviews and an investigation.
Can applying contraceptives make grapes seedless?
Response: The fruit growers interviewed had never heard of this practice; experts say human contraceptives do not work on plants
In this video circulating online, the “fruit grower” repeatedly mentioned “contraceptives” and, answering the filmmaker's questions, said, “I would not dare give seedless grapes to children to eat” and “eating them will definitely have an effect.”
On Sina Weibo, an officially verified account named “Shijiazhuang Information Express” revealed on August 28 that the video was filmed at a pick-your-own orchard near Shijiazhuang, and that the source was a tip from a fan, whose family member learned of this “inside story” from a fruit grower at the orchard on August 27.
On September 11, the reporter contacted the operator of that Weibo account to ask where the pick-your-own orchard in the video was located and whether the netizen who provided the tip could be reached. The blogger replied: “He refused to be interviewed.” A search on Weibo showed that on August 27, the netizen “Sun-Masked Face” was the first to post this video on Weibo. That netizen replied to the reporter on September 11: the video was provided by a netizen, and “it has already been debunked; the fruit grower's statement is not entirely true.”
To find out the truth, the reporter went to several major grape-producing areas around Shijiazhuang, Hebei. After watching the video, local farmers said the accent of the “fruit grower” in the video sounded local, but this still needed further confirmation.
In Susheng Village, Donglizhuang Town, Jinzhou City, Li Cangying, a large-scale grape grower, said he had never heard that applying contraceptives could produce seedless grapes. The reporter asked agricultural technicians and township officials in Jinzhou, and they also said they had never heard of such a practice.
Can applying contraceptives produce seedless grapes?
Qi Rong, director of the Second Clinic of the Reproductive Medicine Center at Shijiazhuang Maternity Hospital, said that contraceptives can only be recognized by the human body's response recognition mechanism after entering the human body, thereby regulating various physiological indicators in the body and achieving the effect of reducing the likelihood of conception. Plants, however, lack the corresponding receptors and signaling pathways, so contraceptives, which are animal hormones, cannot be recognized by plants or take effect, and simply cannot “contracept” plants.
“The claim about dipping them in contraceptives is absurd.” Nie Jiyun, director of the Fruit Tree Research Institute of the Chinese Academy of Agricultural Sciences and the Ministry of Agriculture's Fruit Quality and Safety Risk Assessment Laboratory (Xingcheng), said that growth regulators used on plants are commonly called “plant hormones,” and their molecular structures are completely different from those of animal hormones. The structures of plant cells and animal cells and the proteins they carry are also completely different. Human contraceptives cannot make fruit seedless, and plant hormones cannot regulate human growth and development.
How are seedless grapes cultivated?
Response: Some use plant growth regulators such as gibberellin, and some use mutant individuals for production; nutritionally they are no different from normal fruit
Ju Huicun, head of the Fruit Tree Station of the Shijiazhuang Municipal Forestry Bureau, explained that the seeds of fruit (that is, the seeds) develop from the plant's ovules, while the fruit (that is, the flesh) develops from the ovary. During the growth and development of fruit, if the development of the ovule is inhibited while the development of the ovary is not affected, seedless fruit can be cultivated.
According to the introduction, there are currently 3 common methods for cultivating seedless fruit. One is to use plant hormone treatment to inhibit seed growth while promoting fruit development; the second is through hybridization, turning diploid plants that could originally produce seeds into triploid plants, hindering normal seed development while providing a certain stimulus so that the fruit itself can produce enough plant hormones to promote its development and promote fruit formation. Seedless watermelon is obtained by this method; the third is to produce seedless fruit by finding mutant individuals in which the plant itself produces sterile seeds but can still produce plant hormones on its own.
Ju Huicun introduced that seedless grapes are a typical example of the first and third types of seedless fruit. For example, for Kyoho grapes, which have the largest cultivation area in China, if a certain concentration of gibberellin is used during the full flowering stage and the young cluster formation stage to inhibit seed development and promote fruit enlargement, seedless Kyoho grapes can be obtained. For grape varieties such as “Jingkejing” and “Dalihong Wuhe,” due to their own variation, after pollination the fertilized embryo sac quickly stops developing, but the fruit itself can produce hormones, allowing the fruit to enlarge and develop into seedless fruit. “Nutritionally, seedless fruit and normal fruit show no obvious difference.” Ju Huicun said.
“The grapes grown are not only for sale; we eat them ourselves too.” Liu Ligeng, a fruit grower in Dushe Village, Tiegan Town, Shenze County, Shijiazhuang City, has grown grapes for nearly 20 years. He said, “For example, for the Summer Black variety, if gibberellin is used during the flowering period, it will become seedless grapes. Many villagers know this.” Liu Hongbo, a fruit grower in Dushe Village, said: “Plant hormones are quite convenient to use, and also cheap. There is no need at all to use contraceptives.”
Nie Jiyun introduced that gibberellin is the most commonly used type of plant growth regulator in seedless grape cultivation and has already been legally registered for use in grape production. Gibberellin is a natural plant hormone. It was discovered in the 1930s by Japanese scientists while studying gibberella infection in rice plants. Later, researchers used fermentation or artificial synthesis for large-scale production, using it on crops such as potatoes and tomatoes to promote growth and sprouting and increase fruit set.
Is gibberellin harmful to humans?
Response: Gibberellin has extremely low toxicity and degrades easily; according to EU standards, an adult would have to eat about 1.8 tons of grapes with gibberellin residues per day for there to possibly be an effect
Because “contraceptives” and “seedless” easily invite associations, many netizens said, “I will never dare eat seedless grapes again.” Will the “plant hormones” used on seedless grapes leave residues, and do they affect the human body?
Wang Zhongyue, a researcher at the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences and director of the Pest and Disease Control Research Office of the National Grape Industry Technology System, said that plant hormones are a class of substances contained in plants themselves that can regulate plant growth, and similar substances can also be synthesized artificially. As long as they are used scientifically, they will increase yield. Even if used unscientifically, they will only affect crop quality, storage and transportation, shelf life, and so on, and will not affect food safety. For such agricultural materials, the Ministry of Agriculture has conducted a large number of scientific experiments and proved that they do not harm humans, animals, or the environment.
Ju Huicun said that even if plant hormones such as gibberellin are eaten by people, they are quickly excreted from the body through metabolism and have no adverse effects on the human body. Moreover, plants naturally produce quite a lot of plant hormones themselves, and eating them will not cause health hazards either.
“Just as animal hormones cannot act on plants, the various plant hormones used in agricultural production cannot regulate human growth and development even if ingested.” Qi Rong said, so there is no need to worry that they will affect children's development.
Nie Jiyun explained that the concentration of gibberellin used when cultivating grapes is extremely low. If the concentration is too high or the amount applied is too large, it will instead damage the plant. Moreover, from application of gibberellin at the flowering stage to grape harvest, two to three months pass, and the gibberellin sprayed earlier has basically all degraded.
Ju Huicun also found in practice that if plant growth regulators are used excessively, they can sometimes cause abnormal plant growth, resulting in problems such as deformed melons, twisted leaves, and brittle stems and vines. But these are all effects on plants, and no cases of harm to the human body have been found so far.
Fruit grower Liu Ligeng said that the amount of gibberellin used is very small, “if too much is used, the fruit branches become hard and the fruit skin becomes thin, which is not good for long-distance transport.”
Wang Zhongyue also said that gibberellin has extremely low toxicity. Many countries internationally grant exemptions for compounds that do not affect food safety after use, and China is drawing on international experience and discussing exemption standards for some plant growth regulators, including gibberellin. The reporter searched for “gibberellin” in the “Pesticide Maximum Residue Database” on the official website of the Institute for the Control of Agrochemicals of the Ministry of Agriculture, China Pesticide Information Network. It showed that among the United States, Japan, Australia, South Korea, New Zealand, and the Codex Alimentarius, only Japan has set a maximum residue level for gibberellin, at 0.2 mg/kg (the website showed the data was updated on May 29, 2012). China's “Maximum Residue Limits for Pesticides in Food” (GB2763—2014), issued by the National Health and Family Planning Commission and the Ministry of Agriculture, does not involve gibberellin.
Nie Jiyun introduced that the current EU standard for the no-observed-adverse-effect level of gibberellin is 3 mg/kg per day. That is to say, a 60 kg adult would need to ingest 180 mg of gibberellin per day for it to possibly affect health. According to the results of grape quality and safety risk assessments by China's Ministry of Agriculture over many years, gibberellin is rarely detected in grapes, and the residue level in detected samples does not exceed 0.1 mg/kg. Calculated according to this figure, a person weighing 60 kg would have to eat 1800 kg of grapes with gibberellin residues every day to ingest 180 mg of gibberellin.