[Great Country Food Policy] For the sake of human sweetness, pineapple gave up "love"

Pineapple has a unique flavor, is cheap, can be peeled and eaten raw, and can also be cooked with other ingredients, which has won the favor of many diners. Many people also found that pineapple seems to have no seeds, unlike watermelon, which spits out seeds while eating, which is a perfect experience! So does pineapple have seeds?

The answer is of course yes!

Where are the seeds in a pineapple?

Pineapple is not actually a fruit in the botanical sense, but a "polymer fruit" developed from more than 200 flowers. We can see that the skin of the pineapple has "small grids" arranged in a spiral shape. Each "small grid" is developed from the ovary of a small flower. Many ovaries are arranged around the inflorescence axis, which is the "hard core", forming a large "fruit". The part we eat is the swollen fleshy inflorescence axis, and the peeled skin is the withered flowers and bracts. When each small flower is pollinated, it will produce corresponding seeds, which are hidden in each "small grid".

Pineapple longitudinal section

For the sake of human sweetness, pineapple "cuts off all emotions and love"

Why is it so difficult to find seeds in the pineapples we usually eat? This has to do with the hummingbird. Yes, it is the smallest hummingbird in the world, but with a very long and thin beak.

Both hummingbirds and pineapples originated in the tropical regions of America. Although pineapple flowers are brightly colored, they are slender in shape and have no fragrance. They are not "attractive" to general pollinators such as bees and other insects. But for hummingbirds, which have an insensitive sense of smell but extremely strong vision, pineapple flowers actually grow into their favorite appearance!

When every little flower is eager to obtain the pollen of "love", the hummingbird will act as the "matchmaker", using its slender and flexible beak to obtain pineapple nectar, help the pineapple complete pollination, and produce the "crystallization of love" - ​​seeds.

After pollination, the pineapple starts the "full-time babysitting" mode, all the nutrients are allocated to the seeds, the ovary is greatly affected, and the pineapple becomes unpalatable. Moreover, the developed seeds are very hard, and if we are not careful, our teeth will be in danger. Therefore, in order for humans to eat the sweet and sour pineapple, the pineapple must give up "love" and no longer accept hummingbird pollination.

Fortunately, there is the isolation of the vast Pacific Ocean and hummingbirds do not like to migrate, which means that as long as pineapples are grown outside of the Americas, they will hardly be pollinated, and humans can eat delicious pineapples with peace of mind.

In addition, in order to keep pineapples seedless, in addition to relying on keeping away from hummingbirds, there is another necessary condition: pineapple flowers are self-incompatible. In layman's terms, pineapples have a built-in mechanism to prohibit "inbreeding", so even if they are accidentally contaminated, they will not be fertilized and grow seeds.

Colorful pineapple flowers

Good news for foodies, but a headache for scientists

For foodies, fleshy and seedless pineapples are very delicious, but this brings a lot of difficulties to the work of breeders.

Since pineapples are not self-compatible and do not have a dedicated pollinator, it is more difficult to develop new pineapple varieties. To cultivate new pineapple varieties, hybrid breeding is required. Without the help of hummingbirds, scientists can only pollinate artificially.

When the pineapple blooms, scientists use pollination sticks to apply the selected excellent male pollen to the pistil of the female pineapple flower. When the pineapple matures, they cut the pineapple to obtain hybrid seeds, and then cultivate the seeds to germinate, bloom, and bear fruit. After obtaining the fruit, scientists will judge the shape and sweetness of the pineapple to determine whether it meets the standards of the new variety.

Without seeds, hybrid breeding would be difficult to carry out. Therefore, in order to create a new variety, scientists need to select parents with excellent traits from millions of pineapples and artificially pollinate billions of flowers to obtain hybrid seeds.

How to reproduce pineapple without seeds?

In order to enjoy its sweet taste for humans, pineapples remain "infertile" throughout their lives. If we, who are far away from America, want to grow pineapples ourselves, we have to wait for the pineapple flowers to bloom, then artificially pollinate and obtain seeds like scientists do. This is undoubtedly a very tedious and lengthy process.

Fortunately, pineapples can be propagated asexually, without seeds and can be "copied and pasted". The simplest method is crown bud propagation. Don't throw away the leftover pineapple heads. After drying, put them in water and wait for them to take root. Then transplant them into the soil and wait for them to bloom and bear fruit. You thought you only bought one pineapple, but in fact you bought many pineapples!

The second method is plant division. A pineapple plant only produces one pineapple fruit, but it will grow many sucker buds and offspring buds, that is, multiple "pineapple heads". When these "pineapple heads" are large enough, they are separated from the mother plant and planted separately, and new pineapples can be obtained. This method is usually used for production.

However, some varieties only produce a small amount of "pineapple heads", which is far from meeting production needs. According to Liu Shenghui, an associate researcher at the South Asian Tropical Crops Research Institute of the Chinese Academy of Tropical Agricultural Sciences, it can be propagated through leaf bud cutting technology, that is, the middle leaves on the crown buds are cut off and cut into suitable growth media to grow into seedlings.

In addition to these methods, certain tissues of pineapple can also be cultured in vitro to induce them to form callus tissue and differentiate into complete plants.

New variety research and development is imminent

For fruit farmers, using "pineapple heads" directly as seedlings for planting saves time and cost in raising seedlings, and achieves stable expansion of pineapples. At the same time, the planting density of pineapples is relatively high, and 3,000 to 4,000 plants can be planted on one acre of land.

High pineapple yields are a good thing, but they can also lead to problems with poor sales. In Xuwen, Guangdong, my country's "hometown of pineapples", hundreds of millions of kilograms of pineapples were ripe but no one was interested in buying them, leaving a large number of ripe fruits rotting in the fields. The reasons for this situation include objective factors such as weather disasters, as well as the single quality structure of my country's pineapples and insufficient improvement in product quality.

The "Bali" variety was introduced to my country for cultivation in the 1920s. It has always been the "first choice" variety for fruit farmers because of its low planting technology requirements and stable yield. However, it has hardly been improved in the past hundred years. In addition, the cultivation standards are not unified, resulting in uneven quality of pineapples on the market, making it difficult to meet consumers' demand for diversified and high-quality pineapple products.

New domestic pineapple varieties are being introduced to the market

In order to cultivate high-quality pineapple varieties with my country's independent intellectual property rights, many domestic agricultural research institutions and enterprises have been constantly exploring and researching, and a number of high-quality varieties have begun to "emerge".

In recent years, the pineapple team of the South Subtropical Crops Research Institute of the Chinese Academy of Tropical Agricultural Sciences has actively carried out pineapple variety selection and breeding, and carried out targeted improvements on my country's pineapple varieties. The "Rennong" series of pineapple varieties developed have the advantages of strong growth, shallow eyes, good yield, and excellent quality, and are suitable for planting in my country's pineapple producing areas.

In order to promote sustainable agricultural development, Chinese scientists and pineapple growers have never stopped researching, developing and promoting new pineapple varieties and new technologies. The "love story" of pineapples is still being written on the red soil of my country's pineapple growing areas.

Author : Wang Ji Research intern at the South Subtropical Crops Research Institute, Chinese Academy of Tropical Agricultural Sciences

Planning : Wu Yuetong, Xie Yun

Co-ordinator : Huang Bingyu

Scientific review : Sun Weisheng, Associate Researcher, South Subtropical Crops Research Institute, Chinese Academy of Tropical Agricultural Sciences

Supporting units : Horticulture Committee of China Tropical Crops Society, National Tropical Fruit Germplasm Resource Garden (Zhanjiang)