In the Research and Breeding Base for Platanus of Huazhong Agricultural University (HZAU), rows of plane trees thrive in breeze, without the mess of the trees’ fruits or flying hairs. Prof. Bao findings with pride, “The No. 13 plane tree is our new variety, named ‘HZAU Qinglong’. Now the tree has a trunk diameter of 21cm. It also has the advantages of thick branches, less twigs and fast growing speed. Last year it only produced 80 fruits, greatly reducing the flying hairs.”
As one of the “world’s five major street trees”, Platanus, or plane tree, is renowned as the “king of street trees” due to its wide distribution and high demand. With its broad crown providing shade, the plane tree also possesses the excellent qualities of resistance to pruning and pollution, and adaptability to different soil types. Therefore, plane trees are extensively planted across China, which have become a beautiful landmark, and even a unique symbol in some cities.
The almost “perfect” plane tree, however, also has a “flaw” -- its annoying hairs shed from every April to June, which would cover the whole city, causing some diseases like allergies and upper respiratory infections. Many rhinitis sufferers are constantly troubled by it.
How to deal with the issue? Prof. Bao and his team have spent thirty years on it.
In 1984, fresh from university, Bao came to work at HZAU (Huazhong Agricultural College then). It’s the shade of plane trees along the road that brought him pleasant coolness in that hot August, which gave Bao the first fond impression of the trees and inspired him to make Platanus the subject of his future research. In 1993, he began to study on the issue of plane trees’ hairs.
The flying hairs of plane trees mainly come from its bursting fruits and the back side of its leaves. One day an accidental inspiration urged Prof. Bao to count the number of hairs inside one fruit of the plane tree. He came to a surprising result: One of the fruits had over 1400 seeds inside, with about 300 hairs on each seed.
“According to our calculations, an ordinary mature plane tree produces nearly 1,000 fruits per year, the burst of which could result in 300-400 million flying hairs, not including the ones from the leaves,” said Prof. Bao. “Our goal is to cultivate plane trees with fewer fruits and hairs, or even no hair.”
Having learned about many other countries’ experience, Prof. Bao points out that most European countries choose to control the plane tree hairs through pruning, which leads to lower aesthetic value, smaller shade and higher costs.
In the beginning, in order to select the plane trees with less fruits and hairs, Prof. Bao and his students checked all the trees one by one, leaving marks on the satisfactory ones for observation in the following year.
Up to now, with over 500 special germplasm resources they collected, Prof. Bao’s team have cultivated seven new Platanus varieties with national plant variety rights, through methods including seed introduction, cuttage, grafting, selection, and polyploid breeding. Compared with the traditional ones, those new varieties can reduce 80%-90% flying hairs.
Prof. Bao explained, “For example, compared with the traditional ones, our new variety ‘HZAU Qinglong’ grows vigorously with 90% fewer flying hairs, which suits the residential areas well; Besides, compared with the rough leaves of traditional ones, the new variety ‘HZAU Lifeng’ has glossy leaves in a similar shape with maple’s. It has 80% less flying hairs, a good choice for street trees...”
Nowadays, through planting and grafting, more than ten cities in China are experimenting and promoting the new varieties of plane trees.
During the thirty years of research, Prof. Bao has encountered numerous challenges and adversities. Agricultural research, however, has been regarded as his lifelong pursuit which requires both passion and perseverance. In his sixties, Prof. Bao will continue to work for his dream that Platanus could become a “perfect” street tree, allowing citizens to enjoy its shade without the disturbance of flying hairs.
Source: http://news.hzau.edu.cn/2023/0515/66535.shtml
Translated by: Yang Jiazhen
Supervised by: Pan Buhan
