Although April is the return of spring, the season of all things flourish, people should feel happy fishes. But along with warmer temperatures, people will encounter a trouble their minds, and that is flying catkins.
Indeed, each year 4 - In May, the city most of central and northern regions, will be more or less subject to influence Fei Xu. Especially in Beijing and April, it seems completely like small balls of cotton candy, big like clouds Fei Xu occupied. If twelve looks pretty crystal white, quite interesting, and when they are flying up in droves when it is simply a disaster - people's nostrils and mouth become the main target of their attacks, little attention this round will inhale "cotton," it was coughing, and even lead to the risk of allergies. So people had to come before winter should wear masks to prevent these attacks Fei Xu.
So, these Fei Xu is backing it? Perhaps many people will say: This is not simple, this is a willow catkins produced chant! In fact, so to speak, it is to make willow back suckers. In fact, not only can produce willow catkins, poplar can. In most parts of northern China, such as Beijing, the willow only "minority", is the main production poplar floc, and only to the more humid southern region, willow will become the majority.
Although the beauty of the sky Fei Xu, after all, but to a lot of people's lives affected. So why should produce poplar willow catkins? How do we reduce catkins produce it?
Willow present a
Willow can produce floc, which reflects the close relationship they have - from botanically speaking, are members of the Willow "Salicaceae" under. But be careful points, both can still rely on a number of different features were divided into Populus and Salix. To distinguish willow, watching their blades most easily: Poplar Leaves usually large, oval or elliptical form, while the leaf willow is more slender, usually long and narrow. Also from their winter buds can also be distinguished from each other: a large poplar buds, wrap multiple gold scales, and Salix buds small, scales only one exists.
Poplar and willow trees are very common in the city, and as much again in Poplar most northern region. According to statistics, in Beijing, nearly 200 million trees and landscape trees, poplars and willows total accounted for about 70%, which shows the total yield floc these willows are considerable. Beijing is the main planting willow trees tomentosa (Populus tomentosa), Populus (P. canadensis) and Salix (Salix matsudana), while the proportion of over 60% poplar. And, in particular, poplar trees as Populus tomentosa more dense planting in urban areas, so that the source of the northern city of Fei Xu, mainly poplars.
In all fairness, in addition to over Piaoxu this thing really be regarded as poplar is a good street trees and park trees. why? First, the long fast. Poplar is a fast-growing species, a twelve meter high poplar trees, only two or three years will be able to grow to nearly ten meters high, put up a shade up. Second, a good feed. Poplar roots deep and developed, especially for arid tomentosa that originated in northern species, a little more responsive to the drying of the water environment. Third, the tree good. Yang Shuguan lush, tall and straight trunk, for tomentosa, the young shoots after falling in the branches left out one "eye", but also added a lot of fun. Unfortunately, so many excellent characteristics, so that "production Xu" This one disadvantage bad gruel.
Why willow production Xu?
In fact, if you look closely, not each of them will yield poplar floc. But those who do not produce floc poplar, in fact, is Piaoxu made a "contribution." why? Originally, Poplar is dioecious plants. Those poplars not produce floc, are male trees. Each year in late winter, we can see some poplar branches hanging his head there is a likeness taupe article "Caterpillar" stuff, that is, the male trees grow inflorescence. These inflorescences produce countless tiny pollen floating around the wind - these pollen, and sometimes also some late winter pollen allergy culprit. Meanwhile, female poplar trees also grow a green strip of female inflorescences, each of the above flower petals are lost, leaving only two large and sticky stigma, waiting for a "trapping" air the floating pollen. Accept the pollen of female flowers, they follow up, develop into fruit, fruit breeds within a few dark brown seeds.
For all plants, how to spread the seeds of the population is a big decision of life and death. The farther the distance traveled, it can occupy "territory," the greater, the more likely to survive. For poplar, its seeds attached to the base of a large group of lint, these light and fluffy fluff, so that the seeds can drift with the wind, it will not sink to the bottom after falling into the water, but with water rafting. The so-called "willow catkins Suifeng Wu, Yang Hua light by water," Yang Xu catkins is described with the wind and currents spread the scene.
As relatives of poplar, willow and poplar produce flocculation process is similar. But in the pollination process, willow able to rely on it has nectaries attract insects to assist in pollination, not exactly need the help of the wind help. This pollen allergy, it may be good news!
Fei Xu how to govern?
Fei Xu although the United States, but that is a hassle. Beyond giving people the sensory discomfort, but also pose a safety hazard: the sky flying catkins easily obscured the driver line of sight, easy to plug the ventilation pipes, filtration equipment and some mechanical equipment, Fei Xu Furthermore, since highly flammable, if the experience gathered more cigarette butts and other fire source, but also easy to cause a fire. Therefore, a lot of people come up with ways to try to solve this problem. This method can be summed up, it can be roughly divided into "drug", "transgender" and "Substitution."
The so-called "drug", is to use special plant growth regulator applied to the female tree, suppress it to fruition. The results show, poplar and willow differentiation, rely mainly on the ratio of cytokinin and gibberellin body between the two can be adjusted. When the high proportion of this time, help produce flower buds, anyway, it is to produce buds. Therefore, researchers through growth regulators containing gibberellin injection into the trees, and to reduce the cytokinin / GA ratio, in order to inhibit the differentiation of flower buds. At present, such as "One flower suppression" of drugs have been widely used in urban willow anti floc work. However, this approach requires each year to a female tree, the medicine, the more labor costs consume enormous.
Branches "denatured" sucked amputation female tree grafted on male tree branches, so that the growth of the new branches will not open female flower, of course, will no longer produce a floc. But the same, the same way this time-consuming, and just seem grafted trees bare of trees and landscape features had a significant impact.
Of course, the most thorough way is to replace all male female tree tree. Obviously, however, this "Substitution" means though drastic, but to remove the tree has been grown for many years, successive batches will still need to have reached the age of trees grown replaced with a new male trees. It takes years to achieve the purpose of consuming, it is a long and systematic project. So, faced with Fei Xu, to take the above three ways, according to local conditions of comprehensive management. And it can be expected that the annual "April Fei Xu," the landscape will still exist for quite some time.
The entire contents of a user on Baidu know daily newspaper published a third party is strictly prohibited reproduced. Any third party to use the content, you must contact Baidu know daily zhidaoribao@baidu.com, obtain written authorization to use the content and in the manner prescribed.
Article Source: Baidu know daily (http://zhidao.baidu.com/daily)
Original link: http: //zhidao.baidu.com/daily/view id = 4247?