On Bud withering and vernalization

Author: Nalan Rongxin

Up to now, the concept of "vernalization" or "vernalization" of cymbidium and Huilan is still vague and confused. the reason for this confusion is that the botanical word "vernalization" or "vernalization" borrowed from the orchid boundary is no longer the original definition of "vernalization" or "vernalization". However, it is extended to refer to the demand for a certain degree of low temperature in a certain period from spring and cymbidium bud formation to a certain period before flowers bloom, and it is a special sense of "vernalization" or "vernalization". This is the understanding or approval of most orchid friends on the vernalization or vernalization of Spring and Cymbidium-that is, if there is no certain degree of low temperature during a certain period from the formation of the bud of spring and cymbidium to before the flower blooms, the bud cannot open smoothly, normally and perfectly. On the other hand, Because the Lan people quoted the original definition of "vernalization" or "vernalization" in botanical sense when explaining what is "vernalization" or "vernalization", due to different understandings. Some orchid friends equate "vernalization" or "vernalization" with "vernalization" or "vernalization" in the botanical sense-this view often blames the failure of spring and cymbidium to "vernalization" or "vernalization". At the same time, because the orchid friends in the south successfully explored a set of practice of blooming spring and cymbidium without low temperature. Therefore, some orchid friends misread some means of promoting, protecting and excellent flowers except for low temperature conditions as "vernalization" or "vernalization". All these often make the new orchid friends at a loss what to do with the problem of "vernalization". In order to sort out these relationships. We must first clarify the definition of "vernalization" or "vernalization" in botany. The so-called "vernalization" or "vernalization" in botanical definition refers to the phenomenon that plants must meet certain low temperature conditions in order to urge plants to complete "flower induction", form "flower primordium", and then develop into complete flower organs. On the other hand, if there is no corresponding low temperature conditions, it will not form a flower bud at all. This is "vernalization" or "vernalization" in the botanical sense. The formation of spring and cymbidium buds does not need low temperature. On the contrary, it is in the summer when the temperature is very high. some Lanyou asked whether the winter temperature a few months before the bud formation would have an effect on flower bud differentiation. Although this doubt needs to be further verified, judging from the current situation, it can basically be eliminated. Because in winter temperature can not reach vernalization conditions in Guangzhou, Fujian, Hainan, Hong Kong, Taiwan, Hainan and other places, spring, cymbidium in the natural temperature conditions are not unable to form a bud, but after the bud will wither or the flower products are not good. From a botanical point of view, spring, Huilan (and spring sword, lotus petal orchid, etc.) are not "vernalization plants". The so-called "vernalization" of orchid is the thing after the formation of flower bud. The so-called "vernalization period" of spring and Cymbidium is more accurately a "dormancy period" or "hibernation period" in which physiological growth (vegetative growth) is inhibited in order to meet the needs of further reproductive growth after bud formation, and certain low temperature conditions precisely cater to this "dormancy period". But at the same time, This low temperature condition is not the only condition for the physiological growth (vegetative growth) of spring and Cymbidium to enter the "hibernating period" or "dormant period". Many years ago, Taiwan's Orchid Orchid was "forced" to enter the dormancy period of physiological growth by deducting water, reducing humidity and other measures under the temperature of 15 ~ 20 degrees. To sum up, the "vernalization" or "vernalization" often mentioned by the orchids is essentially different from the botanical definition of "vernalization" or "vernalization". It can only be said to be "quasi-vernalization" or "generalized vernalization". Strictly speaking, it is not very appropriate to borrow the word "vernalization" to express the demand for low temperature after spring and Huilan budding to a certain extent, so as to achieve a perfect opening performance in the coming year. However, since we have been talking about it for so many years, let's call it "quasi-vernalization" or "generalized vernalization". We know that vernalization (vernalization) in general refers to the induction and promotion of flower formation of overwintering plants by low temperature. In other words, plants cannot complete the initial differentiation of flower buds without going through this period of low temperature. in 1918, German botanist G. Gassner found that rye can be divided into winter and spring. Spring rye does not need to go through a low temperature period to heading, so it can be sown in spring. On the other hand, winter rye needs to go through a low temperature period of 1: 2 ℃ before and after germination, so it must be sown in autumn. Trofim, a Soviet agronomist in 1928. Lysenko found that winter varieties of cereal crops were in the tillering stage without jointing and flowering for a long time without low temperature. For example, the seeds of rye, wheat and barley can be jointed and blossomed after being naturally frozen in a snowy field for a period of time. If the newly germinated winter cereal seeds were frozen with 0-5 ℃ for a certain number of days before sowing, they could be jointed normally no matter when they were sown. He and his colleagues applied this cryogenic treatment to agricultural production and called it vernalization. In fact, the discovery of vernalization and the low-temperature treatment of sprouting seeds were not pioneered by the Soviets. In northern China, as early as the Qi Min Yao Shu written by Jia sixie in the Northern Wei Dynasty, there was the method of suppressing wheat (putting germinated winter wheat seeds in a pot at 0-5 degrees for 40-50 days and then spring sowing) has been widely used by the public, about 1400 years earlier than the Soviet Union. why is the vernalization of Cymbidium actually a kind of "quasi-vernalization" or "generalized vernalization"? This is because the flower bud of the so-called "vernalization period" of Cymbidium has grown, that is, the differentiation of flower buds has been completed, and what is needed is the preparatory period for the blooming of flowers with relatively low temperatures in a certain period of time. If there is no such low temperature preparation period, the flower stalk is often short and the flower posture is weak. As an ornamental plant, the opening quality of orchids is very important, so in order to enjoy the perfect opening, we must let spring and cymbidium have a full period of low temperature after budding. There is a need to distinguish between the spring and Cymbidium which have already flowered. If it does not go through a period of low temperature, it will only show the so-called "spring blooming" phenomenon, but there will be no rigid bud, dry bud or rotten bud. If there are rigid buds, dry buds and rotten buds, except that the vegetative growth can not be "braked" because the temperature is too high, and the remaining nutritional supply of orchid plants can not meet the needs of rapid growth of buds at high temperature, which leads to bud drying. Mostly because the bud suffered physical damage (such as bruise, burn, frostbite, suffocation, water and fertilizer injury, infection), and another important reason is that the vegetative growth of the orchid plant was relatively stagnant and then restarted unexpectedly. For plants to blossom and bear fruit, the first thing to complete is the transition from vegetative growth to reproductive growth. That is, after a certain period of vegetative growth, plants can feel external signals (low temperature and photoperiod) to produce flower stimuli. Floral stimuli are transported to the stem tip meristem, where a series of induction reactions take place, making the meristem enter a relatively stable state, namely floral decisive state (floraldeterminatedstate). Plants that enter the flower-forming state have the ability to differentiate flowers or inflorescences, that is, the so-called "flower induction". After the completion of flower induction, the stem growth cone of the plant showed morphological changes, and the meristem cells on the surface of the growth cone were rapidly divided so that the surface of the growth cone was wrinkled, and the flower primordium was formed in the place where the leaf primordium was formed. the primordium of each part of the flower is differentiated on the flower primordium. This process is floral organ formation. Floral organ formation also needs suitable internal and external conditions, including light, temperature, water, fertilizer and physiological conditions, and only in this way can the whole flowering process be completed. after the completion of the "flowering process" of Spring and Cymbidium, the "floral organ" will be exposed in the form of "bud" after further growth and development. at this time, the orchid plant has basically entered the reproductive growth stage. After entering the reproductive growth period, its vegetative growth will be in a relatively stagnant stage. So what is reproductive growth and physiological growth (vegetative growth)? to put it simply: the upper bud → flowering → seed is reproductive growth, tillering bud → leaves → grass is physiological growth. Orchid reproductive growth and physiological growth generally do not go hand in hand at the same time, but focus on. When the reproductive growth is in progress, the physiological growth will be inhibited; when the physiological growth is in progress, the reproductive growth will also be inhibited. This is a kind of "survival wisdom" gradually evolved in the game between orchid and nature for thousands of years based on the overall natural conditions and nutrient distribution. in practice, it is found that the early reproductive growth period of the orchid plant can be terminated, and if there are external factors that cause the orchid plant to suffer unexpected stimulation (such as abnormal temperature rise, excessive application of nitrogen fertilizer, drug stimulation and basin turning, etc.), the orchid plant will restart vegetative growth. This often leads to the interruption of its reproductive growth. In this case, even the formed bud will eventually wither due to the interruption of reproductive growth. another common situation is that when the bud gets up too early, because the external temperature is still relatively high, it is difficult to inhibit the physiological growth of bluegrass (that is, the vegetative growth mentioned above cannot be "braked"). This will also cause the interruption of its reproductive growth and eventually lead to "bud withering". However, the later reproductive growth of the orchid plant (such as the "shelling" of the core tip of the orchid, the "Pai Ling" period of the cymbidium) can not be terminated, no matter how bad the external environment is and how the orchid plant itself has few roots and leaves, as long as the orchid plant still has residual information, it will bloom to the end. in Jiangsu and Zhejiang Yilan tradition. If there are no special circumstances in the basin mouth that has already flowered after autumn, the basin will not be turned over. In the first fragrant Notes, Zhu Ke-rou once said: "when the cymbidium comes at the end of the spring orchid, don't plant it when you find it. You can't plant it until you hide the Qingming Festival, but you can't blossom early." The Quran people, for the strong and budding cymbidium which has never been "Pai Ling", it is also necessary to "bake it in the hoarding" rather than directly put it on the pot.