Orchid leaves are a little twisted, and the back of the leaves is a little white. What should I do?

Chinese cymbidium, also known as cymbidium, is one of the orchids that many flower lovers like. Compared with Cymbidium hybridum, Cymbidium hybridum and other varieties, Cymbidium hybridum leaves are often wider and longer, and the leaves are dark green, so the whole plant looks stronger. Of all the orchids, I like raising China orchids best. On the one hand, Chinese cymbidium blooms easily, and flowers can be seen almost every year. On the other hand, the leaves of Chinese cymbidium are broad and shiny, and when they don't bloom, the leaves are also very ornamental. However, when some flower friends raise orchids, they find that the leaves will become distorted and uneven, which will affect the ornamental value. Why are the leaves of Chinese cymbidium twisted? Apart from the fact that individual varieties are easily distorted, let me talk about my opinion.

Harm of abnormal distortion of cymbidium leaves

1. When the ornamental leaves of Cymbidium hybridum are twisted, the biggest harm is to affect the ornamental, making the leaves look irregular, which will greatly reduce the ornamental value of the whole plant.

2, easy to get sunburned, when the leaves of cymbidium are twisted, it will also affect the growth. The reason is that the positive and negative structures of Cymbidium hybridum leaves are different, so the light resistance is different. Generally speaking, the light resistance of the front of Cymbidium hybridum leaves is much better than that of the back, and it is not easy to get sunburned. When cymbidium leaves are twisted, the back of the leaves with poor light resistance grows on them, and it is easy to get sunburned when exposed to strong light.

3. It affects the respiration of leaves. In addition, the stomata of Cymbidium hybridum are mainly distributed on the back of leaves. When the leaves are twisted, the back turns to the top. When the light is strong, the stomata will be completely closed, which will affect the evaporation and absorption of water, thus affecting the growth of the whole plant. In addition, the back of cymbidium leaves turns to the top, which is easy to accumulate dust and block pores, affecting the breathing of leaves.

Deformation principle of cymbidium leaves

The reason why the leaves of cymbidium sinense are twisted is that the cell division speed in a certain position is different during the growth process. In some places, cells divide quickly, and in some places, the position where cells divide quickly will gradually roll back, and the position where cells divide slowly will roll down (as shown in the following figure 1), so the leaf surface will become uneven. On the same Chinese cymbidium leaf, the greater the gap between the place where cells divide quickly and the place where cells divide slowly, the more serious the leaf distortion is.

Fig. 1: schematic diagram of Moran twisted blade

If you don't understand what I mean by "the speed of cell division", you can think of climbing the morning glory and beans. Plants such as morning glory and beans can attach themselves to other things because their vines divide at different speeds. Often on the same vine level, the outer cells facing the light divide quickly, while the inner cells facing the backlight divide slowly, so they look like they have legs and climb up step by step, fully accepting the light and rain, so as to make themselves grow healthily (figure below 1). The twisted leaves of Chinese cymbidium are the same as those of morning glory and bean vine, but the twisted leaves of Chinese cymbidium are wider and the degree of distortion is not as serious as that of cylindrical morning glory and bean vine.

Figure 1: schematic cross-sectional view of morning glory vine

Main causes of deformation of cymbidium sinense leaves

1. Hormones cause leaf deformation. In order to make Cymbidium hybridum grow better, its leaves are more shiny, dark green and shiny, some people spray some hormone drugs on Cymbidium hybridum, such as indolebutyric acid (IBA), naphthylacetic acid (NAA) and gibberellin. When spraying these hormone drugs, due to uneven spraying, the cell division speed on the leaves of cymbidium sinense is different, which leads to the phenomenon that the leaves are twisted and uneven.

2. Too strong or uneven illumination will cause the leaves to twist. Plants are phototropic, and orchids are no exception. When the leaves are exposed to uneven illumination for a long time (excessive illumination), the cell division speed of the same leaf on the illumination side is faster than that on the backlight side, resulting in leaf deformation. The wider the leaves of Chinese cymbidium, the easier it is for them to be distorted due to uneven illumination. This is exactly the same as climbing vines, morning glory and beans. Where there is light, there is light. It is not that its vines have eyes and are changing the direction of climbing, but that the position of cell division speed on the vines is changing with the change of light.

3. Excessive fertilization leads to leaf distortion.

In the process of maintenance, excessive fertilization will also lead to leaf distortion. In domestic flowers, it is common that leaves are twisted due to excessive fertilization. This situation is often more prominent in the new leaves, and the old leaves are fine. Because plants give priority to delivering nutrients to new leaves and then to old leaves.

When fertilization is excessive, the leaves of cymbidium sinense and other flowers are distorted. The main reason is that there are too many nutrients, and the nutrients delivered by roots to leaf cells are unbalanced, which leads to the disorder of cell division speed and the distortion of leaves. The more severe the leaf distortion, the more serious the fat damage. Sometimes when too much fertilizer is applied to Cymbidium hybridum, not only the leaves will be twisted, but also the burnt tips, yellow leaves and rotten roots will be directly caused.