The Boundless Sea of Orchids: The Vast and Limitless World of Orchids

The Cymbidium plant is mainly composed of leaves (leaf), pseudobulbs (pseudobulb), sheath leaves (sheath leaf) and thick fleshy roots (root). Both the leaves and sheath leaves have latent buds at their junctions with the pseudobulb. The sprouting of these latent buds is controlled by apical dominance (Apical dominance). Latent buds above the swollen part of the pseudobulb are less likely to sprout, while latent buds below the swollen part of the pseudobulb are more likely to sprout. Latent buds can sprout into vegetative buds or reproductive buds, and this is greatly influenced by light intensity and bud position. When light is insufficient, the production of photosynthetic products decreases, reducing the carbon/nitrogen ratio in the plant body, which easily leads to shrunken pseudobulbs and failure of flower bud formation. Usually, latent buds located at lower nodes (lower node) are more likely to sprout into vegetative buds, while latent buds located at upper nodes (upper node) on the pseudobulb often develop into flower buds to form inflorescences. If a latent bud differentiates into a vegetative bud (leaf bud), it then unfolds leaves, and after the leaves have fully expanded, it begins to accumulate nutrients, causing the pseudobulb at the base of the bud to begin rapidly swelling to form a second-generation pseudobulb. Therefore, several plants are often seen connected together. Chunlan (Cymbidium goeringii) after the pseudobulb becomes plump, if nutrient supply remains sufficient and it encounters appropriate low-temperature stimulation, the latent bud can smoothly differentiate into a flower bud and can successfully send up a scape and bloom in winter and spring. The entire growth cycle, from latent bud sprouting and growing into leaves, flower bud differentiation and completion of blooming, to the next year's vegetative bud sprouting again, takes about one year. In addition to the above factors such as bud position and apical dominance that affect the sprouting of pseudobulbs in Chinese cymbidiums, how to promote rapid pseudobulb swelling to achieve the goal of rapid propagation is the key concern of orchid growers. The following introduces factors such as light intensity, temperature, nutritional requirements and cultivation media: (1) Light Chinese cymbidiums belong to shade-loving plants with relatively low light requirements. Generally, shade nets combined with simple facilities are often used for cultivation, but under excessive shading, although the leaves are longer, the dry matter weight decreases, causing the pseudobulbs to be shrunken and poorly developed, and even causing failure to bloom. The ideal shading level is about 50~75% of full sunlight, with an average light intensity of about 10000~20000lux being appropriate. (2) Temperature Temperature has a very important influence on the sprouting rate of latent buds on Chinese cymbidium pseudobulbs, leaf differentiation and growth, and flower bud differentiation and blooming. Low day/night temperatures (20/15°C) are most favorable for leaf differentiation and pseudobulb development, but are poorer for latent bud sprouting. To promote faster latent bud sprouting and rapid leaf elongation, high day/night temperatures (25~30/20~25°C) are preferable, while for scape emergence and later flower bud development, 25/20°C is best. Too low and flower buds cannot form, too high and deformed flowers are easily produced. After flower bud differentiation, if continuous high temperatures (〉30°C) occur, the flower bud cannot send up a scape and elongate; it needs cool temperatures of 20/15°C for the flower bud to elongate rapidly. (3) Nutritional requirements For Cymbidium plants, among the elements, nitrogen fertilizer has the greatest influence on their growth. Although the demand for phosphorus and potassium fertilizers is not as high as for nitrogen fertilizer, they play important roles in pseudobulb plumpness and blooming, so neither can be neglected when fertilizing, and attention must be paid to supplementing trace elements. In addition, there is an interaction between fertilizer amount and light intensity. Under a cultivation environment of 10000~20000lux, the effect of fertilization is not significant, but under lower light intensity (below 10000lux), fertilization can compensate for the influence of low-light stress on vegetative growth. At present, many fertilizer products are available on the market. Judging from the effect of fertilization, chemically quick-acting liquid fertilizers can be quickly absorbed by plants after application and are the fastest-acting topdressing. Slow-release granular chemical fertilizers have a fertilizer effect lasting 1~2 months, are convenient to use and save labor, but the imported unit price is relatively high, and cultivation costs will increase slightly. In recent years, various organic granular fertilizers have also become available for selection. When using them, two points should be noted: 1. Fertilizer must be fully fermented to avoid damaging orchid plants due to heat generated by fermentation after application. 2. Some organic fertilizer products are combined with microbial fertilizers, and after application will produce mycelium. It is advisable to observe their reaction when growing together with orchid plants before deciding whether to apply them on a large scale.