The Transport Direction of photosynthate in different growth and Development stages of Cymbidium

This is actually a problem of the change of the relationship between "sink" and "source". In different stages of growth and development, the growth center is different.

1. Leaf bud growth period: during this period, young leaf buds are the first growth center. Its own photoassimilation products not only do not move out, but also strongly attract photoassimilates from other leaves to transport to it. Some of the assimilates of adult leaves were also transported to the root, mainly concentrated in the root tip.

2. Vegetative growth period: both the root and the first leaf of the year are metabolic centers, and the former is slightly stronger than the latter. This time is mainly the storage stage of assimilates to prepare for reproductive growth.

3. Flower bud growth period: the photoassimilates of each leaf are only transported to the flower bud, indicating that there is only one growth center in the reproductive organs during this period.

4. Capsule growth: at this stage, leaf assimilates are mainly transported to the capsule, but some are also transported to the root. Assimilates transported to roots and pseudocorms are mainly stored in the form of starch grains. (Ye Qingsheng, Pan Ruichi)