1. vegetative growth stage
From the sowing of Chinese cabbage to the formation of whole leaf bulbs, early-maturing varieties are generally less than 70 days, middle-maturing varieties are 75-85 days, and late-maturing varieties are more than 90 days.
(1) The germination period of Chinese cabbage is about 5-6 days, from the seed germination after sowing to the first true leaf sprouting. When Chinese cabbage seeds swell with water, the radicle extends out of the micropyle after 16h. After 24 hours, the seed coat cracked, cotyledons and hypocotyls were exposed, root hairs grew on the radicle, and then cotyledons and hypocotyls extended out of the ground, and the seed coat fell off. After sowing, the leaves of the third emperor unfolded, the leaves of the fifth emperor expanded, and at the same time, the first real leaf was exposed. The main root length can reach 1 1 ~ 15 cm, and there are 1 and 2 levels of lateral roots.
(2) At seedling stage, the first true leaf expanded to the 8th ~10 true leaf. At this time, there are 14 ~ 15 blades with blade length greater than 1cm, and about 5 ~ 6 blades with blade length less than 1cm. The growth period is about 16 ~ 18d. At seedling stage, the number of leaves differentiated quickly, the leaf area expanded and the root system developed slowly.
(3) The rosette period is about 23-28d from the end of seedling stage to the time when the outer leaves are fully unfolded and the heart Ye Gang begins to embrace, and the early-maturing varieties can be shortened by 6-8d. The leaf number of early-maturing varieties can reach 16 ~ 20, and the leaf number of middle-late-maturing varieties can reach 22 ~ 26. At this time, the 1 ~ 15 heart lobe of bulbous leaves has begun to differentiate and develop. At this stage, the taproot can reach more than 1m, the diameter of the root system can reach about 60cm, and the taproot group is distributed at a distance of 5 ~ 30cm from the ground.
(4) The fruiting period is about 40-60 days, and the early-maturing variety is 25-30 days. From the point of view of a single plant, at this time, the heart leaves begin to converge to the bulb and reach the harvesting state. Nodulation period can be divided into prophase, metaphase and anaphase. At the initial stage of nodulation, the lateral bulbous leaves grew rapidly and formed the outline of bulbous leaves rapidly. The distribution diameter of root system can reach 80 ~ 120 cm, and the main roots are distributed in the soil layer from the surface to 30cm. The middle stage of nodulation is the fastest growing period of bulbous leaves. At this stage, the leaves stop differentiating and the flower buds begin to differentiate. When the bulb expands to a certain size and its volume no longer increases, it enters the late fruiting stage. During this period, the bulb continues to enrich, but its growth slows down, its physiological activities weaken, and it gradually turns into dormancy preparation, and the root system begins to age.
(5) After harvesting in hibernation, Chinese cabbage will go into hibernation. During the dormancy period, the plants do not carry out photosynthesis, but only have weak respiration, but the nutrients in the outer leaves are still transported to the bulbous leaves, and the flower buds slowly differentiate at the reproductive tip. Storage period is related to variety characteristics, storage temperature and humidity.
2. Reproductive growth stage
(1) It takes about 8 ~ 12d from sowing to bolting in the spring of the following year during the greening period. At this stage, the leaves of seed plants gradually turn green, new roots begin to appear, and flower buds also increase obviously.
(2) The bolting period is about 15d from bolting to flowering. At this stage, the root system grows vertically downward; On the ground, flower buds formed.
(3) The flowering period is about 30 days from the beginning to the basic flowering. During this period, buds and lateral branches grew rapidly, and gradually entered the peak of flowering, and flowers kept sprouting. The more branches there are, the more fruits the seeds will bear. Seeds are collected from adult plants. Early-maturing varieties have 12 ~ 20 flower branches per plant, and mid-late-maturing varieties have 15 ~ 25 flower branches per plant. The number of flowers on the main branch and the first branch accounts for 90% of the whole plant, and the seed setting rate is also high.
(4) Pod-setting stage: The pod begins to grow after the flowers wither, and the pod-setting stage is the time when the seeds are fully developed. This period takes about 20 ~ 25d days. At this stage, the growth of flower branches basically stops, and the pods and seeds develop rapidly until the seeds mature, and the pods begin to turn yellow, and most of them can be harvested when they turn yellow and green.
The growth period of Chinese cabbage mentioned above is for the complete growth and development process. Chinese cabbage cultivated for some purposes (such as seed collection by small plants) does not necessarily need to go through all the growth stages.