The growth process of oranges?

Citrus has a long vegetative growth period and no obvious dormancy process. In a year, with the change of four seasons, life activities such as root growth, germination, branch growth, flowering and fruit setting, fruit development, flower bud differentiation, defoliation dormancy and so on are carried out.

1, root growth period

The root system of citrus mainly has three growth peaks in a year, and the general situation in South China is as follows:

(1) The root system began to germinate before the spring shoot, and the root group began to grow actively after the spring shoot turned green, reaching the first growth peak before the Zhixia shoot.

(2) With a large number of summer buds sprouting, after the summer buds turned green and stopped growing, the root system appeared the second growth peak;

(3) The third growth peak appeared after the autumn shoots turned green and matured, with more hair roots.

The storage nutrition level of trees has great influence on root development. If the aboveground parts grow well, the trees are strong, the nutrition level is high and the roots grow well. On the contrary, if the above-ground part bears too much fruit, or the leaves are damaged, the tree is weak and the accumulation of organic nutrients is insufficient, then the root growth is inhibited. At this time, even if fertilization is strengthened, it is difficult to change the growth state of roots. Therefore, for trees with too many fruits, attention should be paid to thinning flowers and fruits, controlling overgrowth and useless branches, reducing nutrient consumption, protecting leaves, improving leaf functions, enhancing tree vigor, and promoting root growth.

2. New shoot growth period

After the leaf buds germinate, the cells of the apical meristem divide and the young branches begin to elongate. From the base up, the leaves of each node gradually spread out, new buds gradually formed, and then thickened. Shoot growth is usually divided into spring shoots, summer shoots and autumn shoots:

(1) The growth period of spring shoots is generally from February to April, that is, from around beginning of spring to before long summer;

(2) The growth period of summer shoots generally occurs in May-July before the long summer reaches the flood;

(3) The growth period of autumn shoots generally occurs from the end of July to 10, around the time when the first frost of trees comes;

The germination and growth of spring shoots mainly depend on the nutritional level of trees stored in the first year. When spring buds germinate, if there are many old leaves, the spring buds germinate neatly, with large growth and rich tissues; On the other hand, if there are too many fruits or fallen leaves in the previous year, there are few old leaves before the spring shoots germinate, and the storage nutrition of trees is insufficient, then the spring shoots occur less, the branches stop elongation soon, and the branches are short and thin.

3. Germination and flowering period

Citrus has a long flowering period, which can be divided into bud stage and flowering stage. Flowering period refers to the period when a few flowers bloom until all the flowers in the whole plant wither completely. Generally, it can be divided into early flowering period (5-25% of flowers are in bloom), full flowering period (25-75% of flowers are in bloom), late flowering period (more than 75% of flowers are in bloom) and final flowering period (all corollas are withered). Citrus usually blooms in spring.

(1) The budding stage is called budding stage. From the moment when citrus can recognize flower buds, the buds change from light green to before flowering.

(2) The flowering period begins when the petals are open and pistils and stamens can be seen, and ends when the flowers wither. In southern China, the flowering period is earlier and longer. Most varieties bloom from early March to mid-late April, and a few varieties bloom before March or after April.

The length of flowering period varies with species, varieties and climatic conditions. Flowering needs a lot of nutrients. If the tree has sufficient storage nutrients, developed flower organs, vigorous trees, neat flowers, long flowering period and high fruit setting rate. On the contrary, the quality of flowers is poor, the flowering period is short and the fruit setting rate is low.

4. Physiological fruit drop period

(1) The first physiological flowering and fruiting period usually occurs from the end of March to the end of April;

(2) The second physiological fruit dropping period occurred from late April to early June;

(3) Fruit dropping occurs late from July to before fruit ripening.

There are many reasons for falling fruit. In the early stage, it was mainly caused by underdeveloped flower organs, poor pollination and fertilization and poor external conditions. The main cause of fruit drop in the later stage is malnutrition. When nutrition is insufficient, the competition between new shoots and fruits for nutrients will often stop the development of embryos and cause fruit drop. Therefore, strengthening the nutritional management after flowering and controlling the vigorous growth of new shoots can often improve the fruit setting rate.

5, fruit growth and development period

The period from the beginning of fruit ovary expansion after flowering to fruit maturity is called fruit growth and development period. The growth of fruit usually presents an "S" or "double S" curve. According to the changes of cells, the fruit development process can be divided into cell division stage, cell expansion stage, cell expansion stage and maturity stage.

(1) cell division stage

Cell division is actually an increase in the number of nuclei. Mainly due to the repeated division of cells in pericarp and gizzard, the fruiting body is enlarged;

(2) fruit expansion period

After the first physiological fruit drop, cell division basically stopped, and the fruit turned to cell expansion. By the first half of June, the physiological fruit drop was over. From late July to early August, the fruit entered the second expansion peak. With the rapid increase of the sand sac, the fruit was basically shaped and the weight increased after entering the third expansion peak.

(3) Fruit maturity

The fruit tissue development is basically perfect, and the solids such as sugar, amino acids and protein increase rapidly, while the acid content decreases. Chlorophyll in pericarp gradually decomposed, carotene synthesis increased, and pericarp gradually colored. Fruit juice increases, pulp and fruit juice have color; The seed hardens and the fruit matures.

Extended content: habits and nutritional value of oranges.

Including China, there are 135 countries producing citrus in the world. Citrus likes warm and humid climate, and there is also a saying in China called "orange in the south and orange in the north". Citrus in China is mainly distributed in the south of the Yangtze River. There are 19 provinces producing citrus in China, among which the main producing areas are Zhejiang, Fujian, Hunan, Sichuan, Guangxi, Guangdong, Taiwan Province and other provinces.

The nutritional value of oranges;

1, oranges are rich in vitamin C and citric acid, the former has the function of beautifying, and the latter has the function of eliminating fatigue;

2. The thin skin inside the orange contains dietary fiber and pectin, which can promote laxation and lower cholesterol;

3. Hesperidin can strengthen the toughness of capillaries, lower blood pressure and dilate the coronary artery of the heart, so oranges are food to prevent coronary heart disease and arteriosclerosis. Studies have confirmed that eating oranges can reduce cholesterol deposited in arterial blood vessels and help reverse atherosclerosis;

4. In fresh citrus juice, there is a substance "Nomilin" with strong anticancer activity, which can decompose carcinogenic chemicals, inhibit and block the growth of cancer cells, multiply the activity of detoxification enzymes in human body, prevent carcinogens from damaging the nucleus and protect the integrity of genes.

References:

Analysis on Climatic Conditions of Citrus Growth in Bazhong Area-Anhui Agricultural Sciences 20 12 0 1

Climatic suitability analysis and regionalization of citrus planting in quanzhou county, Guangxi

Introduction to Distribution and Growth Environment of Main Citrus Producing Areas _ Fruit Tree Planting Network

Growth Cycle of Oranges | Maintenance of Flowers and Trees | China Nursery Net