From seed germination to seed production, wheat goes through the growth and development process of germination, emergence, tillering, wintering, turning green, jointing, heading, flowering, filling and maturity.

After the spring, the wheat seedlings began to grow again and entered the green period. With the increase of temperature, the growth rate of wheat seedlings is accelerated, and the internodes of stems are gradually elongated from bottom to top, which is called jointing. At this time, you can feel the obvious protruding nodes by touching the straw near the ground with your hands. After jointing stage, the differentiated spike of wheat gradually grows upward with the elongation of internodes. When the young spike grows into the leaf sheath of the top leaf (flag leaf), the leaf sheath gradually unfolds into a spindle shape, which is called booting stage.

When the last internode of the wheat straw is elongated, the top of the wheat ear extends out of the flag leaf sheath, that is, heading. The heading date of wheat is generally from early April to early May. Flowering 2~6 days after heading. After flowering and fertilization, wheat entered the stage of grain filling maturity. Winter wheat is generally planted in the North China Plain, after 1 1 month, and then grows to about 10 cm. It will go through winter, during which it will not grow. In the next spring, after the temperature rises, it will turn green, and then it will start to grow and harvest after June 1 day every year. Winter wheat is usually harvested once a year.

Division of growth cycle of maize in different periods

From sowing to the maturity of new seeds, it is called the life of corn. It can complete its life cycle after several growth stages and growing periods. For corn buyers and large corn growers, it is very important to judge the growing period of corn not only by the number of days, but also by the number of leaves, so as to correct the error of the growing period days.

Reproductive stage

In the whole life process of maize, it can be divided into three different growth stages according to morphological characteristics, growth characteristics and physiological characteristics, and each stage includes different growth stages. These different stages and periods have their own characteristics and are closely related.

1. Seedling stage

Maize seedling stage refers to a period of time from sowing to jointing, which is a vegetative growth stage with rooting and stem-leaf differentiation. The growth characteristics of this stage are: the root system develops rapidly, but the shoot and leaves grow slowly. Therefore, the central task of field management is to promote root development, cultivate strong seedlings, achieve the requirements of "four seedlings" of early seedlings, whole seedlings, full seedlings and Miao Zhuang, and lay a good foundation for high yield of maize. This stage is divided into the following two periods.

A. sowing-three-leaf stage

When a live seed is buried in the soil, when the outside temperature is above 8 degrees, the water content is about 60%, and the ventilation conditions are suitable, it usually takes 48 hours, that is, it can emerge in 6 days. At the three-leaf stage, the nutrients stored in the seeds are exhausted, which is called "weaning stage", which is the first stage of maize seedling stage. At this stage, soil moisture is the main factor affecting seedling emergence, so watering soil moisture plays a decisive role in maize yield. In addition, the sowing depth of seeds directly affects the speed of emergence. Seedlings with early emergence are generally later than those in Miao Zhuang. According to experiments, every 2.5 cm increase in sowing depth delays the emergence time by one day on average, so the seedlings are weak.

B. Trifoliate stage-jointing stage

The three-leaf stage is the first turning point of maize life, and maize has changed from autotrophic life to heterotrophic life. From the three-leaf stage to the jointing stage, because the roots and leaves of plants are underdeveloped, the nutrients absorbed and produced are limited, and the growth of seedlings is slow, mainly manifested in the growth of roots and leaves and the differentiation of stem nodes.

Corn is afraid of waterlogging and drought at seedling stage. Mild waterlogging will affect growth, and severe waterlogging will cause dead seedlings. Mild drought will be beneficial to the development and rooting of roots.

2. Heading date

The period from jointing to heading of maize is called heading stage. Jointing is the second turning point of maize life. The growth and development characteristics of this stage are: vegetative growth and reproductive growth are carried out at the same time, that is, vegetative organs such as leaves and stems grow vigorously, and reproductive organs such as male and female spikes differentiate vigorously. This period is the most vigorous growth and development stage of maize in its life, and it is also the most critical period of field management. Therefore, the central task of field management at this stage is to promote the increase of middle and upper leaves and the appearance of stem fruits, so as to achieve the purpose of multi-spike and large-spike.

3. Flower-grain stage

The period from tasseling to maturity of maize is called flowering and fruiting period. When the corn is scattered, all the leaves have been unfolded and the length of the plant has been fixed. The reproductive characteristics of this stage: basically stop the growth of vegetative body, enter the stage centered on reproductive growth, and the third turning point of corn life appears. Therefore, the central task of field management at this stage is to protect leaves from damage and premature aging, strive for multiple heavy grains and achieve high yield.

(2) Growth period and growth period

1. The number of days from sowing to maturity in maize growth period is called growth period. The length of growth period is related to variety, sowing date and temperature. Generally, the growth period is short under the conditions of early-maturing varieties, late sowing and high temperature, and vice versa.

2. During the growing period of maize, due to the results of its own quantitative and qualitative changes and the influence of environmental changes, the external morphological characteristics and internal physiological characteristics have changed at different stages. These stages of change are called growth period, and the growth period and identification criteria are as follows:

(1) Emergence stage: the date when the seedling height is about 50px;

(2) Three-leaf stage: the third leaf of the plant is exposed from the center of the leaf for 75px；;

(3) jointing stage: the tassel of the plant is elongated, the total length of the stem node is 2 ~ 75px, and the leaf age index is about 30;

(4) trumpet stage: the female ear enters the jointing stage, the male ear enters the floret differentiation stage, and the leaf age index is about 46.

(5) Big trumpet stage: the female ear enters floret differentiation stage, the male ear enters tetrad stage, the leaf age index is about 60, the spikelet length in the middle and upper part of the main axis of the male ear is about 20px, and the three leaves of the stick are trumpet-shaped; (The big trumpet stage of maize is the stage where vegetative growth and reproductive growth go hand in hand. At this time, the 1 1 leaves of corn spread out, and the upper leaves protrude like big horns. At this time, the plant has formed about 60%, and the male panicle has begun to differentiate into small flowers, which is the key period for the formation of grains per panicle. At this time, if sufficient fertilizer and water are beneficial to increase the number of grains per ear, it is the key period of maize fertilization. Fertilization accounts for about 60% of the total fertilization, mainly nitrogen fertilizer, and it is also important to supplement a certain amount of potassium fertilizer. At this time, if the fertilizer supply is insufficient, it will inevitably lead to large plants, small ears and low yield. )

(6) tasseling stage: the tip of the plant tassel is exposed from the top leaf for 3 ~125px;

(7) Flowering period: the tassel of the plant begins to loose pollen;

(8) silking stage: the filaments of the female ear of the plant extend out of the bracts by about 50px.

(9) Grain formation stage: The grain volume in the middle ear of the plant is basically completed, and the endosperm is clear, which is also called the filling stage. During this period, some nitrogen fertilizer can be applied appropriately. Such as urea, can increase the yield, but remember not to apply nitrogen fertilizer before the silking stage, so as to avoid the failure of flowering and the phenomenon of no harvest.

(10) milk ripening stage: the dry weight of the middle ear grain in the plant increased rapidly and was basically completed, and the endosperm was milky white and then mushy;

(1 1) Wax ripening stage: the dry weight of the middle ear seeds in the plant is close to the maximum, and the endosperm is waxy, which can be cut off with nails. This period is the period with the highest yield and the best quality of high-grade super sweet corn, which generally lasts for about 2-3 days.

(12) Complete maturity stage: the seeds of the plant are dry and hard, and a black layer appears at the base of the seeds, and the latex line disappears, showing the inherent color of the variety. The general field or experimental field is marked by more than 50% of the plants in the whole field entering the growth period. Many farmers mistakenly think that the harvest yield is the highest in this period, because harvesting in this period will lead to a decline in yield, thick skin and slag, poor quality and so on.

Note: Leaf age index refers to the percentage of the number of leaves that have emerged in the total number of leaves in the main stem. For example, the total number of leaves in the main stem of the top super sweet corn is 18, and the leaf age index at jointing stage is about 30, that is, the number of leaves that have grown is about 6; The leaf age index of small trumpet stage is about 46, that is, the number of long leaves is about 8-10; And so on.