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.
First, 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 the soles of the feet plays a decisive role in corn 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, trilobal 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.
Extended data
During the life of maize, due to the results of its own quantitative and qualitative changes and the influence of environmental changes, both external morphological characteristics and internal physiological characteristics have changed at different stages. The changes in these stages are called growth period, and the growth period and identification criteria are as follows.
(1) Emergence stage: the date when the seedling is about 2cm high.
(2) Three-leaf stage: the third leaf of the plant is 2-3cm away from the leaf center.
(3) jointing stage: the tassel of the plant is elongated, the total length of the stem node is 2-3cm, 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 the floret differentiation stage, the male ear enters the tetrad stage, the leaf age index is about 60, the spikelet in the middle and upper part of the main axis of the male ear is about 0.8cm long, and the three leaves of the stick are trumpet-shaped.
(6) tasseling stage: the tip of the plant tassel is exposed from the top leaf for 3-5 cm.
(7) Flowering period: the tassel of the plant begins to loose pollen.
(8) silking stage: the filaments of the female ear of the plant protrude from the bracts by about 2 cm.
(9) Grain formation stage: the grain volume in the middle ear of the plant is basically built, and the endosperm is clear, which is also called filling stage.
(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.
(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.
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