The planting time of the latest corn

To know the planting time of corn, we first need to understand the growth habits of corn. Corn has a short growth period and requires warm and rainy during the growth period. Corn consumes a lot of water, and if there is little precipitation and insufficient water for irrigation, the yield will be reduced or even the harvest will be eliminated. If the first autumn frost comes too early, the corn will freeze at maturity and yield will be reduced.

Corn planting time

Corn is divided into spring corn and autumn corn according to the planting time. Spring corn is sown in late April and early May and can be harvested in late August. Autumn corn should be sowed no later than mid-July and harvested in mid-late October. According to the morphological characteristics, growth characteristics and physiological characteristics, maize can be divided into several different growth stages, each stage includes different growth stages, these different stages and periods not only have their own characteristics, but also have a close relationship.

1. Seedling stage

Maize seedling stage refers to the period from sowing to jointing, which is a vegetative growth stage dominated by rooting and differentiation of stems and leaves. The growth characteristics of this stage are as follows: the root system develops rapidly, but the growth of aboveground stems and leaves is relatively slow. For this reason, the central task of field management is to promote root development and cultivate strong seedlings, so as to meet the requirements of "four seedlings" of early seedling, sufficient seedling, full seedling and strong seedling, so as to lay a good foundation for high yield of maize. This stage is divided into the following two periods.

① sowing time: seeds germinate and seedlings emerge through breaking the soil. At this time, we should pay attention to planting density, improve sowing quality, can not cover the soil, affect seedling emergence. 30-40% of nitrogen fertilizer and all phosphate and potassium fertilizer, zinc fertilizer and sulfur fertilizer can be applied appropriately in some areas. Spring drought is easy to occur in Heilongjiang area after seedling production is determined, which affects the emergence rate. Mild drought is beneficial to root development and downward banding, and watering is carried out when it is extremely dry. When a living seed is buried in the soil, when the external temperature is above 8 degrees, the water content is about 60% and the aeration condition is more suitable, the seedlings generally emerge after about 10 days. When the seed reaches the three-leaf stage, the nutrients stored in the seed are exhausted, which is called the "weaning period", which is the first stage of the maize seedling stage. At this stage, soil moisture is the main factor affecting seedling emergence. In addition, the sowing depth of seeds directly affects the speed of seedling emergence. The seedlings that emerge early are generally stronger than those who emerge later. According to the experiment, for every 2.5 cm increase in sowing depth, the emergence period is delayed by an average of one day, so the seedlings are weak.

② three-leaf stage: seedling emergence, three-leaf stage to jointing stage is the seed long root, differentiation of stems and leaves, stem and leaf growth is relatively slow, root system development is rapid. At this time, attention should be paid to promoting root growth and strengthening seedlings to ensure early emergence, high emergence rate and uniform emergence. The three-leaf stage is the first turning point in the life of corn, which changes from autotrophic life to heterotrophic life. From the three-leaf stage to the jointing stage, because the roots and leaves of the plant are underdeveloped, the nutrients absorbed and produced are limited, and the seedlings grow slowly, mainly for the growth of roots and leaves and the differentiation of stem nodes. Maize seedlings are afraid of waterlogging, not afraid of drought, waterlogging will affect the growth, serious will cause death of seedlings, mild drought is conducive to root development and rooting.

2. Jointing stage

60-70% of the total nitrogen fertilizer was used as topdressing, those with good growth were applied at one time in the big trumpet stage, and those with poor growth were applied twice at the jointing stage and the later stage. It is required to apply fertilizer depth 10cm and cover soil timely.

3. Loudspeaker stage

From the jointing stage, the trumpet mouth stage to the male stage, the stem internodes elongated rapidly, the leaves increased rapidly, the root system developed, and the female and male ears differentiated. At this time, attention should be paid to promoting leaves and strong culms to prevent lodging and increase panicle growth. The period from jointing to heading of corn is called panicle stage. Jointing is the second turning point in maize life. The growth and development of this stage is characterized by the simultaneous growth of vegetative growth and reproductive growth, that is, the exuberant growth of vegetative organs such as leaves and stem nodes and the strong differentiation and formation of reproductive organs such as female and male ears. This period is not only the most exuberant stage of growth and development of maize in its life, but also the most critical period of field management. For this reason, the central task of field management at this stage is to promote the high-yield appearance of the middle and upper leaves and stumpy stems, so as to achieve the goal of having more ears and larger ears. Use foliar fertilizer.

4. Heading stage

The period from heading to maturity of corn is called the heading period. When the male and loose powder of corn is drawn, all the leaves have been expanded and the plant has been fixed in length. The fertility characteristics of this stage: basically stop the growth of nutrients, and enter the stage of reproductive growth as the center, there is the third turning point in the life of corn. For this reason, the central task of field management at this stage is to protect leaves from damage and premature senescence, strive for more grains, grain weight, and achieve high yield.

5. Maturity

When maize enters the stage of flowering, pollination, fertilization and endosperm mother cell division, attention should be paid to protecting leaves and roots, preventing lodging, preventing senescence and increasing the number of seeds.