When is the planting time for corn?
To know the planting time for corn, we first need to understand its growth habits. Corn has a relatively short growing period, and during that period it requires warmth and plenty of rain. Corn consumes a large amount of water; if rainfall is low and irrigation water is insufficient, yields will drop or the crop may even fail completely. If the first autumn frost arrives too early, the corn will be frozen during the ripening stage, which will also reduce the yield.
Corn planting time
Depending on the planting time, corn is divided into spring corn and autumn corn. Spring corn is sown in late April to early May and can be harvested in late August. Autumn corn must be sown no later than mid-July and is harvested in mid-to-late October. Over the course of its life, corn can be divided into several different growth stages according to morphological characteristics, developmental features and physiological traits. Each stage includes different growth periods, and these different stages and periods each have their own characteristics while also being closely connected.
1. Seedling stage
The corn seedling stage refers to the period from sowing to jointing, a vegetative growth stage dominated by root formation and the differentiation of stems and leaves. The growth characteristics of this stage are: the root system develops rapidly, but the growth of above-ground stems and leaves is relatively slow. For this reason, the central task of field management is to promote root development and cultivate strong seedlings, achieving the "four seedling" requirements of early seedlings, sufficient seedlings, uniform seedlings and strong seedlings, so as to lay a solid foundation for a high corn yield. This stage is further divided into the following two periods.
① Sowing period: the seed germinates and breaks through the soil to emerge. At this time, pay attention to planting density and improve sowing quality; do not cover with too much soil, as this affects emergence. 30-40% of the nitrogen fertilizer and all of the phosphorus and potassium fertilizer, and in some areas an appropriate amount of zinc fertilizer and sulfur fertilizer may be applied. After thinning to a stand, cultivate the field; the Heilongjiang region is prone to spring drought, which affects the emergence rate. Mild drought is beneficial to root development and downward growth; irrigate during extreme drought. When a living seed is buried in the soil and the outside temperature is above 8 degrees, the moisture content is about 60% and the aeration conditions are relatively suitable, it generally emerges after about 10 days. When it grows to the three-leaf stage, the nutrients stored in the seed are exhausted, which is called the "weaning stage"; this is the first phase of the corn seedling stage. At this stage, soil moisture is the main factor affecting emergence. In addition, the sowing depth of the seed directly affects how quickly it emerges; seedlings that emerge early are generally more robust than those that emerge late. According to experiments, for every 2.5 cm increase in sowing depth, the emergence period is delayed by an average of one day, so the seedlings are weaker.
② Three-leaf stage: from emergence and the three-leaf stage until the jointing stage, the seed grows roots and differentiates stems and leaves; stem and leaf growth is relatively slow while the root system develops rapidly. At this time, pay attention to promoting root growth and strong seedlings, and ensure early emergence, a high emergence rate and uniform emergence. The three-leaf stage is the first turning point in the life of corn; corn shifts from autotrophic life to heterotrophic life. From the three-leaf stage to jointing, because the plant's root system and leaves are not well developed, the nutrients absorbed and produced are limited, and the seedlings grow slowly, mainly carrying out the growth of roots and leaves and the differentiation of stem nodes. During the seedling stage, corn fears waterlogging but not drought; waterlogging can affect growth in mild cases and cause seedling death in severe cases, while mild drought is beneficial to root development and downward growth.
2. Jointing stage
Apply 60-70% of the total nitrogen fertilizer as a top dressing. For crops growing well, apply it all at once at the large trumpet stage; for crops growing poorly, apply it in two split applications at the jointing stage and the late large trumpet stage. The fertilization depth should be 10 cm, and soil should be covered promptly.
3. Large trumpet stage
From the jointing stage and the large trumpet stage until the tasseling stage, the internodes elongate rapidly, the leaves expand quickly, the root system develops, and the female and male ears differentiate. At this time, pay attention to promoting leaves and strengthening stalks, preventing lodging, and increasing ear growth. The period from jointing to tasseling in corn is called the ear stage. Jointing is the second turning point in the life of corn. The growth and development characteristics of this stage are: vegetative growth and reproductive growth proceed simultaneously, that is, the vigorous growth of vegetative organs such as leaves and stem nodes and the intense differentiation and formation of reproductive organs such as the female and male ears. This period is the most vigorous stage of growth and development in the life of corn, and also the most critical period for field management. For this reason, the central task of field management at this stage is to promote the enlargement of the middle and upper leaves and a sturdy, compact stalk form for high yield, so as to achieve the goal of more ears and larger ears. Use foliar fertilizer.
4. Tasseling stage
The period from tasseling to maturity in corn is called the tasseling stage. When corn tassels and sheds pollen, all the leaves have already unfolded and the plant has reached its final height. The growth characteristics of this stage are: the growth of the vegetative body basically stops, and the plant enters a stage centered on reproductive growth, marking the third turning point in the life of corn. For this reason, the central task of field management at this stage is to protect the leaves from damage and premature aging, and to strive for more kernels and greater kernel weight, so as to achieve a high yield.
5. Maturity stage
Corn enters the stage of flowering, pollination, fertilization and endosperm mother cell division. At this time, pay attention to protecting the leaves and roots, preventing lodging and aging, and increasing the number and weight of kernels.
Precautions for corn planting
Corn is a light-loving crop that both needs water and fears waterlogging. Its water requirements differ at different growth stages, and it requires fertile soil that can be both irrigated and drained. Therefore, when preparing the land, three ditches should be opened well, namely the main ditch, the surrounding ditch and the bed ditch, and every ditch should be connected so that no water accumulates in them and irrigation and drainage are both possible. For land preparation for corn, it is best to plow the soil in alternate years to freeze the clods, or to plant a season of winter vegetables, so that when corn is sown the following year, the soil is loose and dry with good aggregate structure, which is beneficial to corn growth. If the land has not been plowed in alternate years, then after the beginning of spring, choose a sunny day to prepare the land promptly, and keep the soil dry and refreshing to prevent clodding and block formation that would affect root growth; at the same time, do a good job of removing weeds.