What is the growth process of soybean? The latest full analysis
Soybean is one of China's important food crops. It is an annual herbaceous plant of the genus Glycine in the legume family. It is cultivated in all parts of China and is also widely cultivated around the world. Its life cycle goes through six growth stages: seed germination and emergence, seedling growth, flower bud differentiation, flowering and pod setting, seed filling, and maturity. Let's take a look at the growth process of soybean together below!
Emergence stage
The radicle of the soybean seed first protrudes from the micropyle of the ovule. When the radicle elongates to the same length as the seed, it is called germination. The hypocotyl elongates, the seed coat falls off, and the cotyledons emerge above the soil surface as the hypocotyl elongates. When the cotyledons unfold, it is called emergence. Under suitable conditions, emergence can occur 4 to 6 days after sowing. When more than half of the cotyledons in the field have emerged from the soil, it is the emergence stage.
Seedling stage
From emergence to the beginning of flower bud differentiation is the seedling stage of soybean. After emergence, the 2 cotyledons unfold, and the young stem continues to elongate. The 2 opposite simple leaves above then unfold; this is called the simple leaf stage. As the young stem keeps elongating, when the first compound leaf grows, it is called the 3-leaf stage. At the 3-leaf stage, the aboveground part grows relatively slowly, while the underground root system grows relatively quickly and forms root nodules. By the end of this stage, the root system has initially formed and begins to require more water and nutrients. The seedling stage lasts about 20 to 25 days, accounting for 1/5 of the entire growth period. This period is the root-growing period, and attention should be paid to seedling hardening and strengthened field management to achieve full, uniform, and strong seedlings, laying the foundation for high yield.
Flower bud differentiation stage
From the beginning of flower bud differentiation to the first flowering is the flower bud differentiation stage of soybean, generally about 25 to 30 days. When 4 to 5 compound leaves appear, branching begins at the lower part of the main stem, and flower buds differentiate at the same time. The process of flower bud differentiation begins with the appearance of a hemispherical flower bud primordium, followed by the formation of bracts in front of it, then the formation of the calyx tube, and then the differentiation of the keel petal, wing petal, and standard petal. The ring-shaped stamen primordium differentiates in succession, and in the center of the stamens the pistil begins to differentiate, with ovule primordia appearing. Subsequently, the ovules and anther primordia differentiate, the floral organs gradually enlarge, and finally flower buds, pollen, and embryo sacs form one after another, completing flower bud differentiation. During the flower bud differentiation stage, the plant enters a period in which reproductive growth and vegetative growth proceed together. At this time, fertilizer and water management must be strengthened, while attention must be paid to coordinating vegetative growth and reproductive growth to meet the requirements of strong plants, many branches, many flower buds, and healthy flowers.
⟦NL>Flowering and pod setting stage
From the first flower to the last flower is the flowering stage of soybean. The flowers are very small and are borne in leaf axils or at the top of the stem. The number of flowers borne on each flower cluster varies depending on the variety and cultivation conditions. The rate of flower and pod drop is high, so the number of pods set per flower cluster is relatively small. Soybean flowering occurs mostly from 6 to 9 in the morning, and it generally takes 3 to 7 days from budding to flowering. After the ovule is fertilized, the ovary gradually expands to form a soft, small green young pod. When the pod length reaches 1 cm, it is called pod setting. The growth of the pod is first an increase in length, then an increase in width, and finally an increase in thickness. The flowering and pod setting stage is the period of most vigorous growth for soybean and the period when it needs the most water and nutrients, while also requiring sufficient light. On the basis of full seedlings, strong seedlings, and many branches in the earlier stage, fertilizer and water management should be strengthened during the flowering period, and good aeration should be maintained, so as to achieve many flowers, many pods, and many seeds and to reduce flower and pod drop.
Seed filling stage
From the time the seeds in the pod begin to expand until they reach their maximum volume and weight is the seed filling stage of soybean. Within 10 days after flowering, the accumulation of dry matter in the seeds increases slowly, and then increases very rapidly over the following 7 days. Most of the dry matter is accumulated over about 21 days after that. The seed filling stage lasts about 30 to 40 days. When seed filling is completed, the seed moisture content is about 90%. The seed filling stage is an important period for soybean seed formation. Whether soybean growth is normal at this time will determine the number of seeds per pod, the seed weight, and the chemical composition of the seeds. At this time, drought or excessive rain causing waterlogging can cause dead pods, shriveled seeds, and reduced seed weight, seriously affecting yield. Ensuring normal seed development requires meeting two conditions: the plant itself has abundant stored materials, the root system does not senesce, and the assimilation of the leaves is vigorous; and there must be an adequate water supply.
Maturity stage
The soybean leaves turn yellow and drop, the seeds dehydrate, and the variety's inherent characteristics appear. At this time, the seed moisture content has dropped below 15%, until when the plant is shaken there is a slight rattling sound inside the pods; this is the maturity stage. At this time, soil moisture should be reduced to accelerate the drying of seeds and plants, facilitating timely harvest, while preventing excessive fertilizer and water from causing delayed senescence, which would affect timely harvest and crop rotation. In this stage, clear and dry weather can promote maturity and help improve quality.