Peanut is an annual herbaceous plant in the family of Leguminosae. From the germination of the seeds to the maturity of the pods roughly through the following seven stages: (a) seed germination and seedling peanut seed shape, color, size, etc. is an important basis for identifying varieties. Peanut seeds are composed of two parts: the seed coat and the embryo. The seed coat mainly plays a protective role. The embryo consists of four parts: germ, embryonic axis, radicle and cotyledons. The germ is located between the two cotyledons and consists of the main bud and lateral buds. The main bud later develops into the main stem, and the lateral buds develop into the first pair of lateral branches. At the lower end of the germ is a stout embryonic axis and a prominent radicle. Inside the mature seed, the main stem has two young compound leaves, within which there are still 3-4 small compound leaves or leaf primordia; the lateral buds can be seen on the two bracts or l bracts and l true leaves, within which there are also 2-3 leaf primordia, and in the axils of the bracts there are already l one or two secondary buds primordia. So the peanut seed is actually a fairly fully differentiated young plant. Peanut seed maturity, given the most suitable germination conditions can not be normal germination, this characteristic is called dormancy. The time required for seed dormancy is called the dormancy period (from the time the peanut is ripe and harvested until it is ready to germinate). Different varieties of seeds, the length of the dormancy period varies greatly, the general pearl bean type and multi-grain varieties of short dormancy period, in the seed before harvest, such as high soil moisture, higher temperatures, some will be able to germinate in the soil; and common type and Longsheng type varieties, the dormancy period is longer. Before sowing with shell sunshine, seed heating treatment and use of vinyl to break seed dormancy, to accelerate the enzyme activity, early seed germination has a better effect. Seed germination and seedling emergence process: fully developed seeds, after completing a certain period of dormancy, in the appropriate conditions, can germinate seedlings. When germinating, the embryonic root first breaks through the seed coat to the underground rapid growth, long to l cm or so, the embryonic axis quickly differentiated to the ground extension, the cotyledons and embryonic axis pushed to the surface. When the top of the cotyledon breaks through the surface of the soil to see the light, the embryonic axis is to stop elongation, and the germ rapid growth of the first true leaves unfolding for the emergence of the seedling. Spring peanut from seed germination to seedling, early maturing varieties need about 10-15 days; medium maturing varieties need about 15-20 days. Peanut seed germination requires higher temperatures. Pearl bean type and multi-grain type early peanut, seed germination minimum temperature of 12 ℃, ordinary peanut minimum temperature of 15 ℃. The optimal temperature for germination, early small peanuts about 23 ℃, large peanuts 26-30 ℃. Temperature is too low seed can not germinate, often caused by rotten seeds; temperature is too high (40 ℃ or more), the embryonic root development is impeded, the germination rate declined. Peanuts need a cumulative temperature of 200-300℃ from sowing to seedling emergence. Under normal circumstances, the seed absorbs 40% to 60% of its own weight in order to sprout, and 4 times the weight of the seed needs to be consumed by the time the seedling emerges. Seedling emergence of the most suitable soil water holding capacity of 50% 6O%, less than 40% or more than 70% will affect the normal germination and seedling emergence.

(2) roots, stems, branches and leaves

1. Root growth and rhizoma formation Peanut roots are composed of primary roots, lateral roots and many secondary roots. After the germination of the seed, the embryonic root grows quickly and y into the soil to become the main root, the main root grows four rows of lateral roots, a clear cross arrangement, the lateral roots on the growth of many secondary fine roots, forming a strong conical root system. The depth of the main root can reach more than l meter, or even about 2 meters, but the main root group is distributed in the 10-30 cm soil layer. The lateral distribution of the root system can reach more than 60 centimeters. The roots of peanuts have rhizomes. Generally in the main stem of the seedling to grow five true leaves, the roots will gradually form rhizomes. Root tumors formed at the beginning of the nitrogen fixation capacity is weak, with the growth of the plant, nitrogen fixation capacity gradually enhanced, to the blooming period of nitrogen fixation capacity is the strongest, is the period of the most nitrogen for peanuts. 4/5 of the nitrogen needed by peanuts is supplied by the rhizomes.

2. The growth of the main stem and branches After the peanut seedling emerges from the soil, the terminal bud grows into the main stem. The main stem of the peanut is erect, usually with 15-25 internodes and a height of 15-75 centimeters. The height of the main stem is used in peanut production areas as a simple indicator of individual peanut development and population size. The height of the main stem is 40-50 centimeters; more than 60 centimeters means that the growth is too vigorous, the group is too large, and it is very easy to fall; less than 30 centimeters is the performance of poor growth and weak growth. In recent years, mu yield of about 350 kg of high-yield fields, the main stem height of more than 40 centimeters, some of which are in the 50-60 centimeters. Peanut is a multi-branched crop. Usually the branches growing on the main stem are called the first branch, and the branches growing on the first branch are called the second branch, and so on. The first two branches of the first meristem grow from the leaf nodes and are opposite, called the first pair of lateral branches, while the above lateral branches are alternate. Because the third and fourth lateral branches The internodes of the inserted stem nodes are very short, as if opposite, so it is customary to call the second pair of lateral branches. When the main stem produced four lateral branches, called the group planting period. The first and second pair of lateral branches is the main part of peanut flowering pods, accounting for about 70% of the total number of pods 90%, so its development is good or bad on the yield impact is great. Because the peanut flowering and pods are mainly concentrated in the first and second pair of lateral branches and their branches, so too much branching, especially in the late branching too much, in the production of practical significance. At present, in Shandong Province, some common type clustered peanut high-yield plots per mu branching number is generally in the 20-30 million; intermediate varieties of Xuzhou 68-4, the total number of points per acre technology about 10 a 19 million, single-plant branching 9 or so.

3. Leaf growth The leaves of peanuts can be divided into incomplete metamorphosis leaves and complete leaves (i.e. true leaves) two categories. Each branch of the first or first and second section of the leaves are incomplete metamorphosis leaves, called "bracts" or "scale leaves". Each node of the inflorescence bears an elongated peach-shaped bract, and each flower has a bifurcate bract on the stem. The true leaves of the peanut are pinnately compound, divided into blade, petiole and stipule. The leaflets in the middle of the main stem on the same plant have the shape inherent in the variety, which can be used as a basis for identifying the type of peanut. Leaf pillows are affected by light intensity, expansion pressure changes, so that the relative four leaflets, at night or cloudy days close themselves, the next morning or sunny days and reopen, this phenomenon is known as sensory night movement or sleep movement. Different types of peanuts have obvious differences in leaf color. The same variety, leaf color shade often due to external conditions and internal nutritional status changes and changes, therefore, peanut leaf color changes can be used as a diagnostic indicator of water, fertilizer status and plant internal nutritional status. The main stem of spring peanut can bear more than 20 pieces of true leaves. The growth process of peanut true leaves: after the seedling emerges from the ground, the two true leaves unfold first, when the third true leaf of the main stem unfolds, a leaf on the first pair of lateral branches unfolds at the same time, and then every time the main stem grows a leaf, the first pair of lateral branches grows a leaf at the same time. After the leaf unfolds, it basically stops elongating.

4. Root and stem growth and environmental conditions of the relationship between the peanut root growth, the need for loose soil, humidity suitable soil conditions. Sandy loam, loose soil, good aeration, conducive to root development and rhizoma formation. Soil moisture for the maximum water holding capacity of 50% to 60% is appropriate, if less than 40%, the root growth is slow, the formation of rhizoma less, or even no rhizoma, stem and leaf growth is also inhibited; if the water holding capacity reaches 80%, not only the root distribution is shallow, reduce the plant drought resistance, and easy to cause the above-ground growth. Stem and leaf growth in addition to the requirements of suitable nutrients, water conditions, but also requires high temperatures and sufficient light. Temperature more than 31 ℃ or less than 15 ℃, peanut stems and leaves will basically stop growing, the temperature dropped to 23 ℃ below, growth is slower, the temperature at 26 ℃ about the fastest growth. In addition, peanuts in low light conditions, the main stem internodes long, less branching; good light conditions can make the plant grow robust, compact internodes, more branches.

(C) Flower bud differentiation When the lateral branches of peanut seedlings grow 2-4 true leaves, flower buds begin to differentiate. The regimentation period is a period of massive differentiation of flower buds, and the flower buds differentiated at this time are mostly effective flowers that can bear full pods. A flower bud from the beginning of differentiation to flowering, generally need 20-30 days, multi-grain type and pearl pea type peanut shorter, common type flower growth. Peanut bud differentiation process, the pearl bean type, for example, can be divided into the following periods: bud differentiation (25) days before flowering; calyx differentiation (20 days before flowering); stamens, carpels, petal differentiation (15 days before flowering); ovules, anthers, differentiation (10 days before flowering); floral expansion (7-10 days before flowering); floral maturity (l-3 days before flowering). Peanut bud differentiation is closely related to environmental conditions. Adequate nitrogen supply, suitable soil moisture (maintaining the maximum soil water holding capacity of about 60%), adequate light, conducive to the differentiation of flower buds, for early flowering, more flowers to lay a good foundation; on the contrary, the differentiation of flower buds will be seriously inhibited, delayed flowering, flowering is reduced.

(D) flowering and needle

1. flower morphology structure The flowers of peanuts are hermaphroditic complete flowers, racemes, bearing in the main stem or lateral branches of the leaf axils between the pedicel. Each inflorescence usually can open 2-7 flowers, more than 15 flowers. The entire floral apparatus is divided into five parts: bracts, calyx, corolla, stamens and pistil.

2. Flowering and fertilization Peanut buds expand before flowering, usually in the evening before the day of flowering, the sepals split, revealing yellow petals, to the night calyx rapidly elongate, to the next morning when the flower can be as long as 3-6 cm. Flowers mostly open at 5-7 am. One to five hours before flowering, the anthers will be open to disperse pollen, pollination. Pollination can be fully fertilized in about 12 hours after pollination. After flowering and fertilization, the corolla wilts in the afternoon of the same day. The order of flowering of peanuts, generally from the bottom up, from inside to outside, around the turn to open or open at the same time. However, in the case of prolonged drought and rain, the order of flowering is out of order. Peanut flowering type, according to the first branch on the inflorescence bearing situation can be divided into two categories: one is a continuous flowering type, that is, the main stem blooms, side branches whether or not re-branching, each node can bloom. The other type is the alternate-flowering type, in which the main stem generally does not flower, the first and second nodes of the lateral branches branch, the third and fourth nodes flower, the fifth and sixth nodes branch again, and the seventh and eighth nodes flower, with branches and inflorescences appearing alternately. The common type of large peanut "Penglai a nest of monkeys" is such. Peanuts have a long flowering period and more flowers. In general field production, the number of flowers on a single plant in 50-200. Flowering period of early maturing species from the beginning to the final flower 60-70 days, late maturing species 90-120 days. During the whole flowering period, the period with the most flowers is the blooming period. Continuous flowering type varieties in the beginning of flowering 10 days after the full flowering period; alternate flowering type varieties in the beginning of flowering 20-30 days after the full flowering period. Although the amount of flowering peanuts, but the effective flowering period of the amount of flowering only accounted for about 60% of the total amount of flowering. Regardless of the type of variety of peanut flowers, the base of the two pairs of lateral branches of the amount of flowering accounted for more than 80% of the total amount of flowers 90%.

(E) the elongation of fruit needles and soil peanut flowering and fertilization, the ovary stem part of the meristematic tissue cells rapidly divided, the formation of the ovary stalk. Ovary at the tip of the ovary stalk, the tip of which is needle-like, so the ovary and the ovary stalk collectively known as the fruit needle. Fruit needle growth has to the ground, the tip of the epidermal cells lignified cap-shaped, to protect the ovary into the soil fruiting. Fruit needles begin to elongate slowly, and then gradually accelerate, the plant base of the fruit needles about 4-6 days after the soil, in the high nodes of the fruit needles in the soil about 10 days or more. Fruit needle elongation after 10 centimeters, elongation slows down, into the soil ability to reduce, often due to a long time not into the soil and stop growing. Plant base internode flowering early, from the ground near, most of the fruit needles can man soil fruiting; plant upper flowers bloom late, far from the ground, fruit needles often can not man soil, even if the man soil often due to late, low temperature, affecting the development of the ovary, can not form pods. Usually, the peanut needle rate (accounting for the number of flowers) 30% to 70%, into the needle rate is not high for complex reasons. First, the flower organ is incomplete, not fertilized; second, the flowering temperature is too high or too low; third, the relative humidity of the air is less than 50%, seriously affecting the needle rate. The depth of fruiting needles into the soil varies according to the type of variety and the site of implantation. Pearl bean type and multi-grain type peanut, fruit needle into the soil about 2-4 cm; common type peanut deeper, about 4- 7 cm; Longsheng type peanut, fruit needle people deeper.

(F) peanut flowering under the needle and the relationship between environmental conditions Peanut flowering under the high water requirements, the most sensitive response. In 5 a 15 cm soil layer, to soil water holding capacity of 60% 70% is appropriate. When the soil water holding capacity is lower than 50%, the number of flowering is significantly reduced, or even interrupted flowering; when the soil moisture reaches 80%, it will cause the stem and leaves to grow in vain, and the flowering is reduced. Fruit needles into the soil need moist air and loose soil, drought often causes fruit needles can not people soil, the formation of a large number of ineffective needle. Peanut flowering down the needle needs a lot of mineral nutrition, especially nitrogen and phosphorus two elements. Nitrogen can effectively promote flowering, phosphorus can increase the pre-effective flower, to prevent early plant failure. Peanut flowering under the needle period of high temperature requirements, to the average daily temperature of 25-26 ℃ is most suitable. Below 22 ℃ or higher than 30 ℃, the number of flowering decreased significantly, and the flowering is not uniform. If the temperature drops suddenly to about 12 ℃, the flower development and fertilization will be seriously affected. Tianjin after mid-August flowers, a significant portion of the lower temperature due to the lowering of the development of fruit needle; even under the needle, but also can not be fruit. Therefore, in cultivation to promote peanut early into full bloom, to improve the results rate is of great significance. Peanut flowering under the needle period with sufficient light is to ensure that the flower early, flower more, flower Qi important conditions. In case of rainy, weak light, plant growth is weak, the number of flowers will be significantly reduced. Appropriate shortening of light can promote flowering, can make the beginning, full bloom and final flowering period earlier.

(VII) pod development and maturation After the peanut fruit needle in the soil, the ovary began to develop to form pods. From the beginning of the expansion of the ovary to pod maturity, the whole process can be roughly divided into two stages, namely, pod expansion stage and filling stage. The former stage is mainly manifested in the rapid increase in pod size. Fruit needles in the soil, about 10 days that is the chicken head-shaped young fruit, 10-20 days, pod volume growth is the fastest, about 20-30 days after the soil, pod volume that is grown to the maximum limit. But at this time the pod water content is more, the dry weight increase is not fast, the pods are mainly soluble sugar, oil is very little, the degree of lignification of the shell is low, the pods are smooth and white. The latter stage is mainly characterized by the rapid growth of pods (mainly seeds in weight), sugar reduction, oil content increased significantly. Fruit needles into the soil after 50-6O days or 60-70 days dry weight growth close to stop. During this period, the hull becomes thicker and harder, the seed coat gradually thinner, showing the variety of the original color, in the pod development at the same time, the differentiation of the embryonic apparatus is completed. Pod development on the requirements of environmental conditions: above ground flowering, underground fruit, which is the main characteristics of peanut different from other crops. The development of peanut fruiting requires environmental conditions such as moistness, darkness, oxygen, nutrients and mechanical stimulation. Moisture is one of the basic conditions for pod development. Lack of moisture causes the ovary to shrivel and stop growing; too much water or waterlogged conditions will also inhibit pod development, resulting in small fruit, less fruit, and more blighted and rotten fruit. The soil moisture required for pod development is 50% to 60% of the maximum soil water holding capacity. Darkness and mechanical stimulation are indispensable conditions for pod development. Peanut fruit needle if it has been suspended without making it into the soil, no matter how much elongation, never expand and fruit. Mechanical stimulation of the soil has an effect on the development of the pods. Suitable temperature and sufficient air are also important conditions for pod development. The lowest temperature of the fruiting layer soil during pod development is 15-17℃, the highest temperature is 37-39℃, and the appropriate temperature is 25-33℃. A well-aerated soil is conducive to pod development. Whether the development of pods can achieve large and full, and the nutrient status of the fruiting layer of soil has a close relationship. Therefore, mineral nutrients in the soil of the fruiting layer, especially rich in phosphorus and calcium, have a better effect on promoting the expansion and fullness of pods.