How to grow rice?

Rice is one of the most important grain crops in China. The national rice planting area accounts for about 30% of the area of grain crops, and the output is close to half of the total grain production.

The growth and development of rice

I. The life of rice

(A) The reproductive process of rice The life of rice, can be divided into two periods of nutritional growth and reproductive growth. Since the seed germination to the beginning of spike differentiation, this period of growth of roots, stems, leaves, known as the nutritive growth period; spike differentiation to spike, this period of spike stems and leaves at the same time, is the nutritional growth and reproductive growth and advancement of the period; after the spike after the flowering of the pollination and seed grouting, fruiting, known as the reproductive growth period; the different reproductive period has a link between each other, the relationship between mutual constraints. Coordinate the relationship between nutritional growth and reproductive growth, is one of the important principles of high-yield rice cultivation.

1. rice fertility rice from seedling to maturity called fertility.

2. Fertility stage of rice

(l) temperature-sensitive rice every completion of a stage of development; need a minimum total heat, for the growing point of qualitative changes necessary for biochemical reactions and plant growth. This total heat is expressed in terms of effective cumulative temperature, active cumulative temperature and total cumulative temperature. Different types of rice varieties have certain requirements for cumulative temperature and are fairly stable. Different varieties require different cumulative temperatures, but the cumulative temperatures required for the reproductive growth period do not vary much among varieties, mainly because the cumulative temperatures required for the nutritive growth period are different. Late-maturing varieties, the completion of nutritional growth requirements of the cumulative temperature more. The cumulative temperature required for each reproductive period of rice is stable, so when the temperature rises, the time to meet the required cumulative temperature becomes shorter, shorter reproductive period; when the temperature decreases, the time to meet the required cumulative temperature becomes longer, longer reproductive period. This is the temperature-sensitive nature of rice, also known as the temperature-sensitive stage.

(2) light-sensitive rice is a short-day crop, the flowering of the induction is mainly the role of the long dark period, must exceed a certain critical dark period in order to cause a qualitative change in the growing point, from nutrient growth to reproductive growth. Light shortening, dark period lengthening, complete photoperiod induction fast, young spike will be early differentiation. Light prolongation, dark period shortening, completion of photoperiod induction slow, spikelet differentiation delay. This is the light sensitivity of rice, also known as light-sensitive stage. Different varieties of photosensitivity are different, early maturing species less days, late maturing species more days.

(ii) the formation of rice yield rice yield is composed of three factors: the number of spikes per unit area, the number of grains per spike and dry grain weight. These three factors, respectively, are formed in different reproductive periods.

1. The formation of the number of spikes The number of spikes per unit area is composed of the number of plants, the number of tillers per plant, tiller spike rate. The number of plants is determined by the density of transplanting and transplanting survival rate, the basis of which is in the rice field period. Therefore, good seedling breeding, strong seedling breeding, in order to ensure that the seedling transplanting fast, tillering early, into the spike more. The key period to determine the number of spikes per unit area is at the tillering stage. On the basis of strong seedlings and reasonable planting, the number of spikes per mu depends on the number of tillers per plant and the rate of tillers. -The earlier the tillers are born, the more likely they are to become spikes. The later the tiller is born, it is not easy to become a spike. So actively promote early tillering, appropriate control of late tillering, is the basic requirements of rice tillering cultivation.

2. The formation of the number of grains The key period to determine the number of grains per spike is in the long spike period. The size of the spike, the number of grains, mainly depends on the number of spikelets formed in the process of spikelet differentiation and spikelet fruiting rate. In the process of spikelet formation, such as nutrients can not keep up, often stop halfway through the development, the formation of abortive spikelets, reducing the fruiting rate, resulting in a small spikelets. The basic requirement of cultivation in the long spike period is to cultivate a strong spike and prevent the failure of the spikelet.

3. The formation of grain weight determines the grain weight and final yield in the fruiting period. Rice grain weight is composed of grain size and maturity. The size of the kernel is constrained by the size of the hull, and the maturity depends on the accumulation of fruiting and filling material. The accumulation of substances in the grain is mainly determined by the amount of photosynthetic products accumulated during this period. If the rice appears to be early senescence or greediness, as well as the influence of adverse climatic factors, it will be poorly grouted, affecting the maturity, resulting in empty grains, reducing the grain weight and affecting the yield. Therefore, to promote grain size, grain fullness, and to prevent empty grain, is the basic requirement of cultivation during the fruiting period. The above three yield factors, in the process of rice growth and development, have a relationship of mutual constraints. General number of spikes per mu more than a certain range, with the increase in the number of spikes, the number of grains per spike and grain weight will have a tendency to decline. Therefore, high rice yield is the number of spikes, the number of grains and grain weight contradictory unity. Its essence is the group and individual contradictory unity.

Two, rice seedling growth and development of rice in the seedling field growth period, called the seedling period. Seedling growth can be divided into the seed germination and seedling growth.

(a) the shade of the rice seed The growth of rice begins with the seed germination. When the rice seed absorbs water and expands, the radicle breaks through the seed shell to reveal the white spot, called "white" or "chest"; when the radicle extends up to the length of the seed, or the germ extends up to half of the length of the seed, it is called germination. The conditions for seed germination are as follows.

1. moisture rice seed germination, the first need to absorb enough water. When the seed water absorption up to 25% of its own weight, it began to sprout. Absorption of water fast and slow and water temperature, high water temperature absorption fast, low water temperature absorption slow.

2. Temperature The lowest temperature of rice germination, japonica 10 ℃, the optimal temperature of 20-25 ℃, this temperature germination neat and robust. The highest temperature of 40 ℃. Therefore, rice germination requires the temperature to maintain 30-35 ℃, after breaking the chest down to 20-25 ℃, to promote the root bud Qi Zhuang.

3. Air rice seeds in the anaerobic layer of water can also germinate, but this germination is not normal, often shoots grow fast, while the root growth is slow. Because the rice seed in the presence of oxygen for respiration to obtain enough energy to germinate. Rice normal germination from the air to absorb oxygen for respiration, called aerobic respiration; when the lack of oxygen from the seed organic matter to take oxygen for respiration, called anaerobic respiration. So the rice seed in the normal germination situation, the first growth of roots, after the growth of buds, on the contrary, there are buds without roots.

(2) seedling growth characteristics

1. Above ground growth of the rice seed germination seedlings, the first is wrapped in the young shoots outside the bud sheath out of the ground, become the sheath leaf. This leaf is cylindrical, not with leaves, and no chlorophyll. Bud sheath elongation to a certain extent, from which draw out a leaf, with chlorophyll, leaf blade is very small, only see the leaf sheath, called incomplete leaf. When this leaf reaches a length of about l centimeter, the seedling field appears green, and it is called seedling emergence, or greening. After that, every 2-3 days, there will be l leaf growth, and there are leaf blades and leaf sheaths, which is called complete leaf, and when the third complete leaf unfolds, it is called the "three-leaf stage". At this time, the nutrients in the seed endosperm are exhausted, and the seedling enters independent life, so it is called the "latex stage".

2. Subterranean growth of rice seed germination, the first from the embryonic root downward extension of the seed root, such as nails as vertical rooted in the soil. Seed germination seedlings, mainly by it to absorb water and nutrients. Then in the germinal sheath node began to develop roots, the bud sheath node roots generally have 5 articles. First grow 2, 1-2 days later and grow 2 in a symmetrical position, followed by l, like a chicken claw, seedling growth in the early stage of the seedling mainly rely on this kind of root, from the release of the leaf to a leaf - heart period formation. After three leaves, the roots grow from incomplete leaves and complete leaf nodes in turn, and are uniformly called "nodal roots". It is thick and has aeration organization. Therefore, after three leaves, you can always keep the water layer in the rice field.

3. Seedling growth period of environmental conditions

( l) temperature requirements Japonica rice seedling minimum temperature of 12 ℃, indica rice seedling minimum temperature of 14 ℃. Under these temperature conditions, the seedling emergence rate is low and slow. After the emergence of the average daily temperature of about 20 ℃, the most favorable for cultivating strong seedlings. Too high or too low are unfavorable. If the low temperature reaches 5-7 ℃, it is necessary to prevent cold, otherwise the rice fungus suffers from frost damage.

(2) air requirements Seedlings can grow normally only if there is sufficient oxygen in the seedling field. Seedlings grow and develop poorly under flooding, with fewer roots and weaker seedlings. Especially before the three-leaf period, flooding is not conducive to cultivating strong seedlings, therefore, the seedling nursery process, small water irrigation, do not keep the water layer, is conducive to cultivating strong seedlings. Wet nursery, drought nursery are to cultivate strong seedlings, to meet the requirements of seedling growth on oxygen.

(3) Moisture requirements The need for moisture in the seedling field increases with seedling growth. Seedling before only need to maintain the field maximum water holding capacity of 40% to 50%, can meet the germination, seedling needs. Before the three-leaf period also do not need water layer, soil moisture content of about 70%. After the three period of soil moisture is not less than 80%, low will affect the growth of rice.

(4) light requirements Light is one of the important conditions for cultivating strong seedlings. Because of sufficient light, seedlings can use the carbon dioxide in the air and the water and nutrients absorbed by the roots to synthesize organic matter through photosynthesis for growth and development.

Three, the growth and development of the tillering stage

(a) the growth of the tiller

1. Tiller law There are a number of dense stem nodes at the base of the main stem of rice, which are called tiller nodes. Each node grows l leaves, there is a tiller bud in the axil of the leaf, growing into a tiller. The leaf position where the tiller is born is called the tiller position. Where a tiller grows directly from the main stem, it is called a primary tiller; a tiller that grows from a primary tiller is called a secondary tiller; a tiller that grows from a secondary tiller is called a tertiary tiller. This is the first time that a tiller grows out of a primary tiller, which is called a secondary tiller. Tillers occur in the nodes of the main stem, sequentially from the bottom up. Generally the tillers always appear three leaves away from the parent stem. n leaves extended = n a three-leaf tiller lth leaf emerges.

2. Factors affecting tillering

(l) The occurrence of tillers is related to the nutritional status of seedlings, especially nitrogen nutrition plays a dominant role. Because of the dense sowing in the seedling period, the nutrients and light are insufficient, and most of the tiller buds on the basal node are in a dormant state. The growth center is shifted after nodulation, and the tiller buds on the upper nodes are also latent and do not develop. So generally only the middle node of the tiller node can develop, but also and other factors have a relationship.

(2) Tiller development and temperature related to the optimal temperature for tiller growth is 30- 32 ℃, below 20 ℃ or higher than 37 ℃ on the growth of tiller is not favorable, 16 ℃ below the tiller to stop growth and development.

(3)Tiller occurrence and light related Under natural light, tillering starts 3 days after greening, when given 50% of natural light, tillering starts in 13 days, when the light intensity is reduced to 5% of the natural light intensity, tillering does not occur, and the main stem will also die.

(4) Tiller development and water related in the tiller development needs sufficient water. In case of water shortage or insufficient water, the physiological function of the plant will be reduced and the tiller will not be supplied with enough nutrients, so the tiller will often dry up and die. This is the reason why "yellow seedling will not start till old age". In addition, tillering is also related to the characteristics of varieties, different varieties have different tillering power. In this field, tillering occurs from slow to fast, and then from fast to slow. When 10% of the seedlings in the field have tillers, it is called the beginning of tillering. When the tillers increase the fastest, it is called the tillering stage. When the total number of stems and the final number of spikes in the field are equal, it is called the end of effective tillering. After that, it is called the ineffective tillering period. When the number of tillers in the field reaches the maximum, it is called the highest tillering period.

(2) Leaf growth The growth of rice leaves, the first three leaves are born before tillering, the last three leaves in the long spike period, the rest of the leaves are in the tillering period. How many leaves of the main stem of rice, different varieties of leaf number is different, generally early maturing varieties of the main stem has 12 a 13 leaves, medium maturing varieties have 14 a 15 leaves, late maturing varieties have 16 a 19 leaves. The growth of 3 leaves before tillering, every 3 days or so l leaves. The growth of leaves at the tillering stage, l leaf every 5 days. The growth of leaf blades after nodulation, l leaf every 7-9 days. The size and length of the leaf blade varies, with inverted 4 leaves being the longest in the medium maturing species and inverted 3 leaves being the longest in the early maturing species. There are differences in the length of life of the leaf blade, early l a 3 leaves, life expectancy is only 10-20 days, later with the rise of the leaf position, the life expectancy is gradually increased, the sword leaf life expectancy is the longest, up to about 50-60 days.

(3) root growth tillering period is also the main period of root growth, all the roots from the stem node, known as the first root, the first root on the branching root, known as the second root or the first branching, and later can grow the third and fourth root. All the nodes of rice have the ability to develop roots, and with the birth of leaves, one section develops roots upward. Generally there is a difference of three nodes between rooting and leaf emergence, and the occurrence of meristematic roots, in turn, decreases by one node. Rice roots have aeration organization, this aeration organization and the stem and leaves in the similar organization connected, become the above ground to the root of the oxygen transport pathway, so that rice in the drowning hypoxia can still grow. Rice root development and soil water, fertilizer, gas, heat and other conditions are closely related. Such as the growth of rice roots, the optimal temperature of 28-30 ℃, more than 35 ℃ growth is hindered, less than 15 ℃ growth is weakened, less than 10 ℃ to stop growing.

Four, long spike period of growth and development (nodulation to spike) rice growth and development to the end of tillering, will begin to stalk internode elongation (nodulation) and spike differentiation, until the internode elongation is complete, spike length to spike until, known as the long spike period. Rice this period of nutritional growth and reproduction at the same time, on the one hand, the completion of roots, stems, leaves and other nutrient organs of growth and development, while the young spike differentiation and development, the formation of reproductive organs.

(a) the growth of roots, stems and leaves

1. Root growth rice in the tillering period from the nodes on the adventitious roots, to the joints of this period only the upper nodes continue to produce adventitious roots, mainly from the adventitious roots on the growth of sub-technical roots. This kind of root is y rooted downward. The distribution of roots becomes obovate at the tasseling stage. The total root volume reaches its peak.

2. The growth of stalks After the rice pulling, the above ground several internodes elongation, become obvious visible stalks. Different varieties, the elongation of the nodes are different, early maturing varieties elongation generally 3-4, medium maturing varieties elongation nodes generally 5-6, late maturing varieties elongation nodes generally 6-7. The elongation of the internodes from the bottom up one by one in order, according to which it can promote the base of several internodes in the elongation of the long term to strengthen the management, so that it is short and stout resistance to collapse to seize the high yield.

3. The growth of the leaf rice to the end of tillering into the node, the leaf from about 5 days long l leaf, to every 7-9 days only long 1 leaf; life is also prolonged, the spike period of the leaf up to 40 days or more; and the leaf layer division of labor is obvious. The nutrients produced by the upper leaves are mainly transported to the growth center of young spikes, and the nutrients produced by the lower leaves are mainly used for the growth of internodes and roots. Leaf area and population should be appropriate, such as too early to close the line, will affect the stalks, internodes, root vigor early decline, fruiting is not good. If the rows are closed too late, the leaf area is too small, and the nutrients are made less and accumulated less, which will also affect the strong stalks and big spikes. Generally to grasp the sword leaf tip closure line is more appropriate.

(II) young spike differentiation and development of rice spike is panicle, there is a main peduncle called spike axis, spike axis on the section, called spike section, the next section, called spike neck section. Spike node on the long branching, called primary branching peduncle. And then branching long secondary branch peduncle. From the primary and secondary branching pedicel on the long branching pedicel, the end bearing spikelets (flowers). Spike differentiation process can be divided into a number of periods, and the delimitation method is different, more concise delimitation method is introduced below.

1. The pedicel differentiation period includes the first bract primordial differentiation, primary pedicel differentiation and secondary pedicel differentiation in three periods. The first bract primordial differentiation period, refers to the base of the growth cone, sword leaf primordial above, the formation of a ring-like protrusion, is the first bract primordial. It is a sign of the differentiation of the young spike. In the first peduncle differentiation stage, the growth cone expands and transverse lines appear; each primary peduncle protuberance is differentiated from the bottom upward, and white bract hairs grow at the first bract, marking the end of primary peduncle differentiation. During the second peduncle differentiation, secondary peduncle protuberances appear on both sides of the primary peduncle primordium, in the opposite order of the primary peduncle, proceeding from top to bottom. At the end of secondary pedicel differentiation, the young spikelet is completely covered by bract hairs. The length of the young spikelet is 0.5-1.0 millimeters.

2. Spikelet differentiation includes two periods of spikelet primordial differentiation and androecium formation. When the upper primary branching pedicel tip of the guard glume and the proximity of the floret outer glume protuberance, for the beginning of spikelet differentiation. Then the inner and outer glume primordia were differentiated. When the androgynophore appears, the androgynophore formation stage is entered. The order of differentiation develops from the top to the base. A branch peduncle, then the apical spikelet first differentiation, and then from the base upward differentiation.

3. Meiotic division includes two periods of pollen mother cell formation and pollen mother cell meiosis. That is, from the development of pollen mother cells within the anthers, meiosis, tetrad formation of the whole process. The spikelet develops to both effective and degenerate poles, and the degenerate spikelet stays in the stage of androecium formation and becomes a sterile spikelet or glume.

4. Pollen filling completion period This is the spikelet length stereotypes, spikelets up to the full length, mainly pollen grains of the content of the filling, pollen becomes yellow, the inner and outer glumes all become green, male and female spores are all developed and mature, the rice plant began to draw spikes and flowers.

(C) young spike differentiation field identification

1. Inferred from the perennial spiking period young spike began to differentiate, roughly 30-35 days before spiking, secondary pedicel differentiation roughly 20-25 days before spiking, meiosis, roughly 10-15 days before spiking. It varies according to varieties, regions and cultivation conditions.

2. Inferred from the situation of nodulation From top to bottom, the fifth internode elongation when the young spikelets began to differentiate, the fourth internode elongation when the spikelet differentiation, the third internode elongation when the meiosis, the second internode elongation when the formation of pollen grains and the emergence of spikes.

3. Inferred from the length of spikelets and spikelets When the spikelet length is 0.5-1.0 mm, and the spikelet is covered with bract hairs, it is the period of secondary peduncle differentiation. When the spikelet length is 5-10 mm, it is the stage of androecium formation. When the spikelet is 1.5-4.0 cm long, it is the pollen mother cell formation period. When the young spikelets and spikelets reach about half of the full length, it is the meiotic stage. Young spikelets and spikelets close to the full length of the pollen content of the pollen content of the completion of the period.

Fifth, the growth and development of the fruiting period of rice from spike to maturity is called the fruiting period. This process is about 30-55 days, different varieties of different days.

(a) flowering and fertilization of young rice spikes from the scabbard leaf sheath, called tasseling. It takes about 3-5 days for all the spikes to come out. The whole field has 10% of the rice plant out of the leaf sheath half, for the beginning of the spike period. When 50% of the plants produce spikes, it is the tasseling period. When 80% of the plants produce spikes, it is the spike stage. Spike The top spikelet blooms in 1-2 days after the scabbard leaf sheaths are exposed. The order of flowering is the same as that of spikelet development. In the case of a spike, it is from top to bottom. In the case of a pedicel, first the tip and then from the base to the tip. Each flower opens the glumes, splits the anthers, disperses the pollen, and spits the anthers out of the glumes after pollination. Each flower opens and closes in 1-2 hours. Flowering usually occurs at 9-10 a.m., peaks at 11-12 a.m., and stops at 2-3 p.m. The optimum temperature for flowering is 30-35 degrees Celsius. The optimum temperature for flowering is 30-35°C, with a minimum temperature of 15°C. A spike takes 5-8 days to flower. It takes about 5-8 days for a spike to bloom. About 2-7 minutes after pollination, pollen germinates and extends out of the pollen tube and enters the ovary along the stigma, and then reaches the ovule, drills into the bead hole, and enters the embryo sac, where the pollen tube ruptures at the apex and releases two male nuclei, one of which fuses with the two polar nuclei to form a large nucleus, i.e., the prokaryotic endosperm. A male nucleus enters into the egg cell for fertilization, and the fertilized egg develops into an embryo in the future. The fertilization process is usually completed 9 to 18 hours after flowering.

(II) Fertilization

1. Grain formation The ovary begins to elongate on the lth day after fertilization, and the grains reach the maximum length in 6-7 days after flowering, at which time the organs of the embryo are also largely completed, and begin to have the ability to germinate. 8-10 days, the grains reach their maximum thickness. The fresh weight of rice grains grows fastest in 10 days after flowering and reaches the maximum value in 25-28 days. Peak increase in dry weight of rice grains is 15-20 days after flowering, and reaches the maximum value 25-45 days after flowering.

2. Grain maturity Rice grain maturity, generally divided into milky, wax maturity, complete maturity of several periods. Generally 3-5 days after flowering into the milky ripening period, at this time there are starch deposits in the kernel is milky white. On this basis, the white emulsion becomes thicker until it becomes hard and waxy, and the husk turns yellow, which is called the wax ripening period. In the wax ripening after about 7-8 days into the maturity period, this time the rice hard solid, back green recedes into white, rice life to the end.

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