How to grow rice?
Growth and development of rice
First of all, the life span of rice
(1) The whole life process of rice can be divided into two stages: vegetative growth and reproductive growth. From seed germination to young spike differentiation, roots, stems and leaves grow during this period, which is called vegetative growth period; The young panicle differentiates to heading, and the stem and leaf of the young panicle grow at the same time, which is a period of simultaneous vegetative growth and reproductive growth. The grain filling and fruiting period after heading, flowering and pollination is called reproductive growth period; There are interrelated and restrictive relationships between different growth periods. Coordinating the relationship between vegetative growth and reproductive growth is one of the important principles of high-yield cultivation of rice.
1. The growth period of rice is called the growth period from emergence to maturity.
2. The growth stage of rice
(l) Every development stage of temperature-sensitive rice has been completed; The biochemical reaction and plant growth necessary for the qualitative change of growth point require the minimum total heat. This total heat is expressed by effective accumulated temperature, active accumulated temperature and total accumulated temperature. Different types of rice varieties have certain requirements for accumulated temperature, and it is quite stable. Different varieties have different requirements for accumulated temperature, but there is little difference between varieties in reproductive growth period, mainly in vegetative growth period. Late-maturing varieties have more accumulated temperature to meet the requirements of vegetative growth. The required accumulated temperature in each growth period of rice is stable, so the time to reach the required accumulated temperature becomes shorter and the growth period becomes shorter when the temperature rises. When the temperature decreases, the time to reach the required accumulated temperature becomes longer and the growth period is prolonged. This is the temperature sensitive period of rice, also known as the temperature sensitive period.
(2) Photosensitive rice is a short-day crop, and the induction of flowering is mainly in the long dark period. To cause the qualitative change of growing point, from vegetative growth to reproductive growth, it must exceed a certain critical dark period. The light was shortened, the dark period was prolonged, the photoperiodic induction was completed quickly, and the young panicle differentiated early. Light prolonged, dark period shortened, photoperiodic induction completed slowly, and young panicle differentiation was delayed. This is the photosensitivity of rice, also known as photosensitivity period. Different varieties have different photosensitivity, less days of early maturity and more days of late maturity.
(II) Formation of Rice Yield Rice yield consists of three factors: number of panicles per unit area, number of grains set per panicle and dry grain weight. These three factors are formed in different growth periods.
1. The number of spikes per unit area consists of the number of plants, the number of tillers per plant and the tillering rate. The number of plants depends on the transplanting density and survival rate, based on the seedling stage. Therefore, only by cultivating seedlings well and strengthening the quality of seedlings can we ensure that seedlings return to green quickly, tiller early and have more ears after transplanting. The key period to determine the number of spikes per unit area is tillering stage. On the basis of strong seedlings and reasonable close planting, the number of panicles per mu depends on the number of tillers per plant and tillering rate. The earlier tillers are born, the greater the possibility of panicle formation. Late tillers are not easy to ear. Therefore, it is the basic requirement of rice cultivation at tillering stage to actively promote early tillering and properly control late tillering.
2. The key period of grain number per panicle formation is long panicle stage. The panicle size and grain number mainly depend on the number of spikelets formed during the differentiation of young panicles and the spikelet setting rate. In the process of spikelet formation, if the nutrients can't keep up, the development will often stop halfway, forming abortive spikelets, reducing the seed setting rate and leading to the decrease of spikelets. The basic requirement of long spike cultivation is to cultivate strong stalks and big spikes to prevent spikelets from aborting.
3. The formation of grain weight determines the grain weight and final yield during grain filling. The grain weight of rice consists of grain size and maturity. The grain size is restricted by the size of chaff, and the maturity depends on the accumulation of grain filling materials. The accumulation of substances in seeds mainly depends on the accumulation of photosynthetic products during this period. If rice is premature aging or greedy for green growth, as well as adverse climatic factors, it will not fill well, affect maturity, cause empty grains, reduce grain weight and affect yield. Therefore, promoting big grain fullness and preventing empty grains are the basic requirements of cultivation at filling stage. The above three yield factors restrict each other in the process of rice growth and development. Generally, when the number of spikes per mu exceeds a certain range, the number of grains per spike and grain weight tend to decrease with the increase of spikes. Therefore, high yield of rice is the unity of contradiction and opposition among panicle number, grain number and grain weight. Its essence is the contradiction and unity of opposites between groups and individuals.
Second, the growth and development of rice seedlings The period when rice grows in the seedling field is called seedling stage. Seedling growth can be divided into rice seed germination and seedling growth.
(1) Shading of rice seeds The growth of rice begins with seed germination. When rice seeds absorb water and swell, radicle breaks through the seed shell and exposes white spots, it is called "exposing white" or "breaking chest"; Germination occurs when the radicle reaches the length of the seed, or the germ reaches half the length of the seed. The conditions for seed germination are as follows.
1. Moisture Rice seeds need to absorb enough water first. When the water absorption of seeds reaches 25% of their own weight, they begin to germinate. The speed of water absorption is related to the water temperature. High water temperature absorbs water quickly, while low water temperature absorbs water slowly.
2. Temperature The lowest temperature for rice germination is 65438 00℃, and the optimum temperature for japonica rice germination is 20-25℃, so the germination is neat and robust. The maximum temperature is 40℃. Therefore, the germination temperature of rice is required to be kept at 30-35℃, and then decreased to 20-25℃ after the breast is broken, so as to promote the vigorous growth of roots and buds.
3. Air rice seeds can germinate under the oxygen-free water layer, but this germination is abnormal, often the buds grow fast and the roots grow slowly. Because rice seeds can germinate only when they breathe oxygen and get enough energy. When rice germinates normally, it draws oxygen from the air to breathe, which is called aerobic respiration; When lacking oxygen, taking oxygen from seed organic matter to breathe is called anaerobic respiration. Therefore, in the case of normal germination, rice seeds grow roots first, then buds, and vice versa.
(2) Growth characteristics of seedlings
1. When rice seeds growing above the ground germinate and emerge, the bud sheath wrapped outside the bud first extends out of the ground and becomes a sheath leaf. This kind of leaf is tubular, with no leaves and no chlorophyll. When the bud sheath is stretched to a certain extent, L leaves are drawn from it, which are green and small, and only the leaf sheath is seen, which is called incomplete leaves. When this leaf is about 1 cm long, the seedling field appears green, which is called emergence or turning green. After that, L leaves will grow every 2-3 days, with leaves and leaf sheaths, which are called complete leaves. When the third complete leaf unfolds, it is called "trilobal stage". At this time, the nutrients in the endosperm of the seed are exhausted and the seedlings enter an independent life, so it is called "weaning period".
2. When the rice seeds growing underground germinate, they first extend downward from the radicle and grow into seed roots, which are inserted vertically in the soil like nails. When seeds germinate and emerge, they mainly rely on it to absorb water and nutrients. Then, the roots begin to grow on the bud nodes, which usually have five. Two strains began to grow. After 1-2 days, the two strains grew symmetrically, and then the L strain grew like chicken feet. The seedlings are mainly formed by this root in the early stage of seedling growth, from the leaf release stage to the leaf heart stage. After three leaves, roots grow from incomplete leaves and complete leaves in turn, which are collectively called "nodal roots" It's strong and has ventilation tissue. Therefore, the water layer can always be maintained in the seedling field after three leaves.
3. Requirements of seedling growth period on environmental conditions
(1) temperature requires that the minimum temperature for japonica rice to emerge is 65438 02℃, and that for indica rice is 65438 04℃. Under this temperature condition, the emergence rate is low and the speed is slow. The average daily temperature after emergence is about 20℃, which is most beneficial to cultivate strong seedlings. Too high or too low is not good. If the low temperature reaches 5-7℃, it is necessary to keep warm, otherwise the rice fungus will be frozen.
(2) The air requires the seedling field to have enough oxygen to grow normally. Seedlings grow poorly under flooding, with few roots and weak seedlings. Especially before the three-leaf stage, flooding is not conducive to cultivating strong seedlings. Therefore, in the process of seedling raising, small amount of irrigation is beneficial to cultivate strong seedlings. Wet seedling raising and dry seedling raising are aimed at cultivating strong seedlings and meeting the requirements of oxygen for seedling growth.
(3) Water requirement The water requirement of the seedling field increases with the growth of seedlings. Before emergence, only 40%-50% of the maximum field storage capacity can meet the needs of germination and emergence. No water layer is needed before the trilobal stage, and the soil water content is about 70%. After the third stage, the soil moisture is not less than 80%, which will affect the growth of rice.
(4) Light needs light, and light is one of the important conditions for cultivating strong seedlings. Because of abundant sunshine, seedlings can use carbon dioxide in air and water and nutrients absorbed by roots to synthesize organic matter through photosynthesis for growth and development.
Third, the growth and development at tillering stage.
(A) the growth of tillers
1. The law of tillering occurrence There are several dense stem nodes at the base of the main stem of rice, which are called tillering nodes. L leaves grow on each node, and there are 1 tiller buds in the axils of leaves, which grow into tillers. The leaf position of tillering is called tillering position. All tillers that grow directly from the main stem are called primary tillers, those that grow from primary tillers are called secondary tillers, and those that grow from secondary tillers are called tertiary tillers. And so on. Tillering occurs in the internodes of the main stem from bottom to top. Generally, tillers always appear three leaves away from the mother stem. N leaf extension = n- the first leaf appears in the three-leaf tiller.
2. Factors affecting tillering
(1) The occurrence of tillering is related to the nutritional status of seedlings, especially nitrogen nutrition plays a leading role. At seedling stage, most of the tillering buds on the basal nodes are dormant due to over-dense sowing and insufficient nutrients and light. After jointing, the growth center shifts, and the tillering buds on the upper nodes also lurk and do not germinate. Therefore, only the tillering node in the middle node can develop, but it is also related to other factors.
(2) The optimum temperature for tillering growth is 30-32℃, and it is not conducive to tillering growth if it is lower than 20℃ or higher than 37℃, and it will stop growing if it is lower than 16℃.
(3) Tillering is related to light. Under natural light, tillering began 3 days after turning green, and when the light intensity was 50% of natural light, tillering began in 13 days. When the light intensity drops to 5% of the natural light intensity, tillering will not occur and the main stem will die.
(4) The occurrence of tillering is related to water content, and sufficient water content is needed during tillering. When there is water shortage or water shortage, the physiological function of plants decreases, and the tillers are not supplied with enough nutrients, which often dries up and dies. This is the truth of "letting Huang Miao live for a while until she is old". In addition, tillering is also related to variety characteristics, and there are differences in tillering ability among different varieties. Tillering in this field experienced a process from slow to fast, and then from fast to slow. When 10% seedlings tiller in the whole field, it is called early tillering stage. The time when tillers grow fastest is called tillering peak period. When the total number of stems in the whole field is equal to the number of the last ear, it is called the effective tillering termination period. Hereinafter referred to as ineffective tillering stage. When the number of tillers in the whole field reaches the maximum, it is called the highest tillering stage.
(2) Leaf growth The growth of rice leaves, the first three leaves were born before tillering, the last three leaves grew at long panicle stage, and the rest grew at tillering stage. The number of main stems and leaves of rice varies with varieties. General early-maturing varieties 12- 13 leaves, medium-maturing varieties 14- 15 leaves, and late-maturing varieties 16- 19 leaves. With the growth of three leaves before tillering, one L leaf grows every three days or so. Leaf growth at tillering stage, once every 5 days. Leaf growth after jointing stage, L leaves every 7-9 days. The size and length of leaves are different. The middle-mature species has the longest 4 leaves, and the early-mature species has the longest 3 leaves. The life span of leaves is different. The life span of L-3 leaves is only 10-20 days at early growth. Later, with the increase of leaf position, the life span gradually increased, and the life span of flag leaf was the longest, reaching about 50-60 days.
(3) The tillering stage of root growth is also the main stage of root growth. Any root that grows from the stem node is called the first root, the branch root that grows on the first root is called the second root or the first branch, and the third root and the fourth root can grow later. All nodes of rice have the ability to take root, and with the birth of leaves, they take root section by section. Generally, the difference between hairy roots and leaves is 3 knots, and the appearance of branched roots decreases by 1 knot. There are aeration tissues in the roots of rice, which are connected with similar tissues in stems and leaves, and become a way to transport oxygen from the aboveground parts to the roots, so that rice can still grow under the condition of flooding and hypoxia. The development of rice root system is closely related to water, fertilizer, gas and heat in soil. For example, the optimum temperature for rice root growth is 28-30℃. Above 35℃, the growth will be hindered, but below 15℃, it will be weakened, and below 10℃, it will stop growing.
Fourth, the growth and development of the long panicle stage (from jointing to heading) When the rice grows and develops to the end of tillering, it begins to elongate the internodes of the stem (jointing) and differentiate the young panicles until the elongation of the internodes is completed, and the young panicles grow to the panicles, which is called the long panicle stage. During this period, the vegetative growth and reproduction of rice go hand in hand, on the one hand, the growth and development of vegetative organs such as roots, stems and leaves are completed, and at the same time, the young panicles differentiate and develop to form reproductive organs.
Growth of roots and leaves
1. Rooted rice grows adventitious roots at tillering stage, and only the upper nodes continue to grow adventitious roots at jointing stage, mainly from adventitious roots. This root is deeply rooted. By heading stage, the distribution of roots became inverted oval. The total root amount reached the peak.
2. After the rice jointing stage, the stem grows, and several internodes above the ground elongate and become obviously visible stems. Different varieties have different elongation nodes, with 3-4 elongation nodes for early-maturing varieties, 5-6 elongation nodes for middle-maturing varieties and 6-7 elongation nodes for late-maturing varieties. The elongation of internodes is carried out one by one from bottom to top. According to it, the management of several internodes of the base can be strengthened at jointing stage to make it short and strong, lodging resistant and high yield.
3. Growth of leaves After rice enters the jointing stage at the end of tillering, the leaves grow from L leaves of about 5 days to every 7-9 days 1 leaf; The life span has also been prolonged, and the leaves at the ear stage have reached more than 40 days; And the division of labor in the leaf layer is obvious. The nutrients produced by the upper leaves are mainly transported to the young panicles in the growth center, 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. If the line is closed too early, it will affect the stubble of stem and internode, the root system will be premature and the result will be poor. Too late closure, too small leaf area and less nutrient production and accumulation will also affect strong stalks and big ears. Generally, it is more appropriate to master the tip of sword leaf dew.
(2) Young panicles differentiate into panicles of the genus Oryza, with a main stem called panicle axis, a node on the panicle axis called panicle node, and the last node called panicle neck node. There are long branches on the ear nodes, which are called primary branches. Re-branching of long secondary branches. Branchlets grow from primary branches and secondary branches, and spikelets (flowers) are born at the ends. The process of rice ear differentiation can be divided into several periods with different strokes. Here are more concise strokes.
1. The branching differentiation stage includes three stages: the first bud primordium differentiation, the first branching differentiation and the second branching differentiation. The differentiation stage of the first bud primordium refers to the formation of annular protrusions above the base of the growth cone and the healthy base, which is the first bud primordium. This is a sign of young spike differentiation. In the first branching and differentiation stage, the growth cone expands and horizontal stripes appear; From bottom to top, the primary branch primordium process was differentiated, and the first bud grew a white bud, indicating that the primary branch differentiation was terminated. In the stage of secondary branching and differentiation, the secondary branching primordia appear on both sides of the primary branching primordia, and the order is opposite to that of the primary branching, proceeding from top to bottom. At the end of secondary branch differentiation, all young panicles are covered by bracts. The young spike is 0.5- 1.0 mm long.
2. The spikelet differentiation stage includes two stages: spikelet primordium differentiation and pistil formation. The initial stage of spikelet differentiation is when glume protection and exoglume primordium protrusion of lower floret appear at the top of upper primary branch. And then differentiate into internal and external glume groups. When the pistil primordium appears, it enters the stage of pistil formation. The order of differentiation develops from top to bottom. Spikelets at the top of branches differentiate first, and then differentiate upward from the base.
3. The meiosis stage includes the formation of pollen mother cells and meiosis of pollen mother cells. That is, the development and enrichment of pollen mother cells from anthers, meiosis and tetrad formation. Spikelets develop into effective and degenerated poles, and degenerated spikelets stay in the pistil formation stage and become abortive spikelets or spikelets.
4. At the completion stage of pollen enrichment, the panicle length is fixed and the spikelets reach the full length, mainly because the contents of pollen grains are enriched, the pollen turns yellow, the inner and outer glumes all turn green, the male and female spores all mature, and the rice plants start heading and flowering.
(3) Field identification of young spike differentiation.
1. According to the perennial heading date, it is inferred that young panicles begin to differentiate, about 30-35 days before heading, the secondary branch differentiation is about 20-25 days before heading, and the meiosis period is about 10- 15 days before heading. It varies with varieties, regions and cultivation conditions.
2. According to the jointing situation, the spikelets began to differentiate when the fifth internode was extended from top to bottom, the spikelets differentiated when the fourth internode was extended, meiosis occurred when the third internode was extended, and pollen grains formed and entered the heading stage when the second internode was extended.
3. According to the length of spikelets and spikelets, when the spikelets are 0.5- 1.0 mm long and covered by bracts, it is the second branching and differentiation stage. When the young spike is 5- 10 mm long, it is the pistil formation period. When the young spike length is 1.5-4.0 cm, it is the pollen mother cell formation period. Meiosis occurs when young spikelets and spikelets reach about half of the total length. When the young spike and spikelet are close to the full length, it is the completion period of pollen content enrichment.
Verb (abbreviation of verb) The growth and development of rice during grain filling period is called grain filling period. This process takes about 30-55 days, and the days of different varieties are different.
(1) The young panicle of flowering and fertilization rice protrudes from the sheath of flag leaf, which is called heading. It takes about 3-5 days to pull out all the ears. When half of the leaf sheaths of rice plants in the whole field 10% are pulled out, it is heading stage. There are 50% plants heading, which is the heading stage. When there is 80% heading, it is the full heading stage. The spikelet at the top of the spike will bloom after flag leaf sheath 1-2 days. The order of flowering is the same as that of spikelet development. For one ear, from top to bottom. As far as a branch is concerned, it starts from the top and then goes from the bottom to the top. After each flower opens, cracks, disperses pollen and pollinates, the anther spits out glume. Each flower from opening to closing is 1-2 hours. Generally, it blooms at 9:00- 10 in the morning, peaks at1-12 in the morning and stops at 2-3 pm ... The optimum temperature for flowering is 30-35℃, and the lowest temperature is 65438 05℃. It takes about 5-8 days for an ear to blossom. After pollination, the pollen germinates for about 2-7 minutes, extends out of the pollen tube, enters the ovary along the stigma, reaches the ovule, drills into the micropyle and enters the embryo sac for about 30 minutes. The tip of pollen tube breaks, releasing two male nuclei, and one male nucleus fuses with two polar nuclei to form a large nucleus, that is, embryonic milk pronucleus. A male nucleus enters an egg for fertilization and the fertilized egg will develop into an embryo in the future. Generally, the fertilization process is completed in 9- 18 hours after flowering.
(2) Grouting is firm
1. After fertilization, 1 Tianzifang began to elongate, and the rice grains reached the maximum length on the 6th to 7th day after flowering. At this time, the organs of the embryo are basically completed and begin to germinate. After 8- 10 days, the rice grains reached the maximum thickness. The fresh weight of rice increased fastest within 10 day after flowering, and reached the maximum in 25-28 days. The increase of rice grain dry weight reached the peak on 15-20 days after flowering and reached the maximum on 25-45 days after flowering.
2. Grain maturity of rice is generally divided into milk maturity, wax maturity and complete maturity. Generally, it enters the milk ripening stage 3-5 days after flowering, when the starch deposits in the seeds are milky white. On this basis, the white latex thickens until it becomes waxy and the chaff turns yellow, which is called wax ripening period. When the wax matures for about 7-8 days, it enters maturity. At this time, the rice grains are hard and strong, and the back is blue and white, and the life of rice is over.
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