Cultivation method of saplings of Chinese sausages

Abstract

The invention discloses a method for cultivating saplings of Chinese sausage, which comprises the following steps: taking mature black brown fruit pods on the saplings of Chinese sausage, drying in the shade, breaking the fruit pods, and taking out robust and full seeds; the seeds are put into a gauze bag or a mesh bag, and then the gauze bag or the mesh bag is put into hot water to be soaked for 24 h; a square black seedling raising tray is adopted; the matrix is drenched thoroughly, a hole is punched in the middle of the matrix, one seed is placed in each hole, earthing is conducted, and then the hole tray is placed in a plastic greenhouse to promote normal growth of the seedlings; when the seedlings grow 1-2 pairs of true leaves, the seedlings are transplanted into small bags, black film bags are adopted for seedling raising, and red soil and burned soil are mixed to serve as a matrix; when the seedlings grow to about 50cm, timely field planting is carried out, white non-woven fabric planting bags are adopted, red soil is adopted as a matrix, and fertilization and weeding are carried out in time. According to the method, the physiological dormancy characteristics of the seeds can be broken, the budding and seedling raising time is shortened, the seedling emergence efficiency is improved, and the problems that the Chinese sausage tree seedlings are long in breeding time and weak in growth are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of plant seedling cultivation, and in particular to a method for cultivating sausage seedlings. Background Art

[0002] Cassiafistula is a deciduous tree of the genus Cassia in the Leguminosae family, 10 to 15 meters tall, with a breast diameter of 35 cm. The twigs are thin. There are 4 to 8 pairs of leaflets, which are broadly ovate or elliptical-ovate, 8 to 20 cm long, with a gradually obtuse tip and a cuneate base. The leaflets are covered with hair on both sides, which later fall off. Cassiafistula is a rare ornamental tree species and has been widely cultivated as a greening seedling in recent years.

[0003] At present, the seedling breeding technology of sausage tree is generally to directly raise the seedlings in the seedling bags and then plant them in the field. This method has the following defects: (1) low germination rate. The germination speed is slow and inconsistent when the seedlings are directly bred in the seedling bags. The substrate is also prone to compaction during the later growth period. (2) root damage. During the process of transplanting to small bags and planting in large bags, the root system will be damaged, and the absorption function of the seedlings will be affected, resulting in slow growth, and may even die due to the inability of the root system to recover normally. (3) long adaptation period after planting. After the seedlings are planted in large bags, they need a certain amount of time to adapt to the new growth environment. During this adaptation period, the seedlings may stagnate in growth and the leaves may turn yellow, affecting their growth rate and overall quality. Summary of the invention

[0004] The purpose of the present invention is to provide a method for cultivating sausage tree seedlings, which can break the physiological dormancy characteristics of seeds, shorten the germination and seedling raising time, and improve the seedling raising efficiency, thereby effectively solving the problems of long breeding time and weak growth of sausage tree seedlings.

[0005] The above technical objectives of the present invention are achieved through the following technical solutions:

[0006] A method for cultivating sausage seedlings comprises the following steps:

[0007] Step 1: Seed collection: Take the mature dark brown fruit pods from the sausage tree, place them in a ventilated, cool and dry room, spread them out and dry them in the shade for 5 to 7 days, then break the fruit pods to take out the strong and full seeds, and remove the shriveled and broken seeds;

[0008] Step 2: Soak the seeds: first put the seeds into a gauze bag or a mesh bag, then put them into 80-90℃ hot water, stir quickly for 1-2 minutes to heat the seeds evenly, then pour out the hot water, replace it with 55-65℃ hot water and soak for 24 hours, wash off the transparent film on the surface and sow in time;

[0009] Step 3: Seedling tray cultivation: The seedling tray uses a square black seedling tray, and the sowing medium is a mixture of sandy loam and red soil;

[0010] Step 4, on-demand sowing: first, water the substrate thoroughly, then make a hole in the middle of the substrate, which is slightly larger than the seed and 2-3 cm deep, place one seed in each hole, cover with 2-3 cm of soil, and then place the plug tray in a plastic greenhouse to keep warm, moisturize, prevent rain erosion, keep the substrate and seeds moist, and prevent the substrate from drying and hardening. When the seeds grow small buds, place the plug tray under a shading net with a sunlight penetration ratio of 50%, which is conducive to ventilation and light transmission, and pay attention to watering to promote the normal growth of the seedlings;

[0011] Step 5: Transplant to small bags: When the seedlings grow 1-2 pairs of true leaves, remove the shade net and transplant them to small bags. Use black film bags to grow seedlings, and use a mixture of red soil and burnt soil as the substrate to allow them to grow under natural light conditions.

[0012] Step 6. Planting in large bags: The survival rate of sausage tree seedlings is relatively high before they sprout in spring. Choose spring seedling raising. By the spring of the second year, the seedlings will grow to about 50 cm in height and should be planted in time. Use white non-woven planting bags and red soil as the substrate. Fertilize and weed in time. Further: In step three, the ratio of the mixture of sandy loam and red soil is 1:1.

[0013] Further: in step three, the substrate is disinfected with quicklime before being placed in the plug tray, and the seedbed is disinfected with a 5g / L potassium permanganate aqueous solution before sowing.

[0014] By adopting the above technical solution, diseases can be prevented from occurring in seedlings.

[0015] Further: In step five, according to the growth of seedlings, 5g / L compound fertilizer aqueous solution can be used for fertilization once a week. The fertilization time should be carried out in the morning, and the seedlings should be washed with water in the afternoon. When the seedlings grow to the point where they need to be transplanted and planted, stop fertilizing.

[0016] Further: in step five, the specification of the black film bag is 10 cm×14 cm, and the matrix mixing ratio is 80% red soil: 20% burnt soil.

[0017] Further: The specifications of the white non-woven planting bag are 30cm×35cm, and after the seedlings are planted, they should be gently lifted up after covering with soil. When planting on a sunny day, sufficient water should be poured to allow the roots to take root.

[0018] By adopting the above technical solution, the root system of the seedlings can be stretched and made firm.

[0019] Further: In step 6, the fertilization process is as follows: 3-5 kg ​​of decomposed farmyard manure or 0.25 kg of compound fertilizer is mixed with the topsoil as base fertilizer. After planting, the soil is loosened and weeded once in spring and autumn each year, and topdressing is applied once each time. The fertilizer is compound fertilizer, and the fertilizer application rate is 250-350 kg / hm 2 .

[0020] In summary, the present invention has the following beneficial effects:

[0021] First, the present invention can break the physiological dormancy characteristics of seeds, shorten the germination and seedling raising time, and improve the seedling raising efficiency, which effectively solves the problem of long breeding time and weak growth of sausage tree seedlings;

[0022] Second, the present invention performs primary screening from seed collection and processing, which can ensure the quality of seedlings to a certain extent;

[0023] Thirdly, the present invention adopts plug tray seedling raising and then transplanting to seedling raising bag, and the seedling raising time is greatly shortened compared with the seedling raising time of traditional seedling raising bag. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the on-site germination of sausage tree seeds in a plug tray of the present invention;

[0025] Figure 2 This is a schematic diagram of the scene in which the sausage tree seedling of the present invention grows 1 to 2 pairs of true leaves;

[0026] Figure 3 It is a schematic diagram of the root state of the sausage tree seedling of the present invention when it is transplanted into a small bag;

[0027] Figure 4 It is a schematic diagram of the scene of planting sausage tree seedlings in a large bag according to the present invention;

[0028] Figure 5 It is a comparison table of data results of Examples 1-3 of the present invention and the control group. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0030] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by terms such as “upper”, “lower”, “left”, “right”, “front”, “back”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0031] Embodiment 1

[0032] Reference Figure 1-4 , a method for cultivating sausage seedlings, comprising the following steps:

[0033] Step 1: Seed collection: Take the mature dark brown fruit pods from the sausage tree, place them in a ventilated, cool and dry room, spread them out and dry them in the shade for 5 to 7 days, then break the fruit pods to take out the strong and full seeds, and remove the shriveled and broken seeds;

[0034] Step 2: Soaking seeds: First, put the selected plump seeds into a gauze bag or a mesh bag, then put them into 80℃ hot water, stir quickly for 1-2 minutes to heat the seeds evenly, then pour out the hot water, replace it with 55℃ hot water and soak for 24 hours, wash off the transparent film on the surface and sow in time;

[0035] Step 3, seedling tray: the seedling tray uses a square black seedling tray, and the sowing medium is a mixture of sandy loam and red soil in a ratio of 1:1. After disinfection with quicklime, it is placed in the seedling tray. Before sowing, the seedbed is disinfected with a 5g / L potassium permanganate aqueous solution;

[0036] Step 4, on-demand sowing: first, water the substrate thoroughly, then make a hole in the middle of the substrate, which is slightly larger than the seed and 2-3 cm deep, place one seed in each hole, cover with 2-3 cm of soil, and then place the plug tray in a plastic greenhouse to keep warm, moisturize, prevent rain erosion, keep the substrate and seeds moist, and prevent the substrate from drying and hardening. When the seeds grow small buds, place the plug tray under a shading net with a sunlight penetration ratio of 50%, which is conducive to ventilation and light transmission, and pay attention to watering to promote the normal growth of the seedlings;

[0037] Step 5, transplant to small bags: When the seedlings grow 1-2 pairs of true leaves, remove the shade net, put the matrix mixed with 80% red soil and 20% burnt soil into a black film bag with a specification of 10cm×14cm, and then transplant the seedlings together with the seedling matrix into the black film bag for seedling cultivation, and grow them under natural light conditions. At the same time, according to the growth of the seedlings, fertilize once a week with a 5g / L compound fertilizer aqueous solution. The fertilization time should be carried out in the morning, and the seedlings should be washed with water in the afternoon. When the seedlings grow to the point where they need to be transplanted and planted, stop fertilizing;

[0038] Step 6: Planting in large bags: The survival rate of sausage tree seedlings is relatively high before they sprout in spring. Choose spring seedling raising. In the spring of the second year, when the seedlings grow to about 50cm, they should be planted in time. Put the planting soil with red soil as the matrix into a 30cm×35cm white non-woven planting bag, and then transplant the seedlings with the seeding matrix into the white non-woven planting bag, and then cover the soil. After covering the soil, gently lift the seedlings up to stretch the root system and make it firm. If planting on a sunny day, water the roots sufficiently, and fertilize and weed in time;

[0039] For fertilization, 3kg of decomposed farmyard manure or 0.25kg of compound fertilizer should be mixed with the topsoil as base fertilizer. After planting, loosen the soil and weed once in spring and autumn each year, and apply topdressing once each time. The topdressing fertilizer should be compound fertilizer, and the fertilizer application rate should be controlled at 250kg / hm2 .

[0040] Embodiment 2

[0041] Reference Figure 1-4 , a method for cultivating sausage seedlings, comprising the following steps:

[0042] Step 1: Seed collection: Take the mature dark brown fruit pods from the sausage tree, place them in a ventilated, cool and dry room, spread them out and dry them in the shade for 5 to 7 days, then break the fruit pods to take out the strong and full seeds, and remove the shriveled and broken seeds;

[0043] Step 2: Soaking seeds: First, put the selected plump seeds into a gauze bag or a mesh bag, then put them into 85℃ hot water, stir quickly for 1-2 minutes to heat the seeds evenly, then pour out the hot water, replace it with 60℃ hot water and soak for 24 hours, wash off the transparent film on the surface and sow in time;

[0044] Step 3, seedling tray: the seedling tray uses a square black seedling tray, and the sowing medium is a mixture of sandy loam and red soil in a ratio of 1:1. After disinfection with quicklime, it is placed in the seedling tray. Before sowing, the seedbed is disinfected with a 5g / L potassium permanganate aqueous solution;

[0045] Step 4, on-demand sowing: first, water the substrate thoroughly, then make a hole in the middle of the substrate, which is slightly larger than the seed and 2-3 cm deep, place one seed in each hole, cover with 2-3 cm of soil, and then place the plug tray in a plastic greenhouse to keep warm, moisturize, prevent rain erosion, keep the substrate and seeds moist, and prevent the substrate from drying and hardening. When the seeds grow small buds, place the plug tray under a shading net with a sunlight penetration ratio of 50%, which is conducive to ventilation and light transmission, and pay attention to watering to promote the normal growth of the seedlings;

[0046] Step 5, transplant to small bags: When the seedlings grow 1-2 pairs of true leaves, remove the shade net, put the matrix mixed with 80% red soil and 20% burnt soil into a black film bag with a specification of 10cm×14cm, and then transplant the seedlings together with the seedling matrix into the black film bag for seedling cultivation, and grow them under natural light conditions. At the same time, according to the growth of the seedlings, fertilize once a week with a 5g / L compound fertilizer aqueous solution. The fertilization time should be carried out in the morning, and the seedlings should be washed with water in the afternoon. When the seedlings grow to the point where they need to be transplanted and planted, stop fertilizing;

[0047] Step 6: Planting in large bags: The survival rate of sausage tree seedlings is relatively high before they sprout in spring. Choose spring seedling raising. In the spring of the second year, when the seedlings grow to about 50cm, they should be planted in time. Put the planting soil with red soil as the matrix into a 30cm×35cm white non-woven planting bag, and then transplant the seedlings with the seeding matrix into the white non-woven planting bag, and then cover the soil. After covering the soil, gently lift the seedlings up to stretch the root system and make it firm. If planting on a sunny day, water the roots sufficiently, and fertilize and weed in time;

[0048] For fertilization, 4kg of decomposed farmyard manure or 0.25kg of compound fertilizer should be mixed with the topsoil as base fertilizer. After planting, the soil should be loosened and weeded once in spring and autumn each year, and topdressing should be applied once each year. The topdressing fertilizer should be compound fertilizer, and the fertilizer application rate should be controlled at 300kg / hm2. 2 .

[0049] Embodiment 3

[0050] Reference Figure 1-4 , a method for cultivating sausage seedlings, comprising the following steps:

[0051] Step 1: Seed collection: Take the mature dark brown fruit pods from the sausage tree, place them in a ventilated, cool and dry room, spread them out and dry them in the shade for 5 to 7 days, then break the fruit pods to take out the strong and full seeds, and remove the shriveled and broken seeds;

[0052] Step 2: Soaking seeds: First, put the selected plump seeds into a gauze bag or a mesh bag, then put them into 90℃ hot water, stir quickly for 1-2 minutes to heat the seeds evenly, then pour out the hot water, replace it with 65℃ hot water and soak for 24 hours, wash off the transparent film on the surface and sow in time;

[0053] Step 3, seedling tray: the seedling tray uses a square black seedling tray, and the sowing medium is a mixture of sandy loam and red soil in a ratio of 1:1. After disinfection with quicklime, it is placed in the seedling tray. Before sowing, the seedbed is disinfected with a 5g / L potassium permanganate aqueous solution;

[0054] Step 4, on-demand sowing: first, water the substrate thoroughly, then make a hole in the middle of the substrate, which is slightly larger than the seed and 2-3 cm deep, place one seed in each hole, cover with 2-3 cm of soil, and then place the plug tray in a plastic greenhouse to keep warm, moisturize, prevent rain erosion, keep the substrate and seeds moist, and prevent the substrate from drying and hardening. When the seeds grow small buds, place the plug tray under a shading net with a sunlight penetration ratio of 50%, which is conducive to ventilation and light transmission, and pay attention to watering to promote the normal growth of the seedlings;

[0055] Step 5, transplant to small bags: When the seedlings grow 1-2 pairs of true leaves, remove the shade net, put the matrix mixed with 80% red soil and 20% burnt soil into a black film bag with a specification of 10cm×14cm, and then transplant the seedlings together with the seedling matrix into the black film bag for seedling cultivation, and grow them under natural light conditions. At the same time, according to the growth of the seedlings, fertilize once a week with a 5g / L compound fertilizer aqueous solution. The fertilization time should be carried out in the morning, and the seedlings should be washed with water in the afternoon. When the seedlings grow to the point where they need to be transplanted and planted, stop fertilizing;

[0056] Step 6: Planting in large bags: The survival rate of sausage tree seedlings is relatively high before they sprout in spring. Choose spring seedling raising. In the spring of the second year, when the seedlings grow to about 50cm, they should be planted in time. Put the planting soil with red soil as the matrix into a 30cm×35cm white non-woven planting bag, and then transplant the seedlings with the seeding matrix into the white non-woven planting bag, and then cover the soil. After covering the soil, gently lift the seedlings up to stretch the root system and make it firm. If planting on a sunny day, water the roots sufficiently, and fertilize and weed in time;

[0057] For fertilization, 5kg of decomposed farmyard manure or 0.25kg of compound fertilizer should be mixed with the topsoil as base fertilizer. After planting, loosen the soil and weed once in spring and autumn each year, and apply topdressing once each time. The topdressing fertilizer should be compound fertilizer, and the fertilizer application rate should be controlled at 350kg / hm 2 .

[0058] Set up a control group

[0059] Reference Figure 1-4 , a method for cultivating sausage seedlings, comprising the following steps:

[0060] Step 1: Seed collection: Take the mature dark brown fruit pods from the sausage tree, place them in a ventilated, cool and dry room, spread them out and dry them in the shade for 5 to 7 days, then break the fruit pods to take out the strong and full seeds, and remove the shriveled and broken seeds;

[0061] Step 2: Soak the seeds: Soak the selected plump seeds in cold water for 24 hours, wash off the transparent film on the surface and sow them in time;

[0062] Step 3: Seedling tray cultivation: The seedling tray uses an ordinary seedling tray, and the sowing medium is a mixture of sandy loam and red soil;

[0063] Step 4: Seeding: First, make a hole in the middle of the substrate, which is slightly larger than the seed and 2 to 3 cm deep. Put a seed in each hole and cover it with 2 to 3 cm of soil. Then place the plug tray in a plastic greenhouse. When the seeds sprout, place the plug tray in an environment that is conducive to ventilation and light transmission to promote the normal growth of the seedlings.

[0064] Step 5, transplant to small bags: When the seedlings grow 1-2 pairs of true leaves, remove the shade net, transplant the seedlings into ordinary film bags for seedling cultivation, and grow them under natural light conditions. At the same time, fertilize with compound fertilizer solution according to the growth of the seedlings. When the seedlings grow to the point where they need to be transplanted and planted, stop fertilizing.

[0065] Step 6: Planting in large bags: The survival rate of sausage tree seedlings is relatively high before they sprout in spring. Choose spring seedling raising. In the spring of the second year, when the seedlings grow to about 50 cm, they should be planted in time, and then transplanted into ordinary planting bags and covered with soil. If they are planted on sunny days, they should be watered enough to take root, and fertilized and weeded in time;

[0066] For fertilization, use well-rotted farmyard manure or compound fertilizer mixed with topsoil as base fertilizer. After transplanting, loosen the soil and weed once in spring and autumn each year, and apply topdressing once each time. Choose compound fertilizer for topdressing and control the amount of fertilizer applied.

[0067] Data description: Examples 1-3 and the control group sowed 200 seeds (refer to Figure 5 )

[0068]

[0069] Figure 5

[0070] The following is a description of the indicators in the table:

[0071] Number of seeds sown: Record the number of saplings seeds initially sown in each group.

[0072] Number of seedlings: the actual number of seedlings that grow after a certain period of time.

[0073] Germination rate: calculated by the ratio of the number of seedlings to the number of seeds sown, reflecting the germination ability of seeds.

[0074] Observation period: the number of days from the beginning of observing the growth of seedlings to the end of the observation.

[0075] Leaf health score: 1 point indicates that the leaves are yellow, have a large number of spots and are unhealthy; 5 points indicate that the leaves are emerald green and have no obvious diseases.

[0076] Incidence rate of diseases and insect pests: The percentage of seedlings infected with diseases and insect pests to the total number of seedlings is counted.

[0077] Root development status score: 1 point means the root system is weak and underdeveloped; 5 points means the root system is strong, with many root hairs and evenly distributed.

[0078] Overall quality score of seedlings: Taking all the above indicators into consideration, a subjective score is given to the overall quality of the seedlings.

[0079] Result analysis:

[0080] Compared with the conventional cultivation methods of the control group, the cultivation methods adopted by the three experimental groups achieved better results in promoting seed germination, accelerating seedling growth and improving seedling quality.

[0081] Although there were certain differences in various indicators among the three experimental groups, the overall performance was better than that of the control group, indicating that different optimization measures had a positive impact on the cultivation of sausage seedlings. The results of the control group pointed out the shortcomings of conventional cultivation methods. Improvements and optimizations are needed in seed treatment, seedling environment control, pest and disease control, etc. to improve the cultivation quality and efficiency of sausage seedlings.

[0082] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. After reading this specification, those skilled in the art can make creative modifications to this embodiment as needed, but as long as it is within the scope of the claims of the present invention, it will be protected by the patent law.

Claims

1. A method for cultivating sausage seedlings, characterized in that: The following steps are involved: Step 1: Seed collection: Take the mature dark brown fruit pods from the sausage tree, place them in a ventilated, cool and dry room, spread them out and dry them in the shade for 5 to 7 days, then break the fruit pods to take out the strong and full seeds, and remove the shriveled and broken seeds; Step 2: Soak the seeds: first put the seeds into a gauze bag or a mesh bag, then put them into 80-90℃ hot water, stir quickly for 1-2 minutes to heat the seeds evenly, then pour out the hot water, replace it with 55-65℃ hot water and soak for 24 hours, wash off the transparent film on the surface and sow in time; Step 3: Seedling tray cultivation: The seedling tray uses a square black seedling tray, and the sowing medium is a mixture of sandy loam and red soil; Step 4, on-demand sowing: first, water the substrate thoroughly, then make a hole in the middle of the substrate, which is slightly larger than the seed and 2-3 cm deep, place one seed in each hole, cover with 2-3 cm of soil, and then place the plug tray in a plastic greenhouse to keep warm, moisturize, prevent rain erosion, keep the substrate and seeds moist, and prevent the substrate from drying and hardening. When the seeds grow small buds, place the plug tray under a shading net with a sunlight penetration ratio of 50%, which is conducive to ventilation and light transmission, and pay attention to watering to promote the normal growth of the seedlings; Step 5: Transplant to small bags: When the seedlings grow 1-2 pairs of true leaves, remove the shade net and transplant to small bags. Use black film bags to grow seedlings, and use a mixture of red soil and burnt soil as the substrate to allow them to grow under natural light conditions. Step 6. Transplanting in large bags: The survival rate of sausage tree seedlings is relatively high before they sprout in spring. Choose spring seedling raising. By the spring of the second year, the seedlings will grow to about 50 cm in height and should be transplanted in time. Use white non-woven planting bags and red soil as the substrate, and apply fertilizers and weeds in time.

2. The method for cultivating sausage seedlings according to claim 1, characterized in that: In step three, the ratio of sandy loam and red soil mixture is 1:

1.

3. The method for cultivating sausage seedlings according to claim 1, characterized in that: In step three, the substrate is disinfected with quicklime before being placed in the plug tray, and the seedbed is disinfected with a 5g / L potassium permanganate aqueous solution before sowing.

4. The method for cultivating sausage seedlings according to claim 1, characterized in that: In step five, depending on the growth of the seedlings, fertilize once a week with a 5g / L compound fertilizer aqueous solution. Fertilization should be done in the morning, and the seedlings should be washed with water in the afternoon. When the seedlings grow to the point where they need to be transplanted and planted, stop fertilizing.

5. The method for cultivating sausage seedlings according to claim 1, characterized in that: In step five, the specification of the black film bag is 10 cm×14 cm, and the matrix mixing ratio is 80% red soil: 20% burnt soil.

6. The method for cultivating sausage seedlings according to claim 1, characterized in that: In step six, the specifications of the white non-woven planting bag are 30cm×35cm, and after the seedlings are planted, they are gently lifted up after being covered with soil. When planting on a sunny day, sufficient water should be poured to allow the roots to take root.

7. The method for cultivating sausage seedlings according to claim 1, characterized in that: In step six, the fertilization process is as follows: 3-5 kg ​​of decomposed farmyard manure or 0.25 kg of compound fertilizer is mixed with the topsoil as base fertilizer. After planting, the soil is loosened and weeded once in spring and autumn each year, and topdressing is applied once each year. The fertilizer is compound fertilizer, and the fertilizer application rate is 250-350 kg / hm 2 .

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