Breeding method of a bolting-resistant inbred line of carrot

Abstract

The application provides a breeding method of a bolting-resistant carrot inbred line, which comprises the following steps: sowing carrot seed materials in a southern region where carrots cannot complete vernalization in winter in summer and autumn, selecting non-bolting seed roots from the carrot breeding materials in mid-March, transplanting the carrot breeding materials to a northern region, selfing when the carrot breeding materials blossom, and repeating the above steps for three times to obtain the bolting-resistant carrot inbred line. The method can be applied to carrot breeding, directly selects the bolting-resistant carrot inbred line, provides a parent for breeding a new bolting-resistant carrot variety, and provides a reference for breeding other plants in the selection of a bolting-resistant inbred line. The method is simple and easy to operate, and can accelerate the breeding of the bolting-resistant carrot inbred line. The bolting-resistant carrot inbred line used for carrot breeding has the advantages of low cost, good effect, high repeatability and simple operation.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of agricultural and rural technology, and particularly relates to a method for breeding a bolting-tolerant carrot inbred line by using regional ecological and climatic differences. BACKGROUND

[0002] Carrot is one of the top ten vegetables in the world, and is well-known for its rich carotenoids (vitamin A precursor substances) and important economic value. The bolting-tolerant characteristic is an important characteristic of carrot varieties for adapting to early spring cultivation in some ecological regions.

[0003] For breeding a bolting-tolerant hybrid variety, a bolting-tolerant inbred line material is required. The conventional method for breeding a bolting-tolerant inbred line is to plant an existing inbred line in an ecological environment where carrot is prone to premature bolting, so as to identify the bolting tolerance of the inbred line. This method is suitable for identifying and selecting the bolting tolerance of an existing inbred line, provided that the inbred line material is pure enough. If there is no pure inbred line material with bolting tolerance, a bolting-tolerant inbred line needs to be screened out. However, due to the long time required for saving the screened bolting-tolerant plants, at least 6 months, and the poor ability of the saved carrot seed roots to regenerate and root, or even the risk of rotting, the seeds cannot be obtained, and the breeding material is often lost. SUMMARY

[0004] The present application provides a breeding method for a bolting-tolerant carrot inbred line, which selects a southern ecological region where carrot cannot be completely vernalized, selects plants that cannot bolt or bolt late in the region, transports them to a northern region, continues to use low temperature for vernalization, isolates self-pollination to produce seeds, and repeatedly screens the self-pollination in different regions for 3 times to obtain a bolting-tolerant carrot inbred line. The present application establishes an integrated technology for breeding a bolting-tolerant carrot inbred line, achieves the purpose of breeding a bolting-tolerant carrot inbred line, and has the characteristics of good effect and low cost.

[0005] The present application is formed on the basis of years of research on carrot breeding in Tianjin and the central and southern part of Jiangxi, and it is found that some carrot breeding materials in the central and southern part of Jiangxi cannot complete vernalization and bolting or significantly delay bolting. This ecological and climatic characteristic can be used to develop pressure screening of bolting tolerance of carrot. Meanwhile, the screened bolting-tolerant carrot seed roots are planted in Tianjin to continue vernalization, bolting, flowering, and seed maturation.

[0006] The technical solution of the present application is: a breeding method for a bolting-tolerant carrot inbred line, which is carried out in Jiangxi and Tianjin, and specifically includes the following steps:

[0007] Step one, in the summer and autumn of the first year (late August to early September), carrot breeding materials are sowed in the central and southern regions of Jiangxi, and high ridge cultivation is adopted to manage the conventional production cultivation. The carrots are overwintered in situ;

[0008] Step two, in the middle of March of the second year, the carrot breeding materials are screened, and the plants that do not bolt and meet other breeding target traits are selected and shipped to Tianjin for planting. Further springing and bolting are carried out, and when flowering, single plants are isolated for self-pollination. The self-pollination seeds S1 are harvested in the middle and late July.

[0009] Step three, in the summer and autumn of the second year (late August to early September), the self-pollination seeds S1 are sowed in the central and southern regions of Jiangxi. In the middle of March of the third year, the carrot breeding materials are screened, and the plants that do not bolt and meet other breeding target traits are selected and shipped to Tianjin for planting. Further springing and bolting are carried out, and when flowering, single plants are isolated for self-pollination. The self-pollination seeds S2 are harvested in the middle and late July.

[0010] Step four, in the summer and autumn of the third year (late August to early September), the self-pollination seeds S2 are sowed in the central and southern regions of Jiangxi. In the middle of March of the fourth year, the carrot breeding materials are screened, and the plants that do not bolt and meet other breeding target traits are selected and shipped to Tianjin for planting. Further springing and bolting are carried out, and when flowering, single plants are isolated for self-pollination. The self-pollination seeds S3 are harvested in the middle and late July.

[0011] Step five, the self-pollination seeds S3 are sowed and expanded in Tianjin. When the seed roots are harvested, if the target traits of the identified strains are consistent as a whole, it is a self-pollination line of carrot that is resistant to bolting.

[0012] Preferably, the central and southern regions of Jiangxi in step one include Nanfeng, Guangchang, Ningdu, etc.

[0013] Preferably, the carrot breeding materials in step one refer to open pollination varieties or traditional local varieties that are orange and have resistance to bolting.

[0014] Preferably, the conditions for high ridge cultivation in step one are as follows: ridge height 24-26 cm, ridge distance 67-70 cm, ridge surface width 25-30 cm, double rows in one ridge, row distance on the ridge 14.5-15.5 cm, and plant distance 6-8 cm.

[0015] Preferably, the screening method of carrot breeding materials in steps two to four is as follows: 10-20 plants are selected from the plants that do not bolt and have other target traits, the leaves are cut to leave 1-3 cm of the top, and good moisture and ventilation are ensured. The other target traits include carrot root epidermis, phloem, xylem color, no green shoulder, smooth epidermis, root length 15-22 cm, and round and blunt tail.

[0016] The present application has remarkable technical effects due to the adoption of the above technical solutions.

[0017] 1、 Through the preliminary research, it is determined that the carrot cannot be completely through the spring in the south ecological region, and the selected plant has the tolerance to the bolting in the region; then the ecological difference is utilized to transport the bolting-tolerant carrot to the northern region, the low temperature is utilized to pass the spring, the selfing is isolated to produce the seed, and the selfing is repeatedly selected in different places for three times to obtain the bolting-tolerant carrot selfing line.

[0018] 2、 Compared with other methods, the bolting-tolerant material selected by the present application is more reliable; the climate difference and the biological characteristics of the carrot are ingeniously combined, and the breeding process is completely carried out in the open field, the breeding material is selected by the visual method, the cost is low, and the application value is high. The method of the present application is simple and easy to implement, is an integrated technology for selecting the bolting-tolerant carrot selfing line, and the bolting-tolerant carrot selfing line can be efficiently and stably selected by the method.

[0019] 3、 The method for selecting the bolting-tolerant carrot selfing line can be applied to the carrot breeding, directly selects the bolting-tolerant carrot selfing line, provides the parent for breeding the new bolting-tolerant carrot variety, and can provide the reference for selecting the bolting-tolerant selfing line in the breeding of other plants. The method of the present application can accelerate the selection of the bolting-tolerant carrot selfing line, the selected bolting-tolerant selfing line is used for the carrot breeding to prepare the hybrid, has the advantages of low cost and good effect, and is highly reproducible and simple to operate.

[0020] The present application will be further described in detail in combination with the embodiments. DETAILED DESCRIPTION

[0021] Embodiment 1

[0022] The present embodiment is to select a bolting-tolerant carrot selfing line, and the carrot selfing line also has the following target traits: the root skin, phloem and xylem are all deep orange red, the root is round and blunt, and the root length is 15-16 cm. The breeding process is carried out in Nangfeng County, Jiangxi and Tianjin, and specifically includes the following steps.

[0023] Step one, collect and organize the carrot germplasm resources, and select Baoguan (BG) as the carrot breeding material for screening the bolting-tolerant selfing line. The breeding material is an open pollination conventional variety, the root skin, phloem and xylem are all orange red, the root is round and blunt, and there is a great difference in the bolting tolerance, root length and root shape.

[0024] Step two, on August 31, 2018, the selected seeds were sown in Nanfeng County, Jiangxi Province, and were cultivated on high ridges with a ridge height of 25 cm, a ridge distance of 67 cm, and a ridge surface width of 25 cm. The ridges were planted in double rows with a row distance of 15 cm and a plant distance of 7 cm. The ridges were irrigated by drip irrigation, and the carrots were managed by conventional production cultivation. The carrots overwintered in the ground.

[0025] Step three, on March 15-16, 2019, the carrot breeding materials were investigated and screened. Fifteen plants that did not bolt and met other breeding target traits (including: the root epidermis, phloem, and xylem were all deep orange-red, the root end was round and blunt, and the root length was 15-16 cm) were selected. The leaves were cut to leave 2 cm of the top, and the plants were well ventilated and transported to Tianjin for planting. The plants were further subjected to vernalization and bolting, and were managed by conventional field management. When the plants flowered, they were isolated and self-pollinated. After pollination and seed setting, the isolation materials were removed, and the seeds were harvested on July 13, 2019, in Tianjin.

[0026] Step four, the seeds harvested in the same year were sown in Nanfeng County, Jiangxi Province, on September 1, and the work of the first year was repeated. On March 16, 2020, the carrot breeding materials were screened according to the method described in step three. Fifteen plants that did not bolt and met other breeding target traits were selected, the leaves were cut to leave 2 cm of the top, and the plants were well ventilated and transported to Tianjin for planting. The plants were further subjected to vernalization and bolting, and were isolated and self-pollinated when they flowered. The self-pollinated seeds (S2) were harvested on July 13, 2020.

[0027] Step five, the self-pollinated seeds (S2) harvested in the same year were sown in Nanfeng County, Jiangxi Province, on August 31, and the work of the first year was repeated. On March 15, 2021, the carrot breeding materials were screened according to the method described in step three. Fifteen plants that did not bolt and met other breeding target traits were selected, the leaves were cut to leave 2 cm of the top, and the plants were well ventilated and transported to Tianjin for planting. The plants were further subjected to vernalization and bolting, and were isolated and self-pollinated when they flowered. The self-pollinated seeds (S3) were harvested on July 12, 2021, and the seeds had the characteristic of resistance to bolting.

[0028] Step six, on July 30, the self-pollinated seeds (S3) were sown in the Wuqing Innovation Base of the Tianjin Academy of Agricultural Sciences. The plants were managed by conventional field management, and the main target traits of the plant lines were identified when the roots were harvested. The root epidermis, phloem, and xylem were all deep orange-red, the root end was round and blunt, and the root length was 15-16 cm. These traits were consistent as a whole, and the carrot plant line was resistant to bolting. The plant line was named BGd-181.

[0029] Example 2

[0030] The present embodiment is to breed a carrot inbred line with bolting resistance, and also has the following objectives: the flesh root epidermis, phloem and xylem are all orange, the epidermis is smooth, the end is round and blunt, and the root length is 18-19 cm. The breeding process is carried out in Guangchang County, Jiangxi Province and Tianjin, and specifically includes the following steps:

[0031] Step one, collect and organize carrot germplasm resources, and select HY as the breeding material for screening bolting-resistant inbred lines. The breeding material is an open-pollinated conventional variety, the flesh root epidermis, phloem and xylem are all orange, the end is round and blunt, and there are great differences in bolting resistance, root length and root shape.

[0032] Step two, on September 1, 2018, the selected seeds were sown in Guangchang County, Jiangxi Province, and were cultivated on high ridges with a ridge height of 24 cm, a ridge distance of 70 cm, and a ridge surface width of 30 cm. The ridges were planted in double rows, with a row spacing of 15.5 cm and a plant spacing of 8 cm. The ridges were irrigated by drip irrigation, and the carrots were managed in a conventional production cultivation manner. The carrots overwintered in the ground.

[0033] Step three, on March 17, 2019, the carrot breeding materials were investigated and screened, and 20 plants that did not bolt and met the other breeding objective traits (including: the flesh root epidermis, phloem and xylem are all orange, the epidermis is smooth, the end is round and blunt, and the root length is 18-19 cm) were selected. The leaves were cut to leave 3 cm of the top, and good moisture and ventilation were ensured. The plants were shipped to Tianjin for planting, further springing and bolting, and were managed in a conventional field. When flowering, single plant isolation self-pollination was carried out. After pollination and fruiting, the isolation material was removed, and when the seeds were yellow and ripe, the self-pollinated seeds S1 were harvested on July 13 in Tianjin.

[0034] Step four, the self-pollinated seeds S1 harvested in the same year were sown in Guangchang County, Jiangxi Province on August 31, and the work of the first year was repeated. On March 16, 2020, the carrot breeding materials were screened according to the method described in step three, and 20 plants that did not bolt and met the other breeding objective traits were selected. The leaves were cut to leave 3 cm of the top, and good moisture and ventilation were ensured. The plants were shipped to Tianjin for planting, further springing and bolting, and were managed in a conventional field. When flowering, single plant isolation self-pollination was carried out. The self-pollinated seeds S2 were harvested on July 13.

[0035] Step five, the self-pollinated seeds S2 harvested in the same year were sown in Guangchang County, Jiangxi Province on August 30, and the work of the first year was repeated. On March 17, 2021, the carrot breeding materials were screened according to the method described in step three, and 20 plants that did not bolt and met the other breeding objective traits were selected. The leaves were cut to leave 3 cm of the top, and good moisture and ventilation were ensured. The plants were shipped to Tianjin for planting, further springing and bolting, and were managed in a conventional field. When flowering, single plant isolation self-pollination was carried out. The self-pollinated seeds S3 were harvested on July 12, and the seed material had the characteristic of bolting resistance.

[0036] Step six, on August 1, the inbred seeds S3 were sown in the Wuqing Innovation Base of Tianjin Agricultural Academy, and the conventional field management was carried out. When the seed roots were harvested, the main target traits of the strain were identified: the flesh root epidermis, phloem and xylem were orange, the epidermis was smooth, the tail was round and blunt, and the root length was 18-19 cm. These traits were consistent as a whole, that is, the carrot inbred line with tolerance to bolting, and was named HYd237.

[0037] Example 3

[0038] This example is to breed a carrot inbred line with tolerance to bolting, which also contains the target traits: the flesh root epidermis, phloem and xylem are orange, no green shoulder, the epidermis is smooth, the tail is round and blunt, and the root length is 20-21 cm. The breeding process is carried out in Jiangxi Ningdu County and Tianjin, which specifically includes the following steps:

[0039] Step one, collect and organize carrot germplasm resources, and select Maryet (ML-G13) as the breeding material of carrot inbred line with tolerance to bolting. The breeding material is an open pollinated variety, the flesh root epidermis, phloem and xylem are orange, the tail is round and blunt, and there is a big difference in tolerance to bolting, root length and root shape.

[0040] Step two, on September 2, 2019, the selected seeds were sown in Jiangxi Ningdu County, and the high ridge cultivation was carried out. The ridge height was 26 cm, the ridge distance was 68 cm, the ridge surface width was 28 cm, one ridge with double rows, the ridge row distance was 14.5 cm, the plant distance was 6 cm, the drip irrigation was used, the conventional production cultivation was managed, and the carrot was overwintered in the ground.

[0041] Step three, on March 16, 2020, the carrot breeding materials were investigated and selected, and 10 plants which did not bolt and met other breeding target traits (including: the flesh root epidermis, phloem and xylem were orange, no green shoulder, the epidermis was smooth, the tail was round and blunt, and the root length was 20-21 cm) were selected. The leaves were cut to leave 1 cm of top, good moisture and ventilation were done, and were shipped to Tianjin area for planting. Further, after springing and bolting, the conventional field management was carried out, and when flowering, single plant isolation self-pollination was carried out. After pollination and fruiting, the insect-proof net was removed, and when the seeds were yellow and ripe, the inbred seeds S1 were harvested on July 13 in Tianjin.

[0042] Step four, the seeds S1 harvested this year were sown in Jiangxi Ningdu County on August 31, and the work of the first year was repeated. On March 17, 2021, the carrot breeding materials were selected according to the method described in step three, and 10 plants which did not bolt and met other breeding target traits were selected. The leaves were cut to leave 1 cm of top, good moisture and ventilation were done, and were shipped to Tianjin area for planting. Further, after springing and bolting, the conventional field management was carried out, and when flowering, single plant isolation self-pollination was carried out. The inbred seeds S2 were harvested on July 13.

[0043] Step five, the self-pollinated seeds S2 harvested in the same year are sowed in Jiangxi Ningdu County on August 30, and the work in the first year is repeated; on March 15, 2022, the carrot breeding materials are screened according to the method in step three, 10 plants without bolting and with other target traits are selected, the leaves are cut to leave 1cm of the top, good ventilation and moisture are ensured, and the plants are shipped to Tianjin area for planting, and further springing and bolting are carried out, and when flowering, the plants are isolated for self-pollination, and the self-pollinated seeds S3 are harvested on July 14, and the seed material has the bolting resistance characteristic.

[0044] Step six, on July 31, the self-pollinated seeds S3 are sowed in the Wuqing Innovation Base of Tianjin Agricultural Academy of Sciences, and the conventional field management is carried out, and when the root is harvested, the main target traits of the strain are identified: the flesh root epidermis, phloem and xylem are orange, the epidermis is smooth, there is no green shoulder, the tail is round and blunt, and the root length is 20-21cm, and these traits are consistent, that is, the bolting-resistant carrot selfing line, and is named as MLd-G13-19.

[0045] The bolting-resistant carrot selfing line obtained by the method can be used for preparing hybrid combinations to breed new bolting-resistant carrot varieties.

[0046] The above is only a preferred embodiment of the present application, which is used to illustrate the present application, and does not limit the present application. The essence and scope of the present application are limited by the claims. For those skilled in the art, without departing from the essence and scope of the present application, any simple modification, change and equivalent change of the above embodiment according to the essence of the present application, including the screening of bolting-resistant carrot materials in similar regions, etc., are still within the protection scope of the present application.

Claims

1. A method for breeding bolting-resistant carrot inbred lines, characterized in that, The method was conducted in Jiangxi and Tianjin, and specifically includes the following steps: Step 1: From the end of August to the beginning of September of the first year, carrot breeding materials are sown in the central and southern regions of Jiangxi Province, cultivated on raised beds, and overwintered in the local area. Step 2: In mid-March of the second year, carrot breeding materials were screened. Plants that had not bolted and met other breeding target traits were selected and planted in the Tianjin area. After vernalization and bolting, individual plants were isolated for self-pollination when flowering. Self-pollinated seeds S1 were harvested in mid-to-late July. Step 3: From the end of August to the beginning of September of the second year, the self-pollinated seeds S1 were sown in the central and southern regions of Jiangxi Province; in mid-March of the third year, carrot breeding materials were screened, and plants that had not bolted and met other breeding target traits were selected and planted in the Tianjin area. After vernalization and bolting, when flowering, individual plants were isolated for self-pollination, and self-pollinated seeds S2 were harvested in mid-to-late July. Step 4: From the end of August to the beginning of September of the third year, the self-pollinated seeds S2 were sown in the central and southern regions of Jiangxi Province; in mid-March of the fourth year, carrot breeding materials were screened, and plants that had not bolted and met other breeding target traits were selected and planted in the Tianjin area. After vernalization and bolting, when flowering, individual plants were isolated for self-pollination, and self-pollinated seeds S3 were harvested in mid-to-late July. Step 5: Sow and propagate the self-pollinated seeds S3 in the Tianjin area. When the seed roots are harvested, if the target traits of the identified lines are consistent, they are bolting-resistant carrot inbred lines. Other target traits mentioned in steps two through four include that the fleshy root epidermis, phloem, and xylem of the carrot are all orange-red in color, without green shoulders, with a smooth epidermis, a root length of 15-22cm, and a rounded end.

2. The method for breeding a bolting-resistant carrot inbred line according to claim 1, characterized in that, The carrot breeding materials mentioned in step one refer to orange-red, open-pollinating varieties or traditional local varieties that are resistant to bolting.

3. The method for breeding a bolting-resistant carrot inbred line according to claim 1, characterized in that, The conditions for raised bed cultivation described in step one are as follows: ridge height 24-26cm, ridge spacing 67-70cm, ridge width 25-30cm, double rows per ridge, row spacing 14.5-15.5cm, and plant spacing 6-8cm.

4. The method for breeding a bolting-resistant carrot inbred line according to claim 1, characterized in that, The specific screening method for carrot breeding materials described in steps two to four is as follows: select 10 to 20 plants that have not bolted and possess other target traits, cut off the leaves leaving 1 to 3 cm of the top, and ensure proper moisture retention and ventilation.