Method for reducing poison carrying rate of sweet potato seeds and improving propagation multiple of healthy seed potato seedlings by changing planting mode

Abstract

The invention relates to a method for effectively reducing the virus carrying rate of sweet potato seeds and improving the propagation multiple of healthy sweet potato seed seedlings by changing a planting mode, and belongs to the technical field of plant propagation. According to the occurrence rule of the bemisia tabaci in the sweet potato field in the northern potato area, the planting time of seedlings in the sweet potato breeding field and the harvesting time of the seed potatoes are adjusted, namely, a traditional summer planting and autumn harvesting mode is adjusted to be a spring planting and summer harvesting mode, so that the harm of virus transmission insect bemisia tabaci is avoided, and then the virus carrying rate of the seed potatoes of the sweet potatoes is reduced. According to the planting mode provided by the invention, the virus carrying rate of the sweet potato seed potatoes can be reduced, high-quality non-toxic healthy seed potatoes are bred locally, the seed potatoes harvested in summer are used for seedling raising and expanding propagation in winter, the rapid propagation multiple is greatly improved, the seedling breeding cost is reduced, the sweet potato production requirements in northern potato areas can be met, and meanwhile, the economic benefit is increased. The method is of great significance in reducing the breeding and operating risks of seed potato seedlings and improving the prevention and control level of the sweet potato virus diseases.

Description

Technical Field

[0001] The present invention relates to a method for effectively reducing the virus-carrying rate of sweet potato seed tubers and increasing the propagation multiple of healthy seed tubers and seedlings by changing the planting mode, belonging to the technical field of plant propagation. Background Art

[0002] Sweet potato is an important food, feed, and industrial raw material crop. Virus diseases are an important type of diseases that harm sweet potato, which can cause a reduction in sweet potato yield and degeneration of varietal characteristics, seriously endangering sweet potato production. Currently, the most seriously harmful virus in sweet potato production is sweet potato chlorotic stunt virus (SPCSV). SPCSV can form synergistic diseases with many other viruses, causing serious symptoms such as twisted and deformed sweet potato leaves and dwarfing of plants, which can result in a reduction in production of more than 50% or even a complete crop failure. It can be seen that SPCSV causes great harm to sweet potato and severely restricts the development of sweet potato production.

[0003] Sweet potato chlorotic stunt virus SPCSV belongs to the members of the genus Trichovirus in the family Closteroviridae. The SPCSV virus particles are long filamentous, with a particle length of 850 - 950 nm and a diameter of 12 nm. The virus genome is a bipartite single-stranded positive-sense RNA, with a genome size of about 17.6 kb. SPCSV is mainly transmitted by Bemisia tabaci in a semi-persistent manner. The applicant's previous research has shown that the carrying of SPCSV by sweet potato roots (seed tubers) will cause severe symptoms of virus diseases in the seedling stage of sweet potato, which is a key factor for the occurrence of virus diseases in the seedling stage of sweet potato. On this basis, the applicant further conducted in-depth research on the relationship between the occurrence amount and virus-carrying rate of Bemisia tabaci in sweet potato fields and the virus-carrying rate of sweet potato roots (seed tubers), and found that the occurrence amount of Bemisia tabaci in sweet potato fields and the virus-carrying rate of SPCSV are closely related to the virus-carrying rate of sweet potato seed tubers. In the case where both the occurrence amount of Bemisia tabaci and the virus-carrying rate of SPCSV are relatively high, even if virus-free test-tube seedlings without any virus are planted, the virus-carrying rate of sweet potato roots (seed tubers) will still be relatively high. The above research results indicate that the occurrence amount and virus-carrying rate of Bemisia tabaci in sweet potato seed production fields are the key factors affecting the virus-carrying rate of sweet potato seed tubers by SPCSV and the quality of sweet potato seed tubers. Therefore, as long as the Bemisia tabaci in sweet potato seed production fields is effectively controlled, the virus-carrying rate of sweet potato seed tubers can be effectively reduced and the quality of sweet potato seed tubers can be improved.

[0004] At present, the traditional method for breeding potato seeds in the northern potato-growing area is the summer planting and autumn harvesting mode, that is, planting potato seedlings in the middle and late June every year and harvesting potato seeds in the middle and late October. In the following spring, the bred potato seeds are used for seedling propagation and multiplication. However, in recent years, with the large-scale occurrence of the virus-transmitting insect Bemisia tabaci in sweet potato fields, the virus-carrying rate of the bred potato seeds is relatively high and the quality is unqualified. The seedlings grown from these virus-carrying potato seeds will develop serious virus diseases, and the long-distance transportation of virus-carrying potato seeds will also lead to the spread of virus diseases. Therefore, the size of the Bemisia tabaci population in sweet potato breeding fields has become a key factor affecting the virus-carrying rate of sweet potato seeds and the severity of virus diseases during the seedling stage. The traditional potato seedling breeding mode is no longer suitable for the current needs of virus-free and healthy sweet potato production in the northern potato-growing area. In addition, due to the characteristics of Bemisia tabaci such as fast reproduction speed, overlapping generations, and strong drug resistance, it is extremely difficult to control Bemisia tabaci in sweet potato fields. These problems pose great challenges to the breeding of healthy sweet potato seeds and seedlings and the prevention and control of sweet potato virus diseases.

[0005] Under the above background, in recent years, sweet potato researchers have developed a method for breeding potato seeds in cool regions with less occurrence of Bemisia tabaci, such as in the northeast, northwest, and mountainous areas with higher altitudes. Although virus-free and healthy potato seeds can be bred in these regions, there are problems such as high breeding costs (transportation costs, land costs, etc.), short growth periods, low yields, large impacts of adverse weather during the harvest period, and easy rotting of potato seeds due to mechanical damage during long-distance transportation. Therefore, this mode is not suitable for small, medium, and micro potato seedling enterprises, and it is also difficult for large potato seedling companies to adopt this mode. In addition, researchers have also explored the direct use of virus-free sweet potato shoot tips for overwintering rapid propagation, hoping to directly apply virus-free shoot tips to the production breeding mode. However, this mode has problems such as limited breeding conditions, low multiplication multiples, and high costs, which restrict its application in production.

[0006] Therefore, there is an urgent need to create a mode with high efficiency and low cost that can effectively reduce the virus-carrying rate of potato seeds and increase the multiplication multiple of healthy potato seeds and seedlings to meet the production needs of the northern potato-growing area. This is of great significance for effectively reducing the breeding risks of potato seeds and seedlings and the economic losses of potato farmers, as well as improving the prevention and control level of sweet potato virus diseases. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the present invention provides a method for effectively reducing the virus-carrying rate of sweet potato seeds and increasing the multiplication multiple of healthy sweet potato seeds and seedlings by changing the planting mode.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A method for effectively reducing the virus-carrying rate of sweet potato seeds and increasing the multiplication multiple of healthy sweet potato seeds and seedlings by changing the planting mode, which adjusts the seedling planting time and seed potato harvest time in the sweet potato seed breeding field to avoid the harm of the virus-transmitting insect Bemisia tabaci, thereby reducing the risk of potato seeds being infected with viruses.

[0010] The specific method is as follows: The planting time of the seedling is set from late March to early April every year, and the harvesting time of the seed potato is late July of the current year. The seed potatoes harvested in late July of the current year are stored and propagated by seedling in winter of the current year or early spring of the next year.

[0011] The method of the present invention mainly aims at the sweet potato chlorotic stunt virus (SPCSV) infected by the seed potato.

[0012] The beneficial effects of the present invention:

[0013] (1) According to the occurrence law of Bemisia tabaci in the sweet potato fields in the northern sweet potato region, the present invention adjusts the planting time of the seedlings and the harvesting time of the seed potatoes in the sweet potato propagation fields to avoid the harm of the virus-transmitting insect Bemisia tabaci, thereby reducing the risk of the seed potatoes being infected by the sweet potato chlorotic stunt virus SPCSV. That is, the traditional summer planting and autumn harvesting mode (planted in June and harvested in October every year) is adjusted to the spring planting and summer harvesting mode (planted from March to April and harvested in July every year). In this way, the risk of the sweet potato seed potatoes being infected by SPCSV can be greatly reduced, and the quality of the seed potatoes can be guaranteed. The propagated seed potatoes can be stored and propagated by seedling in winter of the current year or early spring of the next year after storage, which can increase the propagation multiple and reduce the breeding cost, and provide an effective means for the breeding of healthy seed potatoes and seedlings and the prevention and control of sweet potato virus diseases.

[0014] (2) By changing the planting mode, the present invention can effectively reduce the virus-carrying rate of the sweet potato seed potatoes SPCSV and increase the propagation multiple of the healthy seed potatoes and seedlings, and avoid many unfavorable factors of propagating seeds in other places (such as in the northeast, northwest and other regions). Compared with directly using virus-free shoot tips to overwinter and propagate, the present invention uses the seed potatoes harvested in summer to propagate by seedling in winter, which greatly increases the rapid propagation multiple and reduces the seedling breeding cost, and can meet the production needs of sweet potatoes in the northern sweet potato region.

[0015] (3) The implementation of the method of the present invention is of great significance for reducing the breeding and operation risks of seed potatoes and seedlings and improving the prevention and control level of sweet potato virus diseases. This method is easy to promote and implement, and has good economic and practical value. Specific implementation mode

[0016] The following further elaborates on the specific implementation mode of the present invention in combination with the embodiments.

[0017] Example 1. Dynamic investigation of Bemisia tabaci in sweet potato fields in the northern sweet potato region

[0018] 1. Investigation time and location

[0019] From 2020 to 2021, experimental sites were continuously set up in Yuanyang, Henan, Yanjiang, Henan, Luanchuan, Henan, Jiaozuo, Henan and Shijiazhuang, Hebei for 2 consecutive years to conduct dynamic investigations on the Bemisia tabaci population. The sweet potato planting area of each experimental site is 666.7 m 2Around, the planting density is 3000 plants / 666.7m 2 Around, with conventional field management. The investigation time for Bemisia tabaci is from April to September every year.

[0020] 2. Investigation method

[0021] The occurrence amount of Bemisia tabaci was investigated by using the yellow sticky trap method. For every 666.7m 2 20 yellow sticky traps were hung as insect-trapping boards, arranged in a Z shape. Each yellow sticky trap was 40×25 cm in size, vertically hung, with the lower edge of the yellow sticky trap 5 - 10 cm higher than the sweet potato plants. The yellow sticky traps were replaced every about 10 days, and the number of Bemisia tabaci trapped on each yellow sticky trap was recorded. After accumulating the number of Bemisia tabaci on the 20 yellow sticky traps and averaging, the average occurrence amount of Bemisia tabaci (heads / trap) at the corresponding time for each test site was calculated (the results are shown in Table 1).

[0022] 3. Results and analysis

[0023] As can be seen from Table 1, during the 2-year test period, no Bemisia tabaci was trapped at the 5 test sites before July 15 of the current year. Among them, in 2020, Bemisia tabaci began to be trapped at the Yuanyang and Luanchuan test sites on August 8, and the occurrence amount of Bemisia tabaci was relatively large from mid-August to late September, which was the peak occurrence period; in 2021, the occurrence of Bemisia tabaci was slightly later, but the peak occurrence period was still from mid-August to late September. The investigation results of the two years showed that sweet potatoes harvested before the end of July were not affected by Bemisia tabaci.

[0024] Table 1 Investigation table on the occurrence dynamics of Bemisia tabaci at different sweet potato field test sites in the northern sweet potato region

[0025]

[0026] Example 2. Relationship between the occurrence amount of Bemisia tabaci in sweet potato fields and the virus-carrying rate of sweet potato roots (seed potatoes)

[0027] 1. The tested sweet potato variety was Shangshu 19, including virus-free test-tube seedlings and pre-basic seedlings of Shangshu 19, all provided by the Institute of Plant Protection, Henan Academy of Agricultural Sciences.

[0028] 2. Use a sterilized scalpel to dig out the potato peel and the connected potato flesh about 1 cm in size in the middle of the potato tuber, grind it into powder with liquid nitrogen, and then extract the total RNA of the sample using the Plant RNAKit kit (Omega BIO-TEK). 3 3. Use RT-PCR for virus detection, record the number of PCR-positive potato tubers, and calculate the virus-carrying rate of seed potatoes according to the following formula.

[0029] Virus-carrying rate of seed potatoes (%) = Number of PCR-positive potato tubers / Total number of tested tubers × 100%.

[0030] Virus-carrying rate of seed potatoes (%) = Number of PCR-positive potato tubers / Total number of tested tubers × 100%.

[0031] 4. In order to study the virus-free sweet potato seedlings in different areas where whiteflies occur, planting experiments were carried out using seedlings with the same background.

[0032] There will be 7 planting sites in 2020 and 5 planting sites in 2021. The planting area of ​​each test site is 666.7m 2 The planting density of sweet potatoes is 3,000 plants / 666.7m 2 The yellow board trap method was used to investigate the occurrence of whiteflies. 2 Hang 20 yellow boards in a Z-shaped arrangement. The size of the yellow boards is 40×25cm. Hang vertically. The lower edge of the yellow boards is 5-10cm higher than the sweet potato plants. Replace the yellow boards every 10 days or so. Investigate and record the number of whiteflies trapped on each insect trap. Add up the number of whiteflies on the 20 yellow boards, and then calculate the average number of whiteflies on each yellow board to obtain the average number of whiteflies (heads / yellow board) at the test point. When the sweet potatoes are harvested, randomly select 100 seed potatoes at each test point for virus testing.

[0033] The results showed that among the seven planting sites in 2020, the average occurrence of whiteflies in Yuanyang and Yanjin test sites was relatively high, at 2226.5 heads / yellow board and 1175.2 heads / yellow board, respectively, and the SPCSV infection rate of the corresponding seed potatoes was also high, at 16.0% and 37.0%, respectively. There were a small number of whiteflies in the three test sites in Luanchuan, and the corresponding seed potato infection rate was low or non-toxic; there was no whitefly in the test sites in Yulin and Yinchuan, and the corresponding seed potato SPCSV infection rate was 0 (see Table 2).

[0034] Among the five planting sites in 2021, the average incidence of whiteflies in the Yanjin test site was the highest, at 525.6 heads / yellow board, and the corresponding seed potato SPCSV virus rate was the highest, at 49.0%; whiteflies occurred in the two test sites of Jiaozuo and Shijiazhuang, and their corresponding seed potatoes showed a certain virus rate; only a small number of whiteflies occurred in the two test sites of Luoyang Luanchuan, and the corresponding seed potato virus rate was relatively low (see Table 3).

[0035] The results of field trials in 2020-2021 showed that the occurrence of whiteflies in sweet potato fields was closely related to the virus infection rate of seed potatoes, and the occurrence of whiteflies was the main factor affecting the virus infection rate of sweet potato seed potatoes.

[0036] Table 2 Relationship between the occurrence of whiteflies in sweet potato fields and the virus infection rate in seed potatoes in 2020

[0037]

[0038] Table 3 Relationship between the occurrence of whiteflies in sweet potato fields and the virus infection rate in seed potatoes in 2021

[0039] Test site Occurrence amount of Bemisia tabaci (heads / yellow sticky trap) Virus-carrying rate of seed potatoes (%) Yanjin (N35°15′56″ E114°11′57″) 525.6 49.0 Luanchuan 1 (N33°46'52" E111°45'31") 18.8 0 Luanchuan 2 (N33°46'12" E111°35'24") 14.4 1.0 Jiaozuo (N35°25'15" E114°20'51") 553 17.0 Shijiazhuang (N37°30'36" E114°19'12") 363 15.0

[0040] Example 3. Comparison of the multiplication factors of the spring sowing and summer harvesting propagation mode and the direct cutting propagation mode of virus-free shoot tips

[0041] In mid-October 2023, 5 kg of virus-free seed potatoes of "Shangshu 19" harvested in the spring sowing and summer harvesting mode at the end of July of the current year were taken for seedling raising in the greenhouse. After the emergence of seedlings, the upper 4 leaf nodes of the potato seedlings were cut and cuttings (2 nodes underground and 2 nodes above the ground) were carried out in the greenhouse for propagation. Every 30 days, the seedlings grown from the seed potatoes and their propagated seedlings were cut, and continuous propagation was carried out in the greenhouse. The number of established seedlings (4 - 5 leaf nodes) was counted at the beginning of June 2024.

[0042] At the same time, a control experiment was carried out. The virus-free shoot tips of "Shangshu 19" were directly planted in the greenhouse for propagation. About 100 seedlings emerged from the first crop of 5 kg of seed potatoes. The propagation method and the statistics of the number of established seedlings were the same as those for virus-free seed potato seedling raising.

[0043] The results showed that about 25,600 potato seedlings were obtained by propagating with spring-sown and summer-harvested seed potatoes, and about 10,000 potato seedlings were obtained by directly planting and propagating virus-free shoot tips. It can be seen that the potato seedlings obtained by propagating with seed potatoes are 2.56 times that of propagating with shoot tips.

[0044] Example 4. Comparison of the virus-carrying rates of sweet potato tubers between the spring sowing and summer harvesting mode of the present invention and the traditional summer sowing and autumn harvesting mode

[0045] On July 15 and October 25, 2024, sweet potato tubers harvested at multiple randomly selected locations in Xiangfu District, Kaifeng City were taken, and the virus-carrying rate of SPCSV was detected by the conventional RT-PCR method in the laboratory to compare the virus-carrying situations of sweet potato tubers between the spring sowing and summer harvesting mode and the traditional summer sowing and autumn harvesting mode.

[0046] The results are shown in Table 4. In the traditional summer sowing and autumn harvesting mode, sweet potato tubers from 5 randomly selected locations were taken, and the lowest detection rate of SPCSV was 75%, and the detection rate of SPCSV at 3 of the locations was 100%, and the average detection rate of the 5 locations was 93%.

[0047] In the spring sowing and summer harvesting mode, sweet potato tubers from 5 randomly selected locations were taken. The lowest virus-carrying rate of SPCSV was 20% and the highest was 60%. The average virus-carrying rate of the 5 locations was 43%, which was significantly lower than the virus-carrying rate of sweet potato tubers in the summer sowing and autumn harvesting mode.

[0048] The above experiments fully illustrate that the spring sowing and summer harvesting mode of the present invention can effectively reduce the virus-carrying rate of sweet potato seed potatoes.

[0049] Table 4. Comparison of the virus-carrying rates of sweet potato tubers between the spring sowing and summer harvesting mode of the present invention and the traditional summer sowing and autumn harvesting mode

[0050]

Claims

1. A method for effectively reducing the virus rate of sweet potato seed potatoes and increasing the reproduction multiple of healthy seed potato seedlings by changing the planting pattern, characterized in that: By adjusting the seedling planting time and seed potato harvesting time in the sweet potato seed potato breeding field, we can avoid the harm of the virus-transmitting insect whitefly and reduce the risk of seed potato virus infection.

2. The method for effectively reducing the virus rate of sweet potato seed potatoes and increasing the reproduction multiple of healthy seed potato seedlings by changing the planting pattern according to claim 1, characterized in that: The seedling planting time is from late March to early April every year, and the seed potato harvesting time is late July of the same year.

3. The method for effectively reducing the virus rate of sweet potato seed potatoes and increasing the reproduction multiple of healthy seed potato seedlings by changing the planting pattern according to claim 2, characterized in that: The seed potatoes harvested in late July of the current year are stored and raised for seedling propagation in the winter of the current year or the early spring of the following year.

4. The method for effectively reducing the virus rate of sweet potato seed potatoes and increasing the reproduction multiple of healthy seed potato seedlings by changing the planting pattern according to claim 1, characterized in that: The virus that infects the seed potatoes is sweet potato chlorotic stunt virus.

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