Breeding method of new watermelon strain with high combining ability
Through hybridization of honey tetraploid and BM-16-4×, combined with multi-generation self-breeding and strict screening, a new high-coordinated watermelon product was obtained, which solved the problems of low parental coordination, single resistance, contradiction between yield and quality, and low seed production efficiency in watermelon breeding, and achieved high yield, high quality, multi-resistance and high-efficiency seed production of watermelon.
Patent Information
- Application Number
- CN202511000805.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-21
- Publication Date
- 2025-08-29
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
There are problems in existing watermelon breeding with low parental coordination, single resistance, contradiction between yield and quality, and low seed production efficiency, especially in the field of high-cooperation parental selection and selection.
Milk tetraploid was used as the parent and BM-16-4× was used for hybrid pollination. Through multi-generation self-transmissiveness, coordination force determination and trait screening, a new high-coordinated watermelon product was obtained. Combined with spatial isolation and bagged isolation planting, the purity of the parent was ensured, and phenotypic identification and comprehensive trait screening were carried out to optimize the seed production process.
It significantly improves the cooperation of watermelons, improves seedless rate and yield, enhances disease resistance and quality, optimizes seed production efficiency, and solves technical problems in traditional watermelon breeding.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of agricultural crop breeding, and in particular to a method for breeding a new watermelon variety with high combining ability. Background Art
[0002] As a globally important economic crop, watermelon's yield and quality directly impact industry profitability and consumer demand. According to the Food and Agriculture Organization of the United Nations (FAO), China accounts for over 40% of both global watermelon planting area and production. Seedless watermelons, due to their ease of consumption, dominate the high-end market. However, current watermelon breeding faces bottlenecks such as a narrow genetic base of parents and the difficulty in aggregating desirable traits. In particular, significant technical shortcomings exist in the selection of highly combining parents.
[0003] The main defects of existing watermelon breeding technology include: low combining ability leading to unstable hybrid vigor, traditional tetraploid watermelon parents generally have low general combining ability effect value and insufficient specific combining ability variance contribution rate; single resistance and multi-resistance breeding are lagging behind, wilt and powdery mildew are the main threats to watermelon production, and most existing varieties are only protected against single diseases; the contradiction between yield and quality is prominent, high-sugar varieties are often accompanied by low yield, while high-yield varieties have low sugar content; storage and transportation resistance and adaptability are insufficient; backward seed production technology restricts industry expansion, the seed production yield of existing tetraploid parents is generally <12kg / mu, and the seeds are poorly plump, and the production cost of triploid seeds remains high. Summary of the Invention
[0004] In view of this, the purpose of the present invention is to provide a method for breeding a new watermelon variety with high combining ability, so as to overcome the defects of existing watermelon parents with low combining ability, single resistance, contradiction between yield and quality, and low seed production efficiency.
[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:
[0006] A method for breeding a new watermelon strain with high combining ability comprises the following steps:
[0007] The tetraploid honeydew melon was used as the female parent and BM-16-4× was used as the male parent for cross-pollination to obtain the hybrid F1; the F1 was subjected to multiple generations of self-pollination, combining ability determination and trait screening to obtain a new watermelon variety with high combining ability; wherein, the BM-16-4× was a tetraploid strain induced by the homozygous inbred line BM-16.
[0008] Preferably, the induction method of BM-16-4× comprises: soaking BM-16 seeds in a colchicine solution, cultivating seedlings, and then screening tetraploid plants through morphological initial screening and chromosome identification; self-pollinating the tetraploid plants to obtain seeds, and re-checking the ploidy to ensure stability after planting, which serves as the male parent.
[0009] Preferably, the tetraploid honey bee is planted through spatial isolation or bag isolation, and self-pollination is used to preserve seeds to ensure the purity of the female parent.
[0010] Preferably, the hybrid F1 is planted for phenotypic identification, the whole growth period and fruit ripening period are measured, the fruit shape, skin color and flesh color are observed, the single fruit weight and central sugar content are measured, the female flower density and fruit setting rate are counted, and excellent individual plants are screened.
[0011] More preferably, the indicators for phenotypic identification include: a full growth period of 90 to 110 days, a fruit ripening period of 28 to 37 days, spherical or round fruit, black skin or green with wide dark green stripes, obvious wax powder, less than 5% deformed fruit, bright red or scarlet flesh, central soluble solids content ≥11.5%, sugar content near the skin ≥8%, single melon weight 4 to 6 kg, 1.5 to 2 fruits per plant, ≤10 nodes for female flower attachment, ≤5 nodes for consecutive fruit setting intervals, fruit setting rate ≥70%, and fruit-setting rate <10% per plant.
[0012] More preferably, the method further includes conducting a preliminary screening of the combining ability of the hybrid F1, selecting 5 to 10 F1 plants with excellent phenotypic identification, hybridizing them with known high combining ability diploid watermelons to obtain triploid hybrids to be tested, planting and observing seedlessness and comprehensive traits, and subsequently self-pollinating the corresponding parent F1 of the excellent triploid hybrids.
[0013] More preferably, the indicators of seedlessness and comprehensive traits include: the number of normally developed seeds in a single melon ≤ 5, seedless rate ≥ 95%, central soluble solids content ≥ 11.0%, sugar content near the skin ≥ 8.0%, single melon weight ≥ 5.0 kg, number of fruits per plant 1.2 to 1.8, fruit development period 28 to 35 days, full growth period 90 to 105 days, wilt incidence ≤ 10%, powdery mildew disease index ≤ 15, no mildew on the peel and no deterioration of the flesh after 20 days of storage at room temperature, and hardness retention rate ≥ 80%.
[0014] Preferably, the hybrid F1 is self-pollinated to obtain the F2 generation, and the F2 generation population is planted, and individual plants with high combining ability are screened through population separation combined with combining ability determination, including: identification of resistance to wilt and powdery mildew, and at the same time, an incomplete diallel hybridization design is adopted, with the candidate strain as the female parent and hybridized with 2 to 3 diploid male parents, the seedless rate, sugar content and yield of the triploid combination are determined, and individual plants with high general combining ability are screened.
[0015] More preferably, the indicators for the determination of the population segregation combined with combining ability include: wilt disease incidence ≤5%, powdery mildew disease index ≤10, general combining ability effect value ≥1.2, special combining ability variance contribution rate ≥30%, coefficient of variation of fruit traits within the strain ≤10%, chromosome number 4n=44; seedless rate of triploid combination ≥97%, central sugar ≥11.5%, single melon weight ≥5.5kg, and 3 to 5 days earlier than the parents.
[0016] More preferably, the screened high-combining ability individual plants are continuously self-pollinated to obtain the F3 generation, and the F3 strains are planted for comparative testing, and the honey tetraploid is set as a control with BM-16-4×, and the coefficient of variation of traits, peel hardness and storage and transportation resistance are measured, and the resistance stability is re-screened; the indicators include: the coefficient of variation of fruit shape, skin color and flesh color among individual plants in the strain is ≤5%, and the coefficient of variation of central sugar content is ≤3%; after 25 days of storage at room temperature, the peel hardness retention rate is ≥85%, and the soluble solids content of the flesh decreases ≤1.0%; the natural incidence rates of wilt and powdery mildew in the field are both ≤5%, and the disease index identified by artificial inoculation is ≤8; when hybridized with the main plant diploid male parent, the GCA effect value of the triploid combination yield is ≥1.5, the seedless rate is ≥98%, and the fruit commercial rate is ≥90%.
[0017] Compared with the prior art, the present invention has the following beneficial effects:
[0018] The present invention provides a method for breeding a new watermelon variety with high combining ability. The bred new watermelon variety with high combining ability, MiBM-4X, is:
[0019] (1) Significantly improved combining ability. The general combining ability (GCA) effect value reached 1.5-1.8. After hybridization with the diploid male parent, the seedless rate of triploid seedless watermelons remained stable at over 98%, and the weight of each watermelon was 5.5-6.0 kg, a 15%-20% increase in yield compared to the control. The specific combining ability (SCA) variance contribution rate was ≥30%, solving the problem of "unstable compatibility" in traditional hybrid combinations.
[0020] (2) Aggregation of multiple resistance traits. Integrating wilt and powdery mildew resistance genes results in a wilt disease incidence rate of ≤5%, a powdery mildew disease index of ≤8, and a 60% reduction in the incidence rate in naturally diseased areas compared to the main cultivated varieties.
[0021] (3) Cracking resistance is significantly enhanced, and quality and yield are synergistically improved. The soluble solids content in the fruit center is 12.0% to 12.8%, the sugar content near the skin is ≥8.8%, the single fruit weighs 4.8 to 5.8 kg, and the commercial fruit rate is ≥90%, solving the industry problem of "high sugar but low yield". It is also precocious, with a full growth period of 100 to 105 days, 5 to 10 days shorter than that of the tetraploid honey fruit.
[0022] (4) Storage and transportation resistance and adaptability are optimized, and seed production efficiency is improved. After 25 days of storage at room temperature, the hardness retention rate is ≥85%, and the sugar content decreases ≤1.0%, making it suitable for long-distance transportation. It has strong adaptability across ecological zones and has shown stable yields in production areas such as North China, Northwest China, and South China. The seed production yield reaches 15kg / mu, which is a significant 20% increase compared to the traditional tetraploid parent. DETAILED DESCRIPTION
[0023] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0024] Example 1
[0025] The whole process of breeding the new high-combining-ability watermelon variety "MiBM-4X"
[0026] 1. Parent material preparation and tetraploid induction (first year)
[0027] (1) Induction of BM-16 tetraploid (BM-16-4×)
[0028] Seed treatment: 100 plump BM-16 seeds were selected and soaked in 0.2% colchicine solution (pH 7.0) at room temperature in the dark for 24 hours, with shaking every 6 hours. After treatment, the seeds were rinsed with distilled water for 3 times.
[0029] Seedling cultivation: sow the treated seeds in a 50-hole seedling tray (the substrate is peat: vermiculite = 2:1), cover with mulch to maintain a constant temperature of 28°C, shade and germinate for 48 hours, and move to a net room (20-mesh insect-proof net) after emergence. The daytime temperature is 25-30°C and the night temperature is 18-20°C.
[0030] Tetraploid screening:
[0031] Morphological screening: Observe at the cotyledon stage and select seedlings with leaf thickness 30% thicker than that of diploids and dark green leaf color. A total of 30 plants were screened.
[0032] Chromosome identification: Root tips of seedlings (5 mm below the growth point) were pretreated with 0.002 M 8-hydroxyquinoline for 2 h, fixed in Carnoy's fixative (methanol:glacial acetic acid = 3:1) for 24 h, and sliced. The chromosome number was observed under a 1000x optical microscope. 22 plants with 4n = 44 were confirmed.
[0033] Homozygous lines were obtained by self-pollinating 22 tetraploid plants by isolating them individually (in a net-bagging chamber), and harvesting the seeds, which were numbered BM-16-4×-1 to BM-16-4×-22.
[0034] (2) Tetraploid reproduction of honey bees
[0035] 50 tetraploid parents of Mimei were planted, separated by 800 meters, bagged and self-pollinated during the flowering period, with one fruit left on each plant. After maturity, seeds were taken from individual fruits, mixed and stored in a desiccator (humidity ≤ 40%).
[0036] 2. Hybridization Creation and F1 Representative Phenotype Screening (Second Year)
[0037] (1) Hybridization design
[0038] Planting of parents: 30 plants of the honey tetraploid (female parent) and 10 plants each of BM-16-4×-1 to BM-16-4×-22 were sown in the greenhouse in early March, with a plant spacing of 0.8m×2.5m;
[0039] Pollination procedure: One day before the female flowers of the female parent open, use a parchment bag (5 cm in diameter, 10 cm in length). Collect the newly opened male flowers of the male parent, remove the petals, and evenly apply pollen to the female parent's stigma (use 2 to 3 male flowers per stigma). Put the bag in the bag and hang a label (record the hybridization date and male parent number);
[0040] Seed harvesting: After the hybrid fruits (maturity period of 37 days) were harvested, seeds were collected from individual melons, washed and dried, and a total of 22 F1 combinations were obtained, including "Mimei × BM-16-4 × -1" to "Mimei × BM-16-4 × -22", with about 50 seeds in each combination.
[0041] (2) Identification of F1 representative phenotypes
[0042] Planting plan: 50 plants were sown per F1 combination with 3 replicates in a randomized block design. The controls were the honey tetraploid and BM-16-4×-1.
[0043] Phenotypic screening indicators:
[0044] The whole growth period is 90 to 110 days, and the fruit ripening period is 28 to 37 days. The fruit is spherical or round, with black skin or green with wide dark green stripes, obvious wax powder, and deformed fruit less than 5%. The flesh color is bright red or bright red, the soluble solids content in the center is ≥11.5%, the sugar content near the skin is ≥8%, the weight of a single fruit is 4 to 6 kg, the number of fruits per plant is 1.5 to 2, the number of nodes where the female flowers are borne is ≤10, the interval between consecutive fruit setting is ≤5 nodes, the fruit setting rate is ≥70%, and the fruit-setting rate is <10% per plant.
[0045] Screening of excellent individual plants: 5 F1 individual plants with the best overall performance were selected from 22 combinations (numbered F1-1 to F1-5).
[0046] 3. Initial screening of combining ability and separation of F2 generation (third year)
[0047] (1) Triploid combining ability test
[0048] Hybrid combination: F1-1 to F1-5 are used as female parents and hybridized with the diploid male parent "Jingxin No. 1". Ten female flowers are pollinated in each combination to obtain triploid seeds.
[0049] Planting and testing: Plant 100 triploid seeds of each species and test:
[0050] The number of normally developed seeds in a single melon is ≤ 5, the seedless rate is ≥ 95%, the soluble solids content in the center is ≥ 11.0%, the sugar content near the skin is ≥ 8.0%, the weight of a single melon is ≥ 5.0 kg, the number of fruits per plant is 1.2 to 1.8, the fruit development period is 28 to 35 days, the full growth period is 90 to 105 days, the incidence of wilt is ≤ 10%, the powdery mildew disease index is ≤ 15, the fruit skin is not moldy and the flesh is not deteriorated after 20 days of storage at room temperature, and the hardness retention rate is ≥ 80%;
[0051] Screening results: The triploid combinations corresponding to F1-3 and F1-5 performed best, and these two F1 plants were selected for self-pollination.
[0052] (2) Construction of F2 generation population
[0053] 250 plants of each F1-3 and F1-5 self-pollinated seeds were planted, for a total of 500 plants, with three replicates, and segregation traits were observed in the field.
[0054] 4. F2 generation combining ability determination and F3 generation screening (fourth year)
[0055] (1) F2 generation single plant selection
[0056] Resistance identification: Inoculate 1×10 5 CFU / mL wilt spore solution was used to screen 40 individual plants with an incidence rate of ≤5%; 1×10 6 spores / mL powdery mildew spore solution, 28 individual plants with disease index ≤ 10 were screened;
[0057] Ploidy re-examination: stem tip cells were collected from 28 candidate plants and flow cytometry was used to confirm that 4n=44.
[0058] (2) Compatibility determination (NCⅡ design)
[0059] Hybrid combinations: 56 triploid combinations were prepared using 28 candidate strains as female parents and "Jingxin No. 1" and "8424" as male parents;
[0060] Index evaluation: Plant 50 plants of each combination and calculate the general combining ability (GCA):
[0061] There were 12 lines with a yield GCA ≥ 1.2;
[0062] There were 8 lines with a seedless rate GCA ≥ 1.2;
[0063] Preferred individual plants: 5 individual plants (numbered F2-1 to F2-5) with GCA effect value ≥1.2 and SCA variance contribution rate ≥30% were screened.
[0064] (3) Comparison of F3 strains
[0065] Each F2 plant was self-pollinated to obtain F3 seeds, and 30 F3 plants of each line were planted with three replicates. The controls were honey tetraploid and BM-16-4×-1.
[0066] Stability indicators:
[0067] The coefficient of variation in fruit shape, skin color, and flesh color among individual plants within the strain was ≤5%, and the coefficient of variation in central sugar content was ≤3%. After 25 days of storage at room temperature, the peel firmness retention rate was ≥85%, and the pulp soluble solids content decreased by ≤1.0%. The natural incidence of wilt and powdery mildew in the field was ≤5%, and the disease index determined by artificial inoculation was ≤8. When hybridized with the main diploid male parent, the triploid combination had a yield GCA effect value of ≥1.5, a seedless rate of ≥98%, and a commercial fruit rate of ≥90%. The F2-3 strain was ultimately selected as the target strain and named "MiBM-4X."
[0068] V. Regional Trial and Production Demonstration (Fifth Year)
[0069] (1) Multi-point test
[0070] Three test sites were set up in Northwest China (Zhongwei), Northwest China (Yinchuan), and South China (Sanya), with 200 plants of "Mi BM-4X" planted at each site;
[0071] The adaptability data is shown in Table 1:
[0072] Table 1 Performance of “MiBM-4X” multi-site test traits
[0073]
[0074] (2) Production Demonstration
[0075] In the main production area (Yinchuan, Ningxia), 2 mu was planted, and diploid pollination plants ("Zhengkang No. 3") were configured at a ratio of 4:1. The yield per mu was 3,500 kg, the seedless rate was 98%, and the commercial fruit rate was 92%.
[0076] 6. Variety Characteristics and Application
[0077] (1) Breed characteristics
[0078] Ploidy: tetraploid (4n=44);
[0079] Maturity: Medium to late maturity, the whole growth period is 100 to 105 days, and the fruit maturity period is 32 to 35 days;
[0080] Quality: core sugar 12.0% to 12.5%, peel hardness 15N, no deterioration after 25 days of storage at room temperature;
[0081] Resistance: Fusarium wilt incidence ≤5%, powdery mildew disease index ≤8.
[0082] (2) Seed production application
[0083] It is used as the female parent for hybridization with the diploid male parent to produce triploid seedless watermelon seeds, with a seed yield of 15kg per mu, a seedless rate of triploid fruits ≥98%, and a single watermelon weight of 5.5-6.0kg.
[0084] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.
Claims
1. A method for breeding a new watermelon strain with high combining ability, characterized in that: The following steps are involved: The tetraploid honeydew melon was used as the female parent and BM-16-4× was used as the male parent for cross-pollination to obtain the hybrid F1; the F1 was subjected to multiple generations of self-pollination, combining ability determination and trait screening to obtain a new watermelon variety with high combining ability; wherein, the BM-16-4× was a tetraploid strain induced by the homozygous inbred line BM-16.
2. The breeding method according to claim 1, characterized in that: The induction method of BM-16-4× comprises: soaking BM-16 seeds in a colchicine solution, cultivating seedlings, and then screening tetraploid plants through morphological initial screening and chromosome identification; self-pollinating the tetraploid plants to obtain seeds, and re-checking the ploidy to ensure stability after planting, which are used as the male parent.
3. The breeding method according to claim 1, characterized in that: The tetraploid honey bee is planted through spatial isolation or bag isolation, and self-pollination is performed to preserve seeds, thereby ensuring the purity of the female parent.
4. The breeding method according to claim 1, characterized in that: The hybrid F1 is planted for phenotypic identification, the whole growth period and fruit maturity period are measured, the fruit shape, skin color and flesh color are observed, the single fruit weight and the central sugar content are measured, the female flower density and the fruit setting rate are counted, and excellent individual plants are selected.
5. The breeding method according to claim 4, characterized in that: The indicators for phenotypic identification include: a full growth period of 90 to 110 days, a fruit ripening period of 28 to 37 days, spherical or round fruits, black skin or green skin with wide dark green stripes, obvious wax powder, less than 5% deformed fruits, bright red or scarlet flesh, soluble solids content in the center ≥11.5%, sugar content near the skin ≥8%, single fruit weight 4 to 6 kg, 1.5 to 2 fruits per plant, ≤10 nodes for female flower attachment, ≤5 nodes for consecutive fruit setting intervals, fruit setting rate ≥70%, and fruit-setting rate <10% per plant.
6. The breeding method according to claim 4, characterized in that: The method also includes preliminary screening of the combining ability of the hybrid F1, selecting 5 to 10 F1 plants with excellent phenotypic identification, hybridizing them with known high-combining ability diploid watermelons to obtain triploid hybrids to be tested, planting and observing seedlessness and comprehensive traits, and subsequently self-pollinating the corresponding parent F1 of the excellent triploid hybrids.
7. The breeding method according to claim 6, characterized in that: The indicators of seedlessness and comprehensive traits include: the number of normally developed seeds in a single melon is ≤5, the seedless rate is ≥95%, the soluble solid content in the center is ≥11.0%, the sugar content near the skin is ≥8.0%, the weight of a single melon is ≥5.0kg, the number of fruits per plant is 1.2 to 1.8, the fruit development period is 28 to 35 days, the whole growth period is 90 to 105 days, the incidence of wilt disease is ≤10%, the powdery mildew disease index is ≤15, the peel is not moldy and the flesh is not deteriorated after being stored at room temperature for 20 days, and the hardness retention rate is ≥80%.
8. The breeding method according to claim 1, characterized in that: The hybrid F1 is self-pollinated to obtain the F2 generation, and the F2 generation population is planted. Individual plants with high combining ability are screened through population separation combined with combining ability determination, including identification of resistance to wilt and powdery mildew. At the same time, an incomplete diallel hybridization design is adopted, in which the candidate strain is used as the female parent and is hybridized with 2 to 3 diploid male parents, and the seedless rate, sugar content and yield of the triploid combination are determined to screen individual plants with high general combining ability.
9. The breeding method according to claim 8, characterized in that: The indicators for the population segregation and combining ability determination include: wilt disease incidence ≤5%, powdery mildew disease index ≤10, general combining ability effect value ≥1.2, special combining ability variance contribution rate ≥30%, fruit trait variation coefficient within the plant line ≤10%, chromosome number 4n=44; triploid combination seedless rate ≥97%, central sugar ≥11.5%, single melon weight ≥5.5kg, and 3 to 5 days earlier than the parents.
10. The breeding method according to claim 8, characterized in that: The selected high combining ability plants were self-pollinated continuously to obtain the F3 generation, and the F3 lines were planted for comparative testing. The honey tetraploid was set as a control and BM-16-4× was used to measure the coefficient of variation of traits, peel hardness and storage and transportation resistance, and the resistance stability was re-screened. The indicators include: the coefficient of variation of fruit shape, skin color, and flesh color among individual plants within the same strain is ≤5%, and the coefficient of variation of central sugar content is ≤3%; After storage at room temperature for 25 days, the peel hardness retention rate is ≥85%, and the soluble solids content in the pulp decreases by ≤1.0%; the natural incidence rates of wilt and powdery mildew in the field are both ≤5%, and the disease index identified by artificial inoculation is ≤8; when hybridized with the main diploid male parent, the GCA effect value of the triploid combination yield is ≥1.5, the seedless rate is ≥98%, and the fruit commercial rate is ≥90%.