Abstract: 8 different genotype combinations as female parent, with maize haploid inducer JS6-1 as male parent in Changchun, elm and Baicheng 3 kinds of different ecological environment research, the natural doubling rate of haploid induction rate and doubling rate of colchicine treatment. The results show that the difference between different locations and different genotypes of Maize Haploid induction rate, natural doubling rate and chemical double rate significantly, in Changchun haploid induction rate (15.9%), the natural doubling rate (2.6%) and Amiprophosmethyl (APM) herbicide doubling rate (15.6%) was significantly higher than that of Baicheng and Yushu, Changchun more suitable for Maize Haploid inducing and doubling. There were significant differences in the induction rate and doubling rate among different genotypes. The key measures to improve the efficiency of haploid breeding are to select suitable sites and basic materials, and strengthen field management.
Key words: maize; haploid; induction rate; doubling rate; ecological environment.
According to the "national food security and long-term development plan (2008-2020)" planning, the corn will bear factors added 50 billion kg grain of 53%[1]. in maize yield, the contribution of science and technology of fine varieties rate accounted for more than 43%, at the core of the seed industry.
The traditional breeding method requires 6~7 years of breeding excellent inbred lines, and Stock6 hybridization induced into haploid parthenogenetic haploid maize, then double double DH (Double Haploid) breeding, only need 2 years to purification of inbred lines, greatly shorten the breeding period of [2,3].
At present, the bottleneck of DH breeding in maize is the low rate of haploid induction and the formation of double haploid (DH).
The results showed that the induction rate of [4~7] on the same base system was different, and the doubling rate of different base materials was different. However, there are few studies on the different base materials in different ecological conditions, such as the induction rate, natural doubling rate and chemical doubling rate. Therefore, this study was conducted to investigate the induction rate, natural doubling rate and chemical doubling rate of different materials in different ecological environments, and to provide reference for speeding up the breeding process of maize DH.
1 materials and methods.
1.1 test materials.
The experimental materials were provided by the Department of seed science and engineering, Jilin Agricultural University. Maize Haploid inducing line was JS6-1 (Stock6), which was induced by 8 hybrid combinations according to different groups (Table 1). The haploid seeds used in the experiment were induced by the 8 combinations. The seed is divided into two parts, a natural doubling, a doubling of herbicide, insecticide solution configuration: 50 mg/mL APM+2% DMSO+2% Tween 20, bud tip double dose treatment.
1.2 test methods.
The experiment was carried out at the 3 crop breeding bases in Changchun, Yushu and Baicheng, Jilin Agricultural University.
1.2.1 haploid induction and identification.
The basic materials were divided into 3 parts, respectively, in July 2011 in Jilin, Changchun, elm, Baicheng hybrid induction, each material induced by 5 ears, set up a repeat of 3 times. The grain harvest in the haploid identification by hybridization ear: purple purple and yellow endosperm endosperm and scutellum, purple grain tips were heterozygous diploid endosperm and scutellum; purple grain is colorless haploid. Quasi haploid induction rate of [8]= quasi haploid number of grain / grain number * 100%. induced hybridization
Natural 1.2.2 and colchicine chemical double double haploid.
Natural doubling and herbicide APM doubling at 3 sites in May 2012 for induction of haploid. The test set the row spacing of 65 cm, the planting density was 90000 plants /hm2, repeated 3 times. 5~7 of maize leaf stage, by observing the color and the growth of leaf sheath removal pseudo haploid plants, timely cultivation, weeding, irrigation and other fine management.
Natural conditions: double haploid natural growth in the field, when the plant after tasseling, check each plant tassel, ear and anthers exserted Damxung have fine pollination [9] significantly pollen, the pollen and pollination 1 times. The swollen but unable to reveal the anther Pollen Haploid Plant, adopt the method of artificial broken anther makes the pollen powder evenly in the dew, pollination plants filaments.
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Methods: using APM herbicide treatment towel roll method when the bud germination, ca. 1~2 cm with a blade cut top bud coleoptile; at room temperature, will cut off top of coleoptile bud soaked in 50 mg/mL APM+2% DMSO+2% Tween 20 solution, soaked by water flushing shoots 60 min; then in the nursery sand table, when the seedlings grow to 4 leaves when transplanted to the field, observe its pollen plant after tasseling, self pollination and natural doubling treatment.
Self harvest ear, calculate the natural doubling rate of haploid and doubled the rate of chemical. Haploid doubling rate of haploid plant haploid inbred = / total * 100%.
1.2.3 data analysis.
The data processing of the test data was performed by using the statistical software DPS statistical analysis method
2 results and analysis.
The test data of 3 sites were analyzed using the chi square test, the results show that the 3 place haploid inducing rate (x 2=0.48< x 20.05=5.99), the natural doubling rate (x 2=1.2< x 20.05=5.99), chemical double rate (x 2=0.24< x 20.05=5.99) errors are homogeneous, therefore, can be analyzed for more than a year of joint variance test data.
2.1 haploid induction effect analysis.
Haploid induction rate at 3 sites of 2.1.1.
As can be seen from table 2, the average induction rate of quasi haploid in Changchun was the highest in, which was 15.2%, which was significantly higher than that of elm (11.1%) and Baicheng (8.6%).
Haploid induction rate of different basic materials of 2.1.2.
Table 3 shows the different genotypes of F1 induced by the Hybrid Maize Haploid haploid induction rate must exist significant differences, 8 hybrid combinations of quasi haploid average induction rate in 3 locations in J5 * L8 is the highest, is 15.4%; J3 * L6, J1 * L4, respectively, and 12.4% 12%, among the significant differences of J9 * L12; the average induction rate is low, 8.4% J15 * L18; the average induction rate is the lowest, 8.3%.
Table 4 shows the J5 * L8 in 3 locations of quasi average induction rate of haploid were ranked first; J1 * L4 at second in Yushu, Changchun points average induction rate in Baicheng, ranked fourth; J9 * L12 and J15 * L18 in 3 locations of quasi average induction rate of haploid are ranked in 2 place after that ecological and environmental conditions in different maize combination effects of haploid induction rate tended to be the same.
The effects of different ecological environments and different genotype combinations on the induction rate of Maize Haploid were significant.
2.2 haploid natural doubling effect.
Natural doubling rate of 2.2.1 at different sites.
As can be seen from table 5, the natural doubling rate of haploid in was highest in Changchun (2.6%), which was significantly higher than that in Ulmus pumila (1.7%) and Baicheng (1.2%). The natural doubling rate of haploid was significantly higher than that of Baicheng.
Natural doubling rate of 2.2.2 based materials.
As can be seen from table 6, the average natural doubling rate of the 8 combinations of haploid at J5 * L8 is the highest, which is, J3 * L6 and J13 * L16 times, which are respectively 2.9% and; J15 * L18 and J9 * L12 are the lowest, being 0.5% and 0.1%.
Table 7 shows the J5 * L8 natural doubling rate in 3 locations were ranked first, 4.2%, 3.1% and 5.2% respectively; J3 * L6 and J13 * L16 in 3 locations haploid doubling rate were in second, 3; J9 * L12 in Baicheng, Changchun two sites the average haploid the induction rate was eighth; J15 * L18 ranked seventh in Baicheng, Changchun, J11 * L14 in Yushu ranked seventh.
Genotype and the natural conditions during haploid growth had a significant effect on the fertility restoration of haploid fertility, and the natural doubling rate of the different base materials in the 3 sites tended to be consistent.
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2.3 herbicide APM doubling effect.
APM average doubling rate of 2.3.1 in 3 locations.
As can be seen from table 8, the doubling rate of APM in the 3 locations is highest in Changchun (15.6%), elm (No. 13.5%) and Baicheng (12.6%) minimum.
APM average doubling rate of 2.3.2 base materials.
As can be seen from table 9, the average doubling rate of APM in the 8 combinations at the site was J5 * L8 () () and J3 * L6 (J9) and the lowest (L12).
According to table 10, J5 * L8 and J3 * L6 doubled in the first place in the 3 test sites, of which, J1 * L4 was higher in Baicheng and Changchun, but lower in elm; J9 * L12 at the lowest rates in the 3 sites were the lowest in APM. The results showed that the doubling rate of haploid was not only affected by the genotype of the basic material, but also closely related to the environmental conditions.
The genotype of the breeding base material has a great influence on the recovery of chemical fertility of haploid under different ecological environment conditions.
3 conclusions and discussion.
Zhang Ru, a liberal arts [12] research shows that different parent materials based on quasi haploid induction rate and doubling rate have significant difference. In the experiment of maize haploid inducer JS6-1 as male parent and female parent of 8 different materials in Yushu, Baicheng and Changchun induction rate, doubling rate results show that different genotypes of materials based on quasi natural doubling rate of haploid induction rate, and APM double rate differences; hybrid mode J5 * L8 Lancaster * Lancaster in Yushu, Baicheng, Changchun 3 locations - induction rate and doubling rate of haploid were the highest, indicating that Lancaster germplasm is easy to form haploid and double double rate; hybrid model based on the combination of J13 * L16 * Lancaster is modified by modified LancasterDH system, J13 is inbred pedigree selection the L16 DH system, combined with the analysis of variance showed that the induction rate, natural doubling rate and APM J13 * L16 doubling rate around the point value is higher, that based on the DH system with the material group It was easier to induce haploid, and natural and artificial doubling rate was higher.
The research shows that the test in 3 different ecological environment conditions, the same basic material of haploid induced by 3 ecotypes under the condition of the induction rate, natural doubling rate, APM doubling rate exist significant differences, based on homogeneity analysis, 3 samples from the same group. In Changchun, maize haploid induction rate, natural doubling rate and APM doubling rate were significantly higher than those of Ulmus pumila and Baicheng. The natural doubling rate and APM doubling rate of Ulmus pumila were significantly higher than those of Baicheng. Liu Zhizeng [13] and other studies have shown that the recovery of male fertility of the haploid male has a negative (or positive) correlation with the change of the ambient temperature or the temperature of the day and night. The results showed that the efficiency of haploid induction in winter in Hainan was significantly higher than that in Beijing in the summer of [14]. The research section of Minxiao [15] showed that Beijing and Hainan in spring sowing sowing in winter than other locations planting more conducive to Maize Haploid doubling.
The test results show that the induction rate and doubling rate was significantly better than the elm and Baicheng in the spring Changchun quasi haploid. Changchun spring temperature is relatively low, the differentiation process of maize growth in haploid breeding, through the selection of basic materials, suitable for the location and improve the levels of field management can improve the efficiency of haploid breeding.
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