• Journal of Plant Biology
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• v.5 no.3
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• pp.21-24
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• 1962

Intergeneric crossings between the inbred line of Brassica pekinensis var. Chongbangkokun and inbred line of Raphanus sativus var. Oolsanjaelae were made using Brassica as female plant, and obtained two individuals of intergeneric hybrids. Morphological characters of the two F1 hybrids are mostly intermediate of the two parental species, and their somatic chromosome number is 19. Meiotic behaviors of the parental plants were normal, while those of F1 plants were extremely irregular. The mean pairing frequencies per cell of hybrids are 1.09II＋16.811(examined in May), and 1.76II＋15.47i(examined in June). Majority of the pollen grain of parent species are normal, whereas those of F1's are invariably abortive. No seed setting was obtained in the hybrid plants left in the open field.

• International Journal of Industrial Entomology and Biomaterials
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• v.20 no.2
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• pp.61-67
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• 2010

The bivoltine tropical tasar ecoraces of Antheraea mylitta Drury produces cocoons for seed production under seed crop rearing (July-August with $22{\sim}30^{\circ}C$ temperature and 50~70% relative humidity) and for silk production under commercial crop rearing (September-December with $17{\sim}27^{\circ}C$ temperature and 60~80% relative humidity). To consider the impact of hybrid vigour on egg, larva, cocoon and silk related commercial traits, the $F_1$ hybrids made among Daba, Jata and Raily ecoraces were assessed successively for three years. The hybrid vigour in the $F_1$ hybrid of Daba$\times$Jata ($T_7$) was positive for egg fertility (+23.1%), shell weight (+25.6%), silk yield (+79.0%) and filament length (+68.1%), with filament of high denier (11.98d) and reduced larval span (-7.1%). The Jata$\times$Daba ($T_8$) hybrid has shown negative heterosis in egg fertility (-8.0%) compared to the other F1 hybrids, Daba$\times$Raily ($T_9$) and Raily$\times$Daba ($T_{10}$), when they rise simultaneously during the commercial crop season. The better performance of parental ecoraces ($T_4$ to $T_6$) in their commercial traits during commercial crop over parents of seed crop ($T_1$ to $T_3$) and the superior performance of $F_1$ hybrids ($T_7$ to $T_{10}$) over parents of commercial crop ($T_4$ to $T_6$) during commercial crop season indicates the apparent hybrid vigour in tasar $F_1$ hybrids. As the Daba$\times$Jata ($T_7$) and Jata$\times$Daba ($T_8$) $F_1$ hybrids have shown highest hybrid vigour, their rearing during commercial crop can optimize the silk productivity and commercial sustenance of the tasar silk industry.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.7 no.1
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• pp.145-151
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• 1969

To make clear the species of Korean Asiatic cotton, 21 Asiatic cotton varieties collected from China, Manchuria, Japan and Korea and preserved at suwon Crop Experiment Station were crossed to the tester stocks and cytological studies were made for their $F_1$ pollen mother cells. The results were summarized as follows: 1. In the all $F_1$ hybrids between the 21 collections and G. herbaceum tester stocks always one ring-four association was observed. 2. In the $F_1$ hybrids between additional 5 collections and G. arboreum tester stock ring-four or chain-four was not observed. 3. In the $F_1$ hybrids between G. herbaceum tester stocks and between G. arboreum tester stocks no ring-four or chain-four was observed, while in the $F_1$ hybrids between G. herbaceum tester stock and G. arboreum tester stock always one ring-four was observed. In the $F_1$ hybrids between collections also no ring-four or chain-four was observed. 4. From above results and together with the results reported in previous paper the species of Asiatic collections was inferred to the D.U. Gerstel's G. arboreum and their race was inferred to the J. Hutcinson's G. arboreum L. race sinense.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.12
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• pp.1684-1690
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• 2005

Using mRNA differential display technique, we investigated differential gene expression in hybrids relative to their parents in a diallel cross involving four chicken breeds in order to provide an insight into the molecular basis of heterosis in chicken. The results indicated that there was extensive differential gene expression between chicken F1 hybrids and their parents which was classified into four kinds of patterns as following: (1) bands only detected in hybrid F1; (2) bands only absent in hybrid F1; (3) bands only detected in parent P1 or P2; (4) bands absent in parent P1 or P2. Forty-two differentially expressed cDNAs were cloned and sequenced, and their expression patterns were confirmed by Reverse-Northern dot blot. Sequence analysis and database searches revealed that genes showed differential expression between hybrid and parents were regulatory and functional genes involved in metabolism, mRNA splicing, transcriptional regulation, cell cycles and protein modification. These results indicated that hybridization between two parents can cause changes in expression of a variety of genes. In conclusion, that the altered pattern of gene expression in hybrids may be responsible for heterosis in chickens.

• Journal of Korean Society of Forest Science
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• v.46 no.1
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• pp.53-56
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• 1980

We observed performance of segregation in flower color and type of hybrids which obtained from crossing of intra species in Hibiscus syriacus. Obtained results were followings. 1. The purple flower was dominance to the white one and this was presumed that was owing to cytoplasmic heredity. 2. Single and double petal of flower was presumed that was originated from factors of Ss and dd. 3. There was not variation in flower color and type of $F_1$ hybrid between 4 n and 2 n Hibiscus syriacus. 4. There were many variation of flower color among $F_1$ hybrids which abtained in open pollination of Hibiscus syriacus. 5. We could observe many flowers variegated with red color among $F_1$ hybrids which obtained in crossing between double petal flowers of Hibiscus syriacus.

• Proceedings of the Korean Society of Crop Science Conference
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• 2000.11a
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• pp.200-201
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• 2000

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.4
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• pp.462-465
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• 1987

Three F$_1$ hybrids, Seokwang/Milyang 54, HR1619-6-2-1-2-2/Milyang 54 and 55061/IR19735-5-2-3-2-1, and their parents were inoculated with each of four individual blast races, IC-l3, IH-l, IA-61 and IB-47, and the mixtures of two races, IC-13 and IH-l, IC-13 and IA-61, and IC-13 and IB-47, respectively. The varietal reactions to the tested races showed that two parental varieties of each cross, Seokwang and Milyang 54, HR1619-6-2-1-2-2 and Milyang 54, and 55061 and IR19735-5-2-3-2-1 have different resistance gene(s) respectively. The F 1 hybrids between two cultivars having different resistant genes were resistant to the mixture of two races of which one race was virulent to one parent and avirulent to the other parent respectively, while the parents of these F$_1$s were susceptible. This may suggest that the F$_1$ hybrids have wider spectrum resistance to leaf blast than their parents.

• International Journal of Industrial Entomology and Biomaterials
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• v.47 no.1
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• pp.34-43
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• 2023

The eighteen (18) F₁ hybrid combinations were tested to identify potential combinations adaptable to type 1 climatic conditions in the Philippines. The six (6) bivoltine purelines (DMMMSU 108, DMMMSU 109, DMMMSU 110, DMMMSU 111, DMMMSU 113, and DMMMSU 119); and three (3) multivoltine purelines (DMMMSU 1000, DMMMSU 1007, and DMMMSU 1014), were crossed (multivoltine x bivoltine) in a mating plan. These were arranged in a Completely Randomized Design (CRD), replicated three times, and analyzed using Analysis of Variance (ANOVA). A test of significance was done using ANOVA across years and Tukey's Honest Significant Difference Test (HSD). The multiple trait evaluation index (EI) method was also used in the identification of potential F₁ hybrids. Three major phases were done: (1) parental rearing of multivoltine and bivoltine pure lines for breed multiplication; (2) hybridization process; and (3) evaluation of F₁ hybrids. Rearing evaluations were conducted for three consecutive years. Based from the three evaluations, 10 potential crosses were identified: DMMMSU MV-12, DMMMSU MV-11, DMMMSU MV-13, DMMMSU MV-16, DMMMSU MV-07, DMMMSU MV-14, DMMMSU MV-05, DMMMSU MV-09, DMMMSU MV-03, and DMMSU MV-10. The topmost combinations with the best economic and commercial characters and are consistently adaptable during two (2) cropping seasons were DMMMSU MV-07, DMMMSU MV-12, DMMMSU MV-05, DMMMSU MV-09 and DMMMSU MV-11. These newly-identified F₁ hybrids are considered potential breeds that could improve cocoon production.

• International Journal of Industrial Entomology and Biomaterials
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• v.9 no.1
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• pp.41-46
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• 2004

A breeding programme was initiated by utilizing a robust bivoltine breed CSR$_{18}$ and a polyvoltine breed Cambodge with the main objective of developing robust polyvoltine silkworm breeds/hybrids. At F$_1$ and F$_2$, parthenogenetic development was induced following warm water treatment of eggs at 46$^{\circ}C$ for 18 min followed by two backcrosses with Bl$_{67}$, an evolved polyvoltine breed. The newly developed breed was subjected for hybrid study using eight hybrid combinations in the laboratory at F$_{8}$ generation. F$_1$ hybrids between newly developed breed Bl$_{67}$ (Pg) and promising bivoltine breeds exhibited their superiority by expressing significant hybrid vigour for several economic characters like cocoon yield/10,000 larvae, cocoon weight, cocoon shell weight, cocoon shell ratio and denier. Study on cocoon shape variability revealed that cocoons of all the F$_1$ hybrids except BL$_{67}$ (Pg)${\times}$NB$_4$D$_2$ were found comparatively uniform in shape.pe.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.2
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• pp.49-57
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• 1980

A $F_1$ hybrid out of 143 crosses of rape (Brassica napus) using cytoplasmic-genetic male sterility yielded 5.18 tons per hectare. European and native varieties used, were found out to have 78% and 58% of genes restoring fertility, respectively. The $F_1$ hybrids of three way cross using non-isogenic maintainer showed higher heteroses than those of double cross. To produce F 1 hybrids of three way cross, three stages of crossing operations are needed and seeds produced from about 60 hectares can be covered to 60, 000 hectares.