• Journal of Sericultural and Entomological Science
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• v.37 no.1
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• pp.10-15
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• 1995

Genetic characterization of Sri Lankan silkworm bivoltine population has not been at-tempted so far, since its sporadic introduction of bivoltine strains into the island, starting from the 1950's. Genetic structure of Sri Lankan population of mulberry silkworm Bombyx mori was investigated through estimation of general (GCA) and specific combining ability(SCA) and heritability(${h^2}_B$), on the economic quantitative characters from leading 8 inbreds and their 28 F1's in a half diallel cross, in an attempt to utilize the estimates in determination of future breeding methods and to predict the breeding value over the phenotypic value. It was found that the breeding population of the bivoltine silkworm in Sri Lanka has still maintained considerable amounts of additive gene action as well as nonadditive. For some time in the future, both breeding strategies of "selection without inbreeding" and also "inbreeding followed by crossing" should therefore be effective in genetic improvement of economic characters investigated. In addition, superior combiners in general and in specific F1′s were identified for each of 6 economic characters, to be immediately utilized in selection and also in cross breeding programs in Sri Lanka.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.4
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• pp.296-302
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• 2001

Winter cereals are acclimated during wintering, and thereafter their freezing resistance is increased. In order to analyze inheritance and heritabilities for photoinhibition of photosynthesis by high light intensity under low temperature, and to evaluate the relationship between low temperature-induced photoinhibition and winter survival, 4 parental half diallel crosses were used. The detached leaves of 7-8cm long from plants grown for 35 and 55 days were placed on wet filter paper and placed in trays at 5$^{\circ}C$ cold room with 1,200 $\mu$mol $m^{-2}$ $s^{-1}$ PPFD. Chlorophyll fluorescence was measured with a chlorophyll fluorescence system after dark adaptation for 30 min. The Fv/Fm of 35day old plants was reduced from 0.714 in the control leaves to 0.409 and 0.368 following photoinhibitory treatment of 6h and 8h and the CVs were increased from 0.8% to 22.2-22.3%. The Fv/Fm of 55-day old plants was reduced from 0.775 in the control leaves to 0.485 and 0.439 following photoinhibitory treatment of 10h and 12h, respectively. According to half diallel cross analysis, Reno and Dongbori 1 (highly resistant to photoinhibition) was dominant, but Oweolbori (susceptible to photoinhibition) was recessive, and photoinhibition showed partial dominance with highly additive gene action. Dongbori 1 showed the greatest GCA effects for photoinhibition, and GCA/SCA ratios (8.7-22.3 times) indicated that the additive variance for the character was more important. Winter survival in barley crosses was positively correlated with resistance to photoinhibition and significantly fitted by linear regression ($R^2$=0.751$^{**}$-0.779$^{**}$). The chlorophyll fluorescence measured by Fv/Fm has been found to be highly inheritable and very useful in evaluating relative levels of freezing resistance in barley.ley.

• Journal of Sericultural and Entomological Science
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• v.40 no.2
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• pp.97-104
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• 1998

Mainly due to limited genetic resources available and also urgent need for hybrids suitable to local conditions, conventional theories and regular methods for bivoltine silkworm breeding are not easily applicable in such a tropical country as Sri Lanka which is recently planning to scale-up the silk industry. A simplified but practical methodology was introduced to overcome such constraints. Through application of such modified informal breeding methods, two hybrids named DP0308 and DP0314 were selected for cocoon production. Details of the altered method of germplasm improvement in the silkworm are presented, along with combining ability and heritability estimates for six parental pure lines in a half-diallel cross.

• Korean Journal of Poultry Science
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• v.7 no.2
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• pp.28-36
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• 1980

This study was carried out to estimate combining abilitie or economic traits in layer chickens. The data used in this study were the record of 10 single crosses produced by half diallel cross of 5 lines of Single Comb White Leghorns, such as A, B, C, K and S lines. Total 720 progenies of the crosses were reared at the Poultry Breeding Farm, College of Agriculture, Seoul National University from Feb. 1979 to August, 1980. Combining abilities were estimated by Grilling's mathematical model for the traits; age the first egg, total egg number, egg weight and body weight. The results attained from the studies were summarized as follows; In estimate of combining ability, an age at first egg of BS cross was largely due to significiantly higher general combining ability (G. C. A.) effect of B and S strains than Cand K strains in G. C. A. effect, and to specific combining ability (S. C. A) effect of B and S-trains. AB and BS crosses showed the highest egg Production. AB cross performance was result from high G.C.A. effect of A ana B strains. BS cross performance was result from high G. C. A. effect of B and high S. C. A. effect of BS cross. Specific combining ability effect in egg. weight was not statiscally significiant, but S strain showed high G. C. A. effect. A and B strains in body weight showed significantly low C. C. A. effect. From the above results, BS cross in an age at first egg, AB and BS crosses in egg Production, S strain in egg weight and AB cross in body weight were superior to other strains or crosses.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.51 no.7
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• pp.652-657
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• 2006

Combining ability and heterosis for $F_{1}$ population obtained $5{\times}5$ half diallel cross in sesame were estimated for six quantitative characters. The parental varieties used for diallel cross were Yangbaek and Ansan of normal type, Suwon 177 and 195 of placenta adhesion type (PA) and SIG960320-5-1-1 of indehiscent type (ID). PA and ID type are shattering-resistant sesames and Yangbaek and Ansan are shattering sesames. The high heterosis of $F_{1}$ hybrids was expressed in the number of capsules per plant (NC), grain yield per plant (GY) and number of branches per plant (NB). Shattering.ate (SR) showed high positive heterosis toward increase of seeds shattering in all the combination of $F_{1}$ generation which was presumed because the characters connected with shattering resistance of seeds were governed by recessive gene. At the analysis of combining ability, highly significant general combining ability (GCA) effects were observed on all the characters in $F_{1}$ generation, significant specific combining ability (SCA) effects were observed on the NC, GY and SR. GCA variances were greater than SCA variance, which suggested that additive gene effects were greater than other nonadditive gene effects. Considering the estimated GCA effects, Suwon 195 (PA type) was found to be good parent for SR and GY, SIG960320-5-1-1 (ID type) was poor for GY and plant height. SCA effect for NC was great in Yangbaek/Suwon 195, SCA for GY was great in Ansan/SIG960320-5-1-1, and SCA for decrease of SR was great in Ansan/Suwon177.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.52 no.2
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• pp.198-203
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• 2007

This study was carried out to obtain basic informations for gene action of quantitative characters including shattering resistance. The parental varieties used for $5{\times}5$ half diallel crosses were 'Yangbaek' and 'Ansan' of normal type, 'Suwon177' and 'Suwon195' of placenta adhesion type (PA) and 'SIG960320-5-1-1' of indehiscent type (ID). PA and ID type are shattering-resistant sesames, and Yangbaek and Ansan are shattering sesames. All the characters were sufficient to the assumption for diallel analysis in this experiment. Over dominance was exhibited by the number of capsules per plant, while partial dominance by plant height, capsule setting stem length, grain yield per plant and shattering rate, complete dominance by the number of branches per plant. Additive effect was higher than dominance in shattering rate. High shattering rate was dominant over low shattering rate. Suwon 195, shattering resistant sesame, showed to have the many recessive genes which reduced the shattering rate of sesame seed. Broad sense heritability for all the characters was more than 0.8. Narrow sense heritability for the number of branches per plant, the number of capsules per plant, grain yield per plant and shattering rate was 0.45 to 0.63, and plant height and capsule setting stem length was more than 0.8.

• Journal of the Korean Society of Tobacco Science
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• v.7 no.2
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• pp.111-121
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• 1985

The present study was carried out to obtain some basic informations of the breeding of tobacco varieties. Genetically divergent 8 varieties, 3 flue-cured, 2 burley and 3 sun-cured tobaccos, were used in half diallel cross. In order to analyze the heterosis, combining abilities, modes of inheritance and correlations for some agronomic and chemical characters, 8 parents and 28 $F_2$ were tested. The results obtained were summarized as follows: The percentages of heterosis for yield, stem diameter, internode length and total sugar content in $F_2$ hybrid were positive , where-as those for the other characters were negative. Yield had significant positive genotypic and phenotypic correlations with plant height, days to flower, leaves per plant, leaf length, leaf width and leaf shape index (Leaf length/leaf width). General (GCA) and specific combining abilities (SCA) for all characters of $F_2$ hybrid were significant. In the effect of GCA, yield was greater in combinations of Bulgaria and Xanthi, days to flower and leaves per plant were those of Burley 21 and Va 528, leaf length and width were those of Coker 139, respectively. In the effect of SCA, the major part of characters were greater than those of others in the combinations of Burley 21, Va 528, Hicks.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.6
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• pp.395-401
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• 2002

The combination of early heading time, maturing time and short grain-filling period is very important to develop early varieties in winter barley. The 4 parental half diallel crosses (parents, $F_1$s, $F_2$s) were cultivated at the field. The heading date was from April 3 to 26, maturing date from May 15 to 27 and grain-filling period from 31 days to 42 days, showing that the varietal differences about the 3 traits were remarkable. According to half diallel cross analyses, Dongbori 1 for heading time (late heading) was dominant, but Oweolbori (early heading) was recessive, showing partial dominance with high additive component of genetic variance. Dongbori 1 for maturing time was dominant, but Oweolbori was recessive, showing partial dominance with high additive variance. Reno for grain-filling period (short grain-filling period) was dominant, but Oweolbori (long grain-filling period) was recessive with additive, and partial dominance. There were highly significant mean squares for both GCA and SCA effects on the heading and maturing times, and GCA/SCA ratios for all traits were high, showing the additive gene effects more important. Sacheon 6 and Oweolbori had greater GCA effects for early heading and maturing times, and Dongbori 1 and Reno had greater GCA effects for late times. GCA effects were highly significant in $F_1$ and $F_2$ generations, showing high GCA/SCA ratios (7.02). The heading and maturing times in field were positively correlated with antifreeze proteins concentrations, accumulation, resistance to photoinhibition and winter survival, respectively) but the grain-filling period did negatively correlated with the trails.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.32 no.2
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• pp.208-214
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• 1987

A genetic study on the panicle characters in Oryza sativa was carried out by means of a 5 x 5 diallel cross. The five parental varieties were Raekyung, Yeongnamjosaeng, Nongbaek, Yushin and Honenwase. All characters were correlated positively each other, except number of kernels per primary branch. The number of secondary branches per primary branch.was the most effective factor in determining the number of kernels per panicle, the next being the number of primary branches per panicle. Regression analyses of the data of Vr/Wr indicated the presence of non-allelic gene interactions for all characters. Overdominant characters were the number of kernels per panicle, the number of primary branches per panicle, the number of secondary branches per primary branch, the number of kernels per primary branch and sum of kernels on all the tertiary branches per panicle, suggesting that the characters were more influenced by dominant effect than additive effect. However, the number of kernels per secondary branch was partially dominant where the genetic variation was due more to additive effect than to dominance effect. But after omitting the parent which had non-allelic interaction gene, the characters; the number of kernels per panicle, the number of secondary branches per primary branch, and the number of kernels per secondary branch, were partially dominant. Narrow sense heritabilities(h$^2$ N) in number of kernels per panicle and number of secondary branches were high and moderate, respectively, but those of the rest were lower. Mean squares of GCA and SCA of all characters, except SCA of the number of kernels per secondary branch, were highly significant. Effects of GCA were larger than SCA effects in all characters. Raekyung, Yushin and Nongbaek had highly positive GCA, and the best positive SCA was observed in crosses of Nongbaek x Tongillines (Raekyung, Yushin, and Yeongnamjosaeng) in all characters.

• Journal of the Korean Society of Tobacco Science
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• v.7 no.2
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• pp.99-109
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• 1985

The present studies were carried out to obtain some basic informations of the breeding of tobacco varieties. Genetically divergent 8 varieties, 3 flue-cured, 2 burley and 3 sun-cured tobaccos, were used in half diallel cross. In order to analyze the heterosis, combining abilities, modes of inheritance and correlations for some agronomic and chemical characters, 8 parents and 28 $F_1$ were tested. The results obtained were summarized as follows: The percentages of heterosis for stem diameter, internode length and total sugar content in $F_1$ hybrid were 3.6%, 3.1% and 10.6%, whereas these for days to flower, total alkaloids and leaves per plant were -6.3%, -6.9% and -5.0%, respectively. Yield had significant positive genotypic correlations with plant height, days to flower and leaf length, but negative with internode length and total sugar content. It also had significant prositive phenotypic correlations with plant height, days to flower, leaves per plant, leaf length, leaf width and leaf shape index (Leaf length/leaf width). General (GCA) and specific combining abilities (SCA) for all characters of $F_1$ hybrid were significant. The effects of GCA were positive on yield, plant height, stem diameter, leaves per plant and days to flower of Burley 21. And those were positive on yield, leaf shape index and plant height, but negative on leaves per plant and total nitrogen of Hicks. The effects of SCA for yield and leaves per plant were greater than those of others on the combinations of Coker 139 and Burley type, respectively.