• International Journal of Industrial Entomology and Biomaterials
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• v.11 no.2
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• pp.119-124
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• 2005

To determine the level of heterosis, higher cocoon shell weight multivoltine congenic lines (Con. L) and bivoltine syngenic lines (Syn. L) of silkworm were used for crosses. First filial generations $(F_1s)$ expressed heterobeltiotic genetic interaction at significant magnitude (p < 0.01) for single cocoon shell weight (SCSW). The other linked characters viz., single cocoon weight (SCW) and yield by weight per 10, 000 larvae were also significantly higher (p < 0.01) than the better parental lines. All the hybrids showed significant improvement for these aforesaid characters over standard heterosis (Standard check). The reeling parameters viz., filament length, raw silk, neatness, cohesionstrokes etc, also showed improvement among the hybrids than check in congenial environment. Overall results suggested that the cross between congenic and syngenic lines provide better heterosis with good quality silk than conventional hybrids and may be used for commercial exploitation.

• International Journal of Industrial Entomology and Biomaterials
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• v.9 no.1
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• pp.53-58
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• 2004

Studies on heterotic expression in the silk productivity of 66 thermo-tolerant bivoltine hybrids reared under high temperature $(36{\times}1^{\circ}C)$ and low humidity (60${\times}$5%) conditions revealed that manifestation of heterosis was highly significant for majority of the quantitative traits contributing to more cocoon productivity. Observations were made on 8 economically important traits such as fecundity, pupation rate, cocoon yield, cocoon weight, cocoon shell weight, cocoon shell ratio, cocoon filament length and raw silk. Analysis of variance results revealed great deal of variability indicating significant (P < 0.001) variations. Out of 66 hybrids, 7 hybrids exhibited positive heterosis for seven traits and 4 hybrids expressed significant hetero-beltiosis for 6 traits, out of 8 traits evaluated. Based on results, the hybrids ${SR_1} {\times} {SR_5}and {CSR_2} {\times} {SR_5}$ are adjudged as most promising ones and can be exploited commercially in tropical climates to increase the cocoon productivity.

• International Journal of Industrial Entomology and Biomaterials
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• v.7 no.1
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• pp.21-27
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• 2003

Manifestation of heterotic genetic interaction was studied in different hybrids made between multivoltine recurrent backcross (RBL)/congenic lines (Con. L) during unfavourable season when temperature and relative humidity are > $30^{\circ}C$ and 86%, respectively. A few number of silkworm race or strain or breed like Nistari (N ＋ p or Np) can sustain the temperature above 3$0^{\circ}C$ and RH above 86%. The present heterosis study screened a hybrid i.e., CB$_{5}$Lm5RBL1M$_{6}$DPC-LmE$^1$RBL and its reciprocal provided heterobeltiotic effect on survival by number and pupation rate at a magnitude of 20% (p < 0.01) and yield by weight of 10% (p < 0.01). Beside all the hybrids expressed heterosis over check - Nistari (N ＋ p) with better quality silk. Therefore, aforesaid hybrid may be useful for utilization at commercial level during adverse seasons of West Bengal.gal.

• 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.

• International Journal of Industrial Entomology and Biomaterials
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• v.2 no.2
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• pp.133-139
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• 2001

Data from an experiment involving six polyvoltine and three bivoltine silkworm breeds have been analysed to know the level of hybrid rigour and cocoon shape variation in Fl hybrids among silkworm breeds with lows medium and high cocoon weight. Results indicated significantly positive heterosis for several quantitative characters with maximum total heterosis over mid parent value in hybrids between low and medium followed by low and low, medium and medium, low and high and high and low cocoon-weighed breeds, respectively. Study on cocoon shape measurement revelled that among Fl hybrids, cocoons of the three combinations such as GNP ${\times}$ CSR2, GNP ${\times}$ J2 and PM ${\times}$ NB4 D2 were comparatively uniform in their cocoon shape. Importance of this study to know the level of heterosis and cocoon shape variability in different silkworm crosses hale been discussed.

• International Journal of Industrial Entomology and Biomaterials
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• v.13 no.2
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• pp.73-77
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• 2006

Combining ability and hybrid vigour analysis was carried out in hybrids between newly developed non-susceptible lines to BmDNV1 and popular bivoltine breeds for certain quantitative traits viz. Pupation rate, Cocoon yield, Cocoon weight, Cocoon shell weight and Cocoon shell ratio, Survival rate against BmIFV and BmNPV. General combining ability (GCA) effects revealed that among the lines CSR2DR was found good general combiner exhibiting significant GCA effects for six characters, out of seven traits evaluated. Among testers CSR28DR was found as good combiner exhibiting significant GCA effects for six traits. Out of 36 hybrids made between $resistant{\times}resistant,\;resistant{\times}susceptible\;and\;susceptible{\times}susceptible$ breeds, one hybrid $CSR21DR{\times}CSR28DR$ exhibited significant SCA effects for six traits. The selected hybrid $CSR21DR{\times}CSR28DR$ also exhibited significant positive heterosis and heterobeltiosis expressions for maximum traits and could be exploited as commercial silkworm hybrid resistant to important viral diseases.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.6
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• pp.777-782
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• 2002

Reciprocal effects among local breeds and additive and heterosis effects were estimated for total milk production per lactation (TLP), lactation length (LL) and daily milk yield (DMY). Procedures for an optimum crossbreeding system were examined by comparing various crossbred combinations. Three data sets were chosen from the total records collected from 1962 to 1997. Data set I with a total of 5,938 records composed of 9 breed groups for reciprocal crosses, data set II with a total of 6,064 records composed of 5 breed groups for additive and heterosis effects and data set III with a total of 10,319 records composed of 42 breed groups for optimum crossbreeding system were analyzed. The least squares ANOVA was used. The reciprocal crosses between Red Sindhi and the Bangladeshi Local showed significant difference. When the Red Sindhi was used as cow, the cross was superior to the opposite in terms of the three performance traits. The results showed that additive breed effects on both TLP and DMY were positive and highly significant between Bos indicus and Bos taurus, whereas the individual heterosis effects were not significant. In general, any local breeds were improved two to three times by crossing with the Friesian once or twice. However, the effect was reduced when the grading up with the Friesian was repeated more than twice. On the other hand, when the local breed was crossed with the other breeds such as Holstein and Jersey, the improvement of TLP was less. Crossing the F1 cows with the Friesian bull gave further improvement. Almost the same trends were found also for LL and DMY. The local breeds and their crosses are raised mainly for draft animals, then it is recommended that the crossbreds between the local cows and Friesian are used for dairy purposes and more than 75% Friesian blood is used for beef.

• Korean Journal of Agricultural Science
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• v.28 no.1
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• pp.1-7
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• 2001

In this study we evaluated genetic divergence among six Tongil-type rice varieties and assessed the relationship between genetic distance and hybrid performance in all possible non-reciprocal crosses between them. The 15 F1 hybrids along with the six parents were evaluated for eight traits of agronomic importance including yield in a replicated field trial. The six parents were examined for DNA polymorphism using 120 random decamer oligonucleotide primers. A total of 168 polymorphic variants were generated and based on the polymorphism data, genetic distances (GDs) ranged from 0.157 to 0.383. Heterosis was observed in hybrids for most of the traits, and yield exhibited the highest heterosis among the eight traits examined. The correlation values of GDs with F1 performance were not significant. Also the correlations of GDs with midparent and better-parent heterosis were not significant except for spikelets per panicle. Our results have indicated that GDs based on the RAPDs markers may not be useful for predicting heterotic combinations in Tongil-type rice and are supportive of the idea that the level of correlations between hybrid performance and genetic divergence is dependent on the germlplasm employed.

• Proceedings of the Korean Society of Crop Science Conference
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• 1980.05a
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• pp.22.2-22.2
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• 1980

• Proceedings of the Korean Society of Crop Science Conference
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• 1985.10a
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• pp.19-19
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• 1985