• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.113-115
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• 2004

Six generations (P$_1$, P$_2$, F$_1$, BC$_1$, BC$_2$ and F$_2$) of four bivoltine silkworm crosses (SKAU-R-1 ${\times}$ Yakwei, SKAU-R-6 ${\times}$ Yakwei, CSR$_2$ ${\times}$ CSR$_4$ and SH$_{6}$${\times}$ NB$_4$D$_2$) were evaluated in a completely randomized block design with 5 replications for each treatment. The generation mean 2 in respect of 3 metric traits (single cocoon weight, single shell weight, and shell ratio ％), were subjected to Cavallis joint scaling test. Additive dominance model was found to be adequate in CSR$_2$${\times}$CSR$_4$ and SH$_{6}$${\times}$ NB$_4$D$_2$ for single cocoon weight and shell weight and SKAU-R-6 ${\times}$ Yakwei for shell ratio(％). Whereas, in rest of the crosses epistasis was evident in the traits under investigation. Magnitude of additive gene effect (d) was greater than dominance(h) in SH$_{6}$${\times}$NB$_4$D$_2$ and SKUA-R-6${\times}$Yakwei for shell ratio (％) and in CSR$_2$${\times}$ CSR$_4$ for shell weight. Thus selection for these traits in early segregating generations of these crosses would be effective for obtaining considerable genetic gain. gain.

• Korean Journal of Poultry Science
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• v.12 no.2
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• pp.75-82
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• 1985

This study was carried out to estimate combining abilities and heterosis in White Cornish and White Plymouth Rock. The data were obtained over an 8weeks period from 3rd Oct., 1984 to 28th Nov. 1984 at the Livestock Experiment Station. A total of 810 birds, composed of 369 pure strains, 270 two-way crosses, and 180 fourway crosses were average amount of heterosis expressed as a ratio was 1.63% for livability, 5.47% for body weight at 8 weeks, 5.57% for weight gain from day old to 8 weeks and -5.98% for feed requirement. Specific combining ability were statistically significant for all of the traits examined in this study. Although the general combining ability was not significant for any of the traits, strain A appears to be superior to other strains.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.23 no.2
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• pp.34-39
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• 1978

Partial dominance was exhibited by flowering(heading), panicle length, panicle numbers, $F_1$ag leaf length, 1000 kernel weight in $F_1$ and $F_2$ hybrids by 7 \times 7 and 5 \times 5 diallel crosses. Over dominance was exhibited by culm length, flag leaf width, appearance degree of panicle in $F_1$ generation of the crosses, and also over dominance was exhibited by kernel weight in $F_2$ generation of the crosses.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.25 no.2
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• pp.15-22
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• 1980

Alkali digestion value of rice kernels was increased with delayed planting date and decreased with temperature during ripening. Varietal difference in average digestion value between low and high groups of rice varieties was the greatest under the conditions of 1.4 percent solution of potassium hydroxide, early planting and day/night temperature of 30/22$^{\circ}C$ Segregation ratio of alkali digestion value in $F_2$ generation was varied with crosses showing 3:1 for nine crosses, 1:3 for one cross, 9:7 and 13:3 for two crosses respectively and non-segregation for one cross of 15 crosses between low and high varieties in the digestion value.

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.3
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• pp.295-300
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• 1995

Data from purebred and crossbred cattle involving Holstein and the Local breed in Bangladesh were used to estimate the genetic effects on average daily milk yield and birth weight A total of 877 records on average daily milk yield for 4 types of breed groups and a total of 418 records on birth weight for 5 breed groups were analyzed. Two different methods were applied in this study; the least squares analysis of variance approach and the linear regression approach. Breed group effects were highly significant for both average daily milk yield and birth weight. The result showed that straightbred Holstein produced the highest milk yield and the 7/8 crosses ranked highest in birth weight For the two traits, the additive breed effect was highly significant, whereas the individual heterosis effect was not significant. Furthermore, this study showed a negative maternal heterosis for average daily milk yields and a positive maternal heterosis for birth weight Comparing the breed least squares means obtained from the linear regression approach revealed that straightbred Holstein produced the highest average milk yield and the 3/4 crosses were predicted to have the largest birth weight. It is indicated that the linear regression approach can adequately separate the genetic component of performance, estimate unknown crossbreeding parameters and predict unknown performance of crosses which are not include in the original data.

• Journal of Mushroom
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• v.10 no.3
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• pp.101-108
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• 2012

Pleurotus ostreatus 'Miso' is a mutant strain showing white color in pileus from the known parent strain 'Wonhyeong 1'. Shape and several other characters also vary with culture conditions. Mating experiments were performed to understand interstrain mating relationship using monokaryons of the parent and the mutant strains. All monokaryons were grown from single spores isolated from freshly collected fruit bodies. Pairings were performed in 90 mm petri dishes on PDA. They were allowed to grow at 25 until two fronts of the advancing mycelia met and developed a conspicuous contact zone. The contact zone and the outer edges of paired colonies on each plate were examined for clamp connections. The parent and the mutant resulted in tetrapolar incompatibility in intrastrain crosses. In interstrain crosses, each monokaryotic tester strain of the parent strain was out-crossed to monokaryotic tester strains of the mutant. As a result of these crosses it was found that both strains share the same A and B incompatibility factors yielding 25% compatibility.

• International Journal of Industrial Entomology and Biomaterials
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• v.6 no.2
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• pp.197-202
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• 2003

The hot climatic conditions prevailing particularly in summer are not conducive to rear these high yielding bivoltine hybrids throughout the year, In order to select efficiently the breeds with high temperature tolerance, it is very important to analyze critically the impact of high temperature on many silk yielding attributes of silkworm races. Keeping the above in view, the present study was undertaken to determine the effect of high temperature $(36 {\pm} 1^{\circ}C)$ and high humidity $(80 {\pm} 5% Relative Humidity)$ on the rearing performance of pure races, foundation crosses, single hybrids and double hybrids of bivoltine silkworm, Bombyx mori L. The robust bivoltine breeds, CSR18, CSR19, 8HT and 5HT, eight foundation crosses, eight single hybrids and eight double hybrids involving these breeds were chosen as materials in this study.

• International Journal of Industrial Entomology and Biomaterials
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• v.10 no.1
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• pp.61-64
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• 2005

General and specific combining ability effects of six bivoltine breeds of silkworm (Bombyx mori L.) were evaluated for six quantitative characters through diallel method wherein parents, $F_{1}s$ and reciprocals are involved. The breeds $APS_{11}\;and\;APS_{2}$ were found to be the best general combiners for most of the traits studied. The high estimates of specific combining ability (sca) variance (${\sigma}^{2}s$) compared to general combining ability (gca) variance (${\sigma}^{2}g$) indicated the predominant role of non-additive gene action in the control of all the characters. Positive sca effects for majority of the traits were expressed by the combinations $APS_{13}{\times}APS_6,\;APS_{13}{\times}APS_2,\;APS_{11}{\times}APS_6\;and\;APS_5{\times}APS_2$ out of 15 crosses. Among the 15 reciprocal crosses studied, the combination $APS_8{\times}APS_{13}$ showed positive reciprocal effects for all the six traits. With both the parents $APS_5\;and\;APS_2$ being good general combiners the hybrid $APS_5{\times}APS_2$ showing high sca effects is recommended for commercial use.

• Asian-Australasian Journal of Animal Sciences
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• v.6 no.2
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• pp.219-223
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• 1993

A total of 333 calves were evaluated for carcass quality traits including: dressing percentage (DP), yield grade (YG), marbling score (MS), fat thickness (FT) and percent body fat (PF). Mating types included straightbred Angus (A) and Santa Gertrudis (S), the reciprocal crosses of these two breeds and Gelbvieh (G) ${\times}$ Angus. The year of birth, slaughter group and dam breed were found to have greatly influenced DP. Mating types had no effect on DP. For YG, sire breed, sire within sire breed and slaughter group were important. Crossbreds of A ${\times}$ S had the highest YG followed by A purebreds. Crossbreds of G ${\times}$ A had the lowest YG. Sire breed, dam breed and the slaughter group has significantly affected the MS. Sire breed, sire nested within sire breed and slaughter group were found to have greatly influenced the FT. Sires and dams of A produced the greatest FT while sires of G produced the lowest. Slaughter group 2 (slaughtered at 433 days of age) had a greater FT than group 1 (slaughtered at 393 days of age). For PF, sire breed, sire within sire breed, dam breed and slaughter group had significant effects. A purebreds had the largest PF while S purebreds and G ${\times}$ A crosses had the least.

• International Journal of Industrial Entomology and Biomaterials
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• v.5 no.1
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• pp.23-32
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• 2002

The introduction of hybrid and exploitation of heterosis has played a vital role in Indian sericulture industry, which clearly depicts a quantum jump in silk production during the last four decades. Since, the introduction of heterosis, progress in silkworm breeding has depended on success or failure in identifying better combiners. Systematic procedures developed have enabled the breeders to identify the best combiners by combining ability test, line ${\TIMES}$ tester analysis or $D^2$ analysis for maximum expression of heterosis. The level of heterosis expressed in the crossbreed population is determined by the interaction between genotype and prevailing environmental factors. Except some of the pre and post cocoon parameters, heterosis is invariably higher in single crosses compared to three-way and double crosses. However, during hot and humid season, when rearing of F1 bivoltine hybrid is unsuccessful at field level and indigenous races results in very low and poor quality yield, three-way and double crosses can play an important role as an intermediary technology. The objective of this article is to review briefly the concept and causes of heterosis, utilization of different forms of heterosis in silk production and its significance in silkworm, Bombyx mori breeding.