The Test of Combining Ability and Heterosis on the Silkworm(Bombyx mori) Breeding

누에 견.사질에 관한 잡종강세 및 조합능력검정

The study was conducted to obtain the genetic information on heterosis and combining ability of the quantitative characters for F1 hybrid breeding in silkworms. Six parental varieties and each set of 30 diallel crosses in F1's were used as materials, and bred on the randomized complete block design with three replications. Fourteen characters were observed with the twenty samples in each tray. The data were analyzed for (1) heterosis and combining ability in F1 hybrid. The heterosis in the weight and the length of cocoon showed positively high at 24.51%, and 23.4%, respectively and the weight of the whole cocoon as well as the weight of the whole cocoon layer showed a siginificant heterosis ranging from 15.56% to 15.71% and from 17.14% to 19.01%, but the fifth and the total instar period showed negative heterosis. It was found that the combination between, C70XRomogua and N9 X Romogua showed highly a negative heterosis on the fifth instar period and for the cocoon weight. The female of N9+Sansuian and the male of Romogua X Sansurian have a high heterosis effect, on the cocoon shell weight, and Sansurian X Romogua(reciprocal) on the length and the weight of cocoon filament with no regard to sexuality. The significant maternal and cytoplasmic effect on heterosis of the cocoon weight and the cocoon shell weight were observed with the combinations, N9 X C5, N63 X C70 and on the length of the cocoon filament with the combinations, Sansurian X N63, Sansurian X C5, Sansurian X C70 and N9 X C70, N63 X C70 on the weight of cocoon filament. As mean squared of GCA, SCA and RCA were significant with these combining ability for all characters resulted from additive and non-additive altogether and there is a significant difference between reciprocals. Sansurian showed a negative GCA effect on the fifth and total larval duration, but the higher positive GCA effects took places with varieties N9 and C5 on the length, width, weight of cocoon, cocoon shell weight, percentage of cocoon shell weight, length and weight of cocoon filament, percentage of raw-silk with no regard to both generations and silkworm sexuality. The values of SCA between the cross combinations varied generation-wise and sex-wise. It was shown that SCA value for the fifth instar period was highly negative for Sansurian X C70, Romogua X C70, Sansurian X C5, Romogua X C5, but it was positive effect on the cocoon weight, cocoon shell weight with N9 X C5, and C70 X Sansurian, on the length of cocoon filament with N9 X C5, Romogua X Sansurian on the weight of cocoon filament between Romogua and N63 and on the percentage of raw-silk between the combination of Sansurian X Romoga.

본 시험은 누에 일대잡종육종에 있어 양질다사량 우량품종을 육성하기 위한 유전적 정보를 얻고자 수행되었다. 공급재료는 특성이 각각 다른 일, 중, 구 3개지역 6개 품종을 정역으로 이면교잡시켜 F1, F2 각각 30조합으로서 실용형질에 대한 육종가를 얻기 위해 교배조합별 잡종강세 및 조합능력의 검정한 결과는 다음과 같았다. 1. 형질들의 잡종강세는 사질형질인 견사량, 견사장에서 각각 24.51% 및 23.43%로 높았고, 견질형질인 전사종 및 사층중은 15.56%~15.71%, 17.14%~19.01%로서 유의한 강세를 보였으나 유충경과일수 등(5령 및 전령)에서는 부의 잡종강세를 나타내어 그 이용이 유의하였다. 2. 교배조합간의 잡종강세는 5령경과일수의 경우 C70 X Romogua, N9 X Romogua 조합이 높은 부의 강세현상을 보여 사육일수가 단축되는 방향으로, 전견중은 N9 X Romogua, N9 X Romogua 조합이 높은 강세현상을 보여 사육일수가 단축되는 방향으로, 전견중은 N9 X Sansurian의 암, Romogua X Sansurian의 수, 견층중은 암수에 관계없이, N9 X Sansurian의 견사장과 견사량에서는 Sansurian X Romogua의 정역간 교잡에서 각각 높았다. 3. 잡종강세의 모본효과는 N9 X C5, N63 X C70이 전견중과 견층중에서, 견사장에서는 Sansurian이 N63, C5 및 C70과 교잡될 때, 또한 견사량에서는 N9 X C70, N63 X C70이 각각 큰 경향이었다. 4. F1의 조합능력에서 분사량은 GCA, SCA 및 RCA의 전형질에서 유의하여 F1의 조합능력은 상가적 효과와 비상가적 효과가 함께 작용하였으나 형질에 따른 정역간 차이도 컸었다. 5. GCA의 효과는 경과일수에서는 Sansurian이 N9, C5가 견질형질(견장, 견폭, 전견중, 전층중 및 견층비율)과 사질형질(견사장, 견자량 및 생사량비율)에서 세대에 관계없이 높은 정의 효과를 나타내었다. 6. F1의 SCA효과에서 5령경과일수는 Sansurian X C70, romogua X C70, Sansurian X C5, Romogua X C5 등 구주종계와 중국종계간의 교잡에서 전견중과 견층중은 N9 X C5, C70 X Sansurian 이 암수에 관계없이, 또한 Rogmogua X Sansurian, N9 X C5가 F1, F2 간에, 견사량은 Romogua X N63 조합에서, 생사량비율은 Sansurian X Romogua 조합에서 각각 높게 평가되었다.