Heterosis Analysis And Study On The Relationship Between Heterosis And Genetic Ditance In Bitter Gourd (Momordica Charantica L.)

Identication of combinations that produce hybrids of superior yield is the most important breeding objective. Different blue, white and wild bitter gourd self-lines were used to make a sens of crosses, these crosses were researched for the heterosis appearance of early maturity, yield and fruit quality. Moreover, these crosss were researched for the the relationship between yield heterosis and genetic distances calculated by quantitative characters, protein pattern and ISSR molecular marker. The main results are as follows:Eight inbred lines of green bitter gourd were divided into two groups to make 15 crosses, heterosis of node of 1st female flower and number of female flowers were investigated. The results showed:node of 1st female flower of 6 crosses had negative heterosis over mid-parent,and 13 crosses had negative heterosis superior parent.number of female flower of 5 crosses had positive heterosis over mid-parent,and 4 crosses had positive heterosis superior parent.Six self-lines of bitter gourd were divided into two groups and 9 crosses were made by incomplete diallel cross.Heterosis of 9 characters including yield were researched.Yield heterosis (mean vaule was 27.12%) was the largest.Genetic distance of principal components was calculated by using 11 quantitative characters. Using genetic distance as independent variable and heterosis as dependent variable, we carried out regressing analyses. The results showed that there was a significant linear relationship between genetic distance and yield heterosis and a very significant linear relationship between genetic distance and fruit length heterosis, and their regression equation were Y=7.5718+3.2272X and Y=-5.8529+1.5946X,respectively. Relationships between individual fruit mass and fruit width heterosis and genetic distance weren't found in this study.Heterosis for vitamin C,organic acid ,water content and reducing sugar of fruit were researched by using 8 crosses made by 8 blue self-lines of bitter gourd. Vitamin C content of the fruit generally appeared intermediate between the two parents, 4 crosses had positive heterosis over mid-parent and another 4 crosses had negative heterosis over mid-parent.organic acid content of the fruit of 3 crosses appeared intermediate between the two parents, organic acid content of another 3 crosses were significantly higher than that of the higher parents.The highest heterosis value was 55.70%.Water content of the fruit of 6 crosses appeared intermediate between the two parents,water content of another 2 crosses were higher than that of the higher parents.6 crosses had positive heterosis over mid-parent and another 2 crosses had negative heterosis over mid-parent.Reducing sugar content of the fruit didn't appear intermediate between the two parents, 5 crosses had positive heterosis over mid-parent and another 3 crosses had negative heterosis over mid-parent. The highest heterosis value and the lowest heterosis value were 73.72% and -72.92% respectively.Nine self-lines of bitter gourd were divided into two groups and 18 crosses were made by incomplete diallel cross. Stem width, leaf length, node length, the node of 1st female flower, seeding- flowering days and chilling injury index that involve plant morphology, maturity and ecological adaptation were selected for basic characters. 7 groups of genetic distances which principal component accumulative contribution ratio vary from 70% to 95% are stable when character number which constitute genetic Correlation coefficient matrix was increased from 6 to 12. However. 7 groups of genetic distances which principal component accumulative contribution ratio vary from 95% to 100% are unstable. The biggest Correlation coefficient between genetic distance and heterosis occur when character number is 7 or 8. Then Correlation coefficient become more and more smaller when character number was added. Genetic distances were calculated by using 7 and 8 quantitative characters which principal component accumulative ratio contribution vary from 70% to 85%. Using genetic distance as independent variable and heterosis as dependent variable, we carried out regressing analyses. The results showed that there was a very significant linear relationship between genetic distance and yield heterosis and their regression equation were Y=0.1293+0.0284X and Y=0.1867+0.0324X, respectively.Guangxi wild bitter gourd had small leaves,short node length and small fruits. It was compatible to all cultivars for hybridization. According to the experiment of mixed pollination of two male parentages and observation of botanical Characters, Guangxi wild bitter gourd was identified for subspecies in this study. Green bitter gourd self-breeding line (Q₁) was used as a female parent and wild bitter gourd (P₂) was used as a male parent, the F₁ generation was made. Then F₂, B₁, B₂ were all obtained by self-breeding and backcross. Leaf length, stem width and node length were investigated for genetic effects. The results showed that genetics of stem width and node length are appropriate to additive-dominant model while leaf length is not. Heritabilities in the narrow sense of leaf length, stem width and node length are 0.1694, 0.6418 and 0.3679 respectively. Botanical characters of Guangxi wild bitter gourd were useful for breeding and genetic analysis was important to the utilization of Guangxi wild bitter gourd.Fourteen self-lines including white,green and wild bitter gourd were used to make 14 crosses. Quantitative genetic distance, protein fingerprint genetic distance and ISSR molecular marker genetic distance were researched.At the same time, Relationship between 3 different Genetic Distances and yield Heterosis were researched.Correlation coefficient between quantitative genetic distance and protein fingerprint genetic distance was 0.8340 and Correlation coefficient between quantitative genetic distance and ISSR molecular marker genetic distance was 0.4532. Correlation coefficient between protein diagram genetic distance and ISSR molecular marker genetic distance was 0.5940.There was a very significant linear relationship between quantitative genetic distance and yield heterosis.Also there was a very significant linear relationship between protein fingerprint genetic distance and yield heterosis.However, there was only a significant linear relationship between ISSR molecular marker genetic distance and yield heterosis.