Analysis On Genetic Variance And Combining Ability Of Oil Fatty Acid Contents In Soybean

The oil fatty acids of soybean mainly consist of saturated fatty acids (palmitic and stearic) and unsaturated fatty acids (oleic, linoleic and linolenic). The character of oil of soybean is relation to the composition and proportion of unsaturated fatty acids in soybean oil. Oleic and linoleic are good for health and are important for avoiding hypertension and heart disease etc. The higher linoleic content is, the higher value of nutrition of oil is. Linolenic is easily to cause the value of nutrition of oil to decline. Because palmitic and stearic are hard to be digested and absorbed, they are harmful to people's health. The strategic of improving oil fatty acids in soybean is to increase linoleic content with decrease linolenic content. The aim of the experiment is to analyze the genetic variation and combing ability of oil fatty acid contents, and the conclusion of the experiment could be as a reference for characters selection of quality breeding of soybean.The two popularized cultivars in Jilin are Jinong No.7 (P1) and Jiunong No.21 (Pa), and three American low-linolenic materials are Century (P3), A5 (P4) and C1640 (P5). The five parents were used as parents to make complete diallel crossing in accordance with the Griffing's method 2. The crosses of P1 x P5, P2 x P5, P3 x P5 and P4 x P5 were backcrossed by C1640- The genetic correlations between oil fatty acids and main agronomic characters, quality traits and components of oil fatty acids were analyzed. At the same time, the path-coefficients of oil fatty acids to SWP (the seeds weight per plant), oil content, 100SW(100 seeds weight) and linolenic content were processed. The heterosis, combining ability and heritability of oil fatty acids were also estimated. The results showed that:(1) The average of oil fatty acid content of hybrid is between averages of two parents. The contents of palmitic, oleic and linoleic are slightly lower than the averages of their parents. Heterosis of mid-parent is in the specific crosses. Stearic and linolenic indicated heterosis of mid-parent in the view of mean of crosses. The result of over-parent heterosis analysis is the same as heterosis of mid-parent.(2) The genetic correlation between 100SW and the contents of palmitic, stearic, oleic and linolenic is positive. The genetic correlation is highly positive between the content of linolenic and 100SW. The genetic correlation is negative between linoleic content and 100SW. The contents of linoleic, linolenic and palmitic can be selectedindirectly by 100SW.(3) Oleic is very stability and highly negative genetic correlation with linoleic and linolenic., We can select indirectly the material with high content of oleic, namely, increasing oleic content and decreasing linolenic content simultaneously by this genetic correlation.(4) The highly negative correlation between linoleic and linolenic accorded with the result of path-coefficient analysis. It is the same as the results of Xu Bao's and Ping Chunzhi' s researches, and it's contrary to the results of many other researches. It's possible for selecting low content of linolenic and maintaining high content of linoleic simultaneously with the negative correlation.(5) The direct path-coefficients of contents of oleic and the linolenic to SWP were 0.8467 and 0.5079 respectively. The genetic correlation coefficients of contents of oleic and linolenic to SWP were 0.4374 and 0.1983 respectively. The result of path-coefficient analysis almost accorded with that of genetic correlation analysis.(6) The direct path-coefficients of oleic and linoleic to 100SW were -1.78 and -1.8855 respectively. The genetic correlation of linoleic content and 100SW was greatly negative. The results of genetic correlation analysis coincide with the results of path-coefficient analysis. The genetic correlation between oleic content and 100SW was positive, and the direct negative effect of oleic content to 100SW was concealed by indirect positive effect through linoleic content to 100SW.(7) The direct effects of the oil fatty acid...