| Forty-six resistant and susceptible entries screened out from 6724 accessions and five cultivars were examined for their resistance to the natural population of leaf feeding insects in the field by visually estimating the percent defoliation, the result showed that the resistance of soybean to LEI was significantly different among varieties and growth periods. Their existed significant correlations among the five dates of records was significant. Out of 51 soybean germplasm accessions, three genotypes, N3697, N4029-3 and N2 1550, were identified to be highly resistant; five genotypes, N21266, N21249, N4938, N20839, N20793, were identified to be highly susceptil~c. According to tIle 10 day抯 larval weight, larval developmental duration and pupal weight, the 51 accessions were identified for their resistance to cotton worm by utilizing their leaves to feed the larvae of cotton worm. The result indicated that larval weight, length of larval duration and pupal weight were all significantly different among varieties. Larval weight was positively related to pupal weight, larval weight and pupal weight were all negatively related to the length of larval stage. Four genotypes, N2 1266, N4029-3, N2 1550 and N23860, were identified to be highly resistant to cotton worm; Five genotypes, N5052-2, N20839, N8855, N83259 and N23788, were identified to be highly susceptible. These genotypes can be used to do inheritance research. A larval antibiosis screening technique was applied to the study of soybean resistance to cotton worm, five generations (P,, F1, P2, F2, F2.3) from cross between N21297 and Ni 178-2-2 were screened. Mean weight of surviving larvae after I Od of feeding on detached leaves was used as the measure of antibiosis. Analysis of the five generations indicated that the inheritance was controlled by two major genes and polygene mixed inheritance model. The heritability of two major genes was about from 58.62% to 85.32%. The heritability of polygene was 15.01%. The inheritance of resistance to field multiple insects was studied by investigating the percent defoliation of F2 and F2.3 populations. F2 and F2.3 generations came from two crosses, N21297XN1 178-2-2 and N21266XN23860.The result showed that the two parents differed in two major genes and polygene for resistance. Additive gene effect and epistatic gene effect existed. The estimate of heritability for resistance is different between F2 and F23. The heritability of two major genes was about from 74.32% to 82.4 1%. The heritability of polygene was about from 7.36% to 14.25% Sixty-six lines screened out from 4 crosses N21297XN1178-2-2, N119-1XN1178-2-2, 3 N21266XN23860, N21266XN3039 were applied to the breeding for resistant lines. Field resistance and yield were used as two criteria for selection. From resistant lines, five high yield lines were out. The average yield of the five lines is 2 13.43% higher than the average yield of three PIs(P1171451, P1227687, P1229358) and is 23.87% lower than the average of three commercial cultivar. The five lines can be used for the breeding of high yield lines with high resistance to LFI.
|
PDF Full Text Request