G.B. Pant University of Agriculture & Technology, Pantnagar-263 145, Uttaranchal
Online published on 20 May, 2016.
The fruits of bottle gourd are variable in size and shape. In an experiment, PBOG 13 having round fruit shape was crossed with long fruited PBOG 54. The F1 of PBOG 13 X PBOG 54 showed four kinds of fruit viz., long, oval, pear and round. Segregation for these fruit shape into four classes in the F1 generation confirmed that one of the parents was heterozygous in nature. Significant deviation from 1: 1: 1: 1 in the F1/testcross generation suggested the possibility of linkage between two genes governing the inheritance of fruit shape. The %2 values due to segregation at ‘A ’locus, ‘B ’locus and due to linkage were found highly significant and showed presence of linkage. The recombination value calculated was 0.25. Based on this, the expected frequencies in the F2 generation for long, oval, pear and round fruits were calculated to be 10.2: 13.8: 13.8: 26.2. The observed frequencies of 180 long, 196 oval, 210 pear and 399 round fruited plants in F2 generation gave a good fit to the calculated segregation ratio of 10.2: 13.8: 13.8: 26.2 confirming that the long fruit shape of PBOG 54 was found to be conditioned by two dominant genes (A-B-). The intermediate fruit shape i.e. oval (A-bb) and pear (aa B-) were determined by a combination of one dominant and one recessive gene and round fruit shape of PBOG 13 (aabb) by two recessive genes.
