Bitter gourd (Momordica charantia L.) is extensively cultivated for its tender fruits owing to its nutritive and medicinal values. In India, a wide range of variability is available in bitter gourd for fruit characters in terms of size, shape, flesh thickness, colour etc. Yield is a complex character influenced by various component characters inherited polygenically and highly subjected to environmental variations. The exploitation of genetic variability of these traits through hybridization and selection is the primary focus of most crop improvement programmes. A good knowledge of genetic systems inheriting the expression of these characters facilitates the choice of the most efficient breeding and selection procedures. In addition to additive and dominance variation, it has been suggested that epistasis may also be involved in the inheritance of many quantitative characters in bitter gourd (Dey et al., 2010). But the information available on non-allelic interactions for quantitative traits in bitter gourd is very limited. Therefore, the present study was undertaken using generation mean analysis to partition the genetic variation into additive, dominance and epistasis which helps in formulating an effective and sound breeding programme.

Results and Discussion

The significance of A, B, C and D scales for different characters of two crosses were presented in Table 1. The A and B scaling tests provide the evidence for the presence of all types of interactions viz., additive×additive [i], additive×dominance [j] and dominance×dominance [l]. the C scaling test provide information about dominance×dominance type of interaction effect whereas D scaling test gave information about presence of additive×additive type of non-allelic interaction effect. Based on the significance of these scaling tests, six parameter model was employed according to Jinks and Jones (1958) to estimate six components (m, d, h, I, j and l) of genetic variation. The results (Table 1) revealed the presence of non-allelic interaction effects in expression of all the traits studied in both the crosses. These results are in comparable with that of Celine and Sirohi (1998) in bitter gourd.

Table 1 Test of significance of A, B, C, and D scales for different characters in bitter gourd

The genetic parameters viz., m, d, h, i, j and l of two crosses were presented in Table 2. Significant positive dominance effect was exhibited by cross IC-044417×IC-045339 while additive and dominance effects were significant and positive (but dominance was in higher magnitude) in cross IC-045339×IC-470560 for vine length. These results indicating the importance of dominance gene effect in expression of this character indicating the possibility of heterosis breeding for the improvement of this parameter in bitter gourd. The interaction effects revealed significantly positive i component in IC-044417×IC-045339 and both i and l in IC-045339×IC-470560.

Table 2 Estimates of components of generation means for different characters in bitter gourd

For number of laterals, both crosses exhibited significant and positive dominance (h) effect and additive×additive (i) interaction effect indicating the role of both dominance and additive gene effects in inheritance of this trait.

Tewari D., Ram H.H., and Jaiswal H.R., 1998, Gene effects for various horticultural traits in bitter gourd (Momordica charantia L.), Vegetable Science, 25(2): 159-161