Generation mean analysis and inbreeding depression in pearl millet [Pennisetum glaucum (L.) R. Br.]
In the present investigation, nature and magnitude of gene action was analyzed in six generations (P1, P2, F1, F2, BC1 and BC2) for grain yield and its attributing characters in four crosses of pearl millet. On the basis of individual scaling test A, B and C and joint scaling test, the additive-dominance model was found to be adequate for description of variation in generation means for number of nodes per plant, number of effective tillers per plant, grain yield per plant and biological yield per plant in all the four crosses, days to flowering in ICMB-04999 x J-2454; days to maturity and earhead length in crosses ICMB-20071 x J-2480 and ICMB-04999 x J-2454; while, test weight in crosses ICMB-20071 x J-2500 and ICMB-20071 x J-2480. For remaining cases, significance of either all or the three or any of the individual scaling tests A, B or C and significant Chi-square values confirming the involvement of digenic interaction parameters in the inheritance of these characters. Looking to the interaction components, all the three or any one or any two interaction parameters were found significant for most of the traits in most of the crosses indicating interaction parameters also played important role in the inheritance of these characters. Study indicated that grain yield per plant and its component characters were mostly governed by additive and non-additive gene effects but the magnitude of dominance effect was higher for almost all the characters. Duplicate type of epistasis played a greater role then complementary epistasis was observed for most of cases. The highest estimate of heterobeltiosis was observed for grain yield per plant in cross 1 (76.45%) followed by biological yield in cross 1 (73.76%), number of effective tillers per plant in cross 1 (40.00%), plant height in cross 1 (26.84%), earhead length in cross 4 (11.43%), test weight in cross 1 (11.23%), days to flowering in cross 2 (-8.37%), earhead girth in cross 4 (8.06%) and days to maturity in cross 2 (-3.42%). Highly significant heterobeltiosis with low inbreeding depression was observed for number of effective tillers per plant, earhead length, grain yield and biological yield in the cross ICMB-94555 x J-2290; ICMB-20071 x J-2500 for grain yield and biological yield; ICMB-20071 x J-2480 for test weight and in ICMB-04999 x J-2454 for earhead girth and biological yield.
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