Genetic effects and heritability for early maturity and nonsenescence traits in sorghum (Sorghum bicolor L.)

A study on inheritance of early maturity and nonsenescence in sorghum (Sorghum bicolor L.) was conducted to determine the mode of inheritance for efficient and effective selection of the desired traits. Two high yielding ICRISAT type sorghum varieties (ICSV-107 and ICSV- 219) were crossed with an early maturing local pothwar type sorghum variety (pothwar 3-9). A field trial with eight generations namely P1, P2,F1,F2,BC1,BC2,BC1(S)and BC2(S) for each cross was conducted at two locations that is National Agriculture Research Centre (NARC) Islamabad and Maize & Millet Research institute (MMRI) Yousafwala during summer seasons of 1992 and 1993. Analysis of generation means indicated that additive genetic effects were important for yield per plant, head length, seeds per head, 1000-grain weight, threshing percentage, maturity index, leaves per plant, leaf area of upper six leaves (LAUSL), percent green leaves area per plant fifty days after flowering (% GLA 50DAF) and sugar percentage, in both the crosses. Dominance effects were also important for yield per plant, 1000-grain weight, maturity index and % GLA 50DAF in cross protocol 1 (ICSV 107 X Pothwar 3-9) and yield per plant, maturity index, leaves per plant, LAUSL, % GLA 50DAF and sugar percentage in cross protocol 2 (ICSV 219 X pothwar 3- 9) which indicated that cross protocol 2 (ICSV 219 X pothwar 3-9) was more non-senescent (stay-green). Epistasis was not important for the desired traits in either population. Significant additive effects suggest that effective selection for early maturity, head length, seeds per head, 1000-grains weight and yield, is possible in cross protocol 1 (ICSV 107 X pothwar 3-9) and selection for leaves per plant, LAUSL, %GLA 50DAF and sugar percentage is possible in cross protocol 2 (ICSV 219 X pothwar 3-9). Selection for early maturity would be more effective in later generations. In cross protocol 2 (ICSV 219 X pothwar 3-9) selection for yield could also be practiced in early generations. Narrowness heritability estimates for various components ranged from low to high in both populations. Low heritability for yield suggested that selection in cross protocol 1 (ICSV 107 X Pothwar 3-9) should be practiced in later generations. Low correlation between yield and early maturity in both crosses indicated that selection for early and favourable recombinants could be possible from these crosses.