ESTIMATION OF SOME PARAMETERS, HETEROSIS AND HERITABILITY FOR YEILD AND MORPHOLOGICAL TRAITS IN INBRED LINE OF MAIZE(Zea mays L) USING LINE X TESTER METHOD

Abstract

The study was conducted at field experiment - College of Agriculture– in Dohuk University during spring and autumn season (2007). Fourteen inbred lines (genotypes) of corn were used for this study, ten genotypes namely (ZP-204, Zp-301, ZP-595, ZP-670, ZP-430, ZP-505, UN- 44652, ZP –735, OH 40, and DK-17) were used as line males and four genotypes (ZP- 197, ZP-607, ZP-707, UN-44052) were used as testers (females), every genotype was planted in row with 400 cm along, 75cm between rows and 25cm between plants. A line x tester method was used which was suggested by (Kempthorne, 1957), for estimation the general combining ability of parent and specific combining ability of their F1 hybrids. Genetic components resulting from additive and non-additive type of gene action were also estimated. Heterosis was measured as a deviation of from the mid-parents. The proportional contribution of lines, testers and line x tester interaction, average degree of dominance, heritability in broad and narrow sense and expected genetic advance were determined. In spring season crossing was done, and in autumn season assessment (54) genotypes (40 F1 + 10Lines + 4 Testers).
The result shows: Significant positive heterosis in F1 generation over mid-parent values in favorable direction was obtained for most studied characters of hybrids also significant negative heterosis in desirable direction was recorded for days to 50% tasseling and days to 50% silking. Heritability in broad sense was high for all studied characters while heritability in narrow sense was high for days to 50% tasseling, plant height and ear height. The value of additive gene effects was more than the value of dominance gene for days to 50% tasseling, plant height, ear height and leaf area, while the value of dominance gene effects was higher than the value of additive gene effects for days to 50% silking and chlorophyll. The average degree of dominance was greater than one for days to 50% tasseling days to 50% silking and chlorophyll.