Rim Ahmad Al-Abd Al-Hadi
Maize Research Department, Administration of Field Crops Research-General Commission for Scientific Agricultural Research (GCSAR)
Faculty of Agriculture, Damascus University,
This study was conducted in the Maize Research Department during two growing seasons 2008-2009. The main objectives of the present work was to study heterosis and combining ability components of 28 single maize crosses obtained by half diallel cross among eight inbred lines, They were (IL. 375-06) P1, (IL.363-06) P2, (IL.260-06) P3, (IL.459-06) P4, (IL.275-06) P5, (IL.792- 06) P6, (IL.256-06) P7 and (IL.362-06) P8; identify superior parental lines that could be used in hybrid maize breeding programs; and study the phenotypic correlation and path analysis among traits. The data were recorded to evaluate days to silking (days), plant height (cm), ear height (cm), leaf angle (degree), ear length (cm), ear diameter (cm), number of rows per ear, number of grains per row, 100-kernels weight (g), stay green (days), shelling percentage (%), oil, protein, and starch contents of grains (%), grain yield per plant (g) and grain yield per plot (ton/ha-1).
The results of genetic parameters indicated that:
– Mean squares of inbred lines and hybrids were highly significant for all studied traits, indicating the genetic variance among lines. The mean values of grain yield per plot for all hybrids exceeded the variety (Al Bassel-1), while the hybrid (IL.275-06 — IL.362-06) showed positive and insignificant differences relative to check variety (S-4-985) in grain yield per plot.
– The desirable heterosis percentage relative to mid parents and better parent were 149.73 and 143.97% respectively in hybrid (IL.260-06 — IL.459-06) for grain yield per plant. On the other hand, most crosses expressed significant positive heterosis effect relative to check variety (Al-Bassel-1). This heterosis value reached to 64% in the hybrid (IL.275-06 — IL.362-06) which equal 6.5 ton/ha-1, and it showed positive and insignificant heterosis relative to the check variety (S-4-985) this heterosis value was 2.9% which equal 450 kg/ha-1.
– The ratio (ƒ2GCA/ƒ2SCA) showed that non-additive gene action was more important than additive gene action in controlling all studied traits except for days to 50% silking, leaf angle, stay green, shelling percentage, oil and starch contents of grains which showed predominance of additive gene action.
– Many significant positive GCA effects were obtained for all traits, therefore, it could be concluded that the inbred lines (IL.375- 06), (IL.275-06), (IL.362-06) and (IL.459-06) seemed to be the best general combiner for grain yield, while the lines (IL.792-60), (IL.260- 06), (IL.459-06) were the best combiner for oil and protein and starch contents in grains respectively.
– The hybrids (IL.275-06— IL.362-06), (IL.275-06 — IL.363-06), (IL.260-06— IL.363-06), (IL.362-06— IL.792-06), (IL.363-06 — IL.459-06) and (IL.256-06— IL.792- 06) showed the best specific combining ability effects for grain yield per plot, while the hybrids (IL.275-06 — IL.362-06), (IL.260-06 — IL.792-06), (IL.260-06 — IL.362-06) showed the best SCA effects for oil, protein and starch contents in grains respectively.
– The estimation of SCA showed that the best F1 combination is (IL.275-06 — IL.362-06) for oil and protein contents in grains and grain yield per plant and grain yield per plot.
– Correlation coefficients among traits indicated that grain yield was positively and significantly associated with ear length, number of grains per row, ear diameter, plant and ear height, 100- kernels weight, and number of rows per ear, while it revealed significant and negative correlation with protein contents of grains.
– Path analysis showed ear length, ear diameter and ear height had high positive direct and indirect effects on grain yield. Thus these three traits are considered as the most important sources of grain yield variation and its relative important reached to 78.49%.
maize, half diallel cross, combining ability, heterosis, correlation and path coefficient analysis