الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Heterosis and genetic components as well as their interaction with environment for some important traits and genetic diversity by RAPD markers in maize were studied by several investigators. The literature concerning the present study will be presented under the following headings: 2.1- Heterosis. 2.2- Genetic components 2.3- Genetic components x environment interaction. 2.4- Comparison of methods of diallel crosses. 2.5- Genetic diversity by molecular markers. 2.1- Heterosis. Mosa et al. (2004) Top crossed nine yellow maize inbred lines to three testers i.e. L-121, SC Sk-52 and composite-21 during 2001 season. The parents, testers, the twenty-seven top crosses and two checks (SC 155 and TWC 352) were evaluated during the 2002 season at Sakha, Sids and Nubaria locations. They established that best significant heterotic effects were existed in 19 top crosses relative to (mid-parent), 10 top crosses relative to (high-parent), one top cross Sk-7070 X L-121 (24.65%) relative to SC 155 and two top crosses Sk-7070 X L-121 (28.82%) and Sk-7078/2 X L-121 (17.73%) relative to TWC 352 Barakat and Ibrahim (2006) top crossed fifteen yellow maize inbred lines to three promising inbred line testers, i.e. Gm 1002, Gm 1004 and Gm 1021. The 45 top crosses plus three checks (SC 155, SC 3080 and SC 3084) were evaluated at Gemmeiza and Mallawy Agricultural Research Stations in 2005. In the grain yield combined data, they found that, 12 top crosses showed significantly heterotic effects relative to SC 155, 14 top crosses showed significantly heterotic effects relative to SC 3080 and 10 top crosses showed significantly heterotic effects relative to SC 3084. The highest heterotic effects were detected in the cross (Gm 32 X Gm 1004). El-Shenawy (2006) crossed eight yellow maize inbred lines (chosen for general combining ability from top-cross experiments in 2003 season) in diallel cross system without reciprocal in 2004. The obtained crosses and two checks (SC 155 and SC 3084) were evaluated under two locations (Sakha and Sids) in 2005. He concluded that six crosses had negative and significant heterosis compared with the best check SC 155 for earliness. Fifteen and seventeen single crosses for plant and ear height, respectively showed negative and significant heterosis compared with the best check SC 155. Seven crosses revealed positive but not significant heterotic effects compared with the best check SC 3084 for grain yield ard. fed.-1 Nine crosses showed positive and significant heterotic effects compared with the best check SC 3084 for ear diameter. While 6, 16, 16 and 18 single crosses showed desirable significant heterotic effects compared with the best check SC 155 for silking date, plant height, ear height and number of rows ear-1, respectively.