الفهرس 
Experimental schemoOnly 14 pages are availabe for public view
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Abstract
The main objective of the presmt study was to determine heterosis and combining abtlity (g.0.a. and s.c.a.) and theh interaction wlth the change in environmental conditions of ten varieties of mai~e. A aecond target wae to evaluate the teq va r i e t i e s cr- se in order to select the beat use In hybrids and for the planning of the beet method of eelectSon for improvemen$ as well as adapted high yielding syntheGio variet iesl . Ten varieties of maize and their diallel crosaea made in 1984 season were evaluated under four different environments; two plant densities, 20,000 (Dl)and 30,000 (Dp) plants per feddan and each alternated wlth two nitrogen level s 70 kg N (5)an d 140 kg. B (I?*) pep feddan over two years (1985 and 1986) in the fa= of the college of agriculture at Kafr El-Shew, Tanta Unhmaity. The varieties under study consisted of five adapted varieties; Giza-2 & Cabo I, Gemmieza 7421 & Qemmieea 6 and Alex. 4 in addition to five introduced varietiee or synthetic which traced back or thelr parenta to the origin varieties of U.S.A. Mexico and India; Tep. 5 80 Corn Belt & American Early (A.E. 1, Col~poaite (COW 5 ) and C.17. Four environmental conditions designated aa Dl% & DlN2, D2N1 and D2N2 were proposed under which the genotypes would be tested., Each experiment consisted of the 45 varietal CrOaBeB in addition to the ten parent varieties as well as two commercial varieties; Ploneer 514 and D.C. 202 aa controls. The 57 genotypes were tested in each of the four envlzomental conditions 2n two years 1985 and 1986 which comprlse 8 experiments (4 x 2 = 8) 3n a randomized complete block desim experiment, with two replicates. The variations among entries each environment were calculated In both years. The f0ta.u experlmenta over two years were combined In one analysiE1 of between the genotypes and the environmenta or years. Average hsterosis were calculated relative to mid, high and canetant pasent . The varlatlana among cxoetirers were f’brther pa~fi%ior~caidnf o Qhs general a~sd specific combfnhg components aoc0rdbg to GrlSf- 3mg.v a method 4 model I (1956). The data were taken on grain yield (kg./pLot), ailking date, ear height .(cm. ) , number of eare/100 plants , ear length (cm, ) , number o#’ rows/eas,number of kernels/row; and weight of 100 kernels.