The nature of gene action lor yield and ,LS components was studied in four
populations of white maize (Zea mays L.). Six populations (PI. PL. F,. F 2. BC 1 and
8C~) of lour promising crosses amor.g five inbred lines for each cross were evaluated
for silking dale. plant height. ear height. number of kernels/row. number of rows/ear,
ear length, ear diameter and grain ylelctJplant through lwo successive seasons These
crosses were S The rssutts obtained revealed the presence 01 highly signlfiC crosses as well as populations wilJ'lln each cross whh respect 10 all tM studied traits.
Furthermore. crosses and populations within crosses inleracted signlllcanUy with
years for all the studied traits. This finding detected that these crosses and tneir
populations gave different performances in diiferent years (or the studied trails. tn
addition. the results sroweo thai the non-additive genetic variance including
dominance play the major (ole in the genetic expression of these traits. Also. the
results Indicated that mOSI of the siuoied uaus wer8 signific.anUy influenced by one 01
more types of epistatic gene effect, which included aodiuve x additive (aa), dominance
x dominance (dd) and additive x dominance (ad) gena effects 8S appeared in Ihe tour
crosses lor yield and other lrails, indicalinO tha role of non- allelIc inleraclion in lJ'le
genetic expression of studied traits. From the previous results, it could be concluded
that the prcducuon 01 hybrids Is the best bretldiflg program (or the improvement of
maize wilh respect to the studied trails.