چكيده لاتين :
COMBINING ABILITY AND TYPE OF GENE ACTION FOR GREEN FODDER YIELD AND ITיS COMPONENTS IN SOME TEOSINTE MAIZE HYBRIDS. ABSTRACT
Although there are many forage crops valid in our country but the forage yield
of maize (Zea mays L.) a fodder crop popular because of its earliness succulence and
high yield. It could be increased if the tillering habit of teosinte (zea mexican)
transferred to maize through hybridization breeding program. In this, investigation
three lines of teosinte, which were derived from selection among segregating
generations of three crosses. The three lines of teosinte were crossed by three
genotypes of maize, inbred line 34 , inbred line 63, from National Maize Research
Program and single cross 30k8 (commercial) to produce nine crosses at Serw
Agricultural Research station in 2007 growing season. The nine crosses and their
parents were evaluated during 2008 and 2009 seasons at Serw Agricultural
Research. The studied traits were number of tillers per plant, number of leaves per
plant, plant height, leaves weight to stems weight ratio, green fodder yield per plant,
dry fodder yield per plant and digestible protein percentage. The data were subjected
to biometrical analyses and the obtained results could be summarized in the following:
Significant mean squares for crosses and tester (maize) for all studied traits
were observed. Mean squares of line (teosinte) is not significant for all studied traits
except for L/S ratio and green fodder yield in the first cut. In addition, mean squares of
lines x testers interactions were significant and highly significant in most occasions for
all studied traits except for number of tillers per plant and L/S ratio. Years, crosses by
years, tester (maize) x years and L x T x Y interaction were significant in most
occasions. There was no specific parents exhibited highest mean through the three
cuts with respect to most of studied traits. However, line-3 of teosinte , was the best
parent for number of tillers per plant , L/S ratio, numbers of leaves per plant , green
fodder yield and dry fodder yield per plant through the three cuts. On the other hand,
the cross L1xT1 followed by L3xT1 were the best combinations for green fodder yield
per plant as a total of three cuts. In general, the over all means of crosses exceeded
their parents except for number of tillers per plant and number of leaves per plant. The
parental inbred lines that exhibited desirable general combining ability (GCA) effects
were L1 for number of leaves per plant, L/S ratio and dry fodder yield per plant. In
addition, L-2 for dry fodder yield per plant and digestible protein and L-3 for dry fodder
yield per plant. Generally, these inbred lines could be recommended for advanced
stage of evaluation by teosinte and teosinte x maize program. Line 34(tester-1) was
good general combiner for green fodder yield per plant, dry fodder yield per plant and
digestible protein percentage while line 63( tester-2) was a good general combiner for
number of tillers per plant, number of leaves per plant, green fodder yield per plant,
dry fodder yield per plant and digestible protein percentage. The highest SCA effects
were observed in the crosses L1xT3, L2xT1, L2xT3 and L3xT1 for dry fodder yield per
plant and L1xT1 and L2xT2 for digestible protein percentage. Estimation of general
combining ability (σ2GCA) for maize (tester) higher in magnitude than those of
(σ2GCA) for teosinte (line) for all studied traits. So that the contribution of maize were
higher than the contribution of teosinte for all studied traits. General combining ability
variance components (σ2GCA) was larger than that of specific combining ability
variance (σ2SCA) for all studied traits indicating that additive genetic variance played
Sakr, H. O.
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the major role than non-additive gene action in the inheritance of these traits. The
variance of general combining ability interaction with years (σ2GCA x Y) was higher
than the variance of specific combining ability interaction with years (σ2SCA x Y) for
most traits these indicating that additive type of gene action was more affected by
environmental conditions than non-additive effects. Significant positive correlations
were observed among all studied traits. Therefore, the selection for one of these traits
will be associated with the improvement of the other traits during the selection
program. In conclusion, from the previous results, it could be recommended that, the
best crosses with highest SCA effects should be used as started materials for
selection breeding program to important fodder yield components.
