A half diallcl cross between lo inbred lines of maize (Zea mays L.) was
evaluated under two diufcrcnt sowing dates for ten quantitative characters.
Sowing date, genotypes, parents and hybrids mean squares were significant for all
traits under study. Significant genotypes x sowing date mean squares were
obtained for all traits except ear height, car husk and no. of rows/ear. Significant
interaction between hybrids and sowing dates mean squares were obtained for all
traits except car height, car husk and no. of rows? car. General and specific
combing ability mean squares were significant for all traits. The magnitudes of
the ratios of GCAISCA revealed that the additive and additive x additive types of
gene action were the most important expressions for ear husk, maturity date, no.
of rows/ear, tasseling date and silking date. Plant height, ear height, no. of
grain/row, 100-kernel weight and grain yield/plant showed GCAISCA ratios less
than unity. The mean squares of interaction between sowing dates and both types
of combining ability were significant for tasseling date, silking date, plant height,
no. of grains/row and grain yield/plant. The ratio for GCA x D/GCA was higher
than ratio of SCA x D/SCA for tasseling date, plant height, no. of grains/row, and
grain yield? plant. The parental inbred line no. 4 seemed to be good combiner for;
plant height, car height, no. of grains/row, 100-kernel weight and grain
yield/plant. The parental inbred line no, 10 appeared to be one of the good
combiner for; ear husk, no. of rows? ear, no. of grains/row and grain yield/plant.
The cross P1xP8 had the highest values for both SCA and hcterotic effects
followed by crosses PIXP)O, P4xP5, P6xP5 and P6xP,0 for grain yield. The five
RAPD primers generated 143 scorablc bands across 10 inbred lines. These
primers produced a total of 32 reproducible fragments, from which 26 (73.06)
were polymorphic. The mean of polymorphic bands per pruner was 5.2. The
lowest genetic similarity (0.333) was obtained between the two inbred lines P2
and P,, while, the highest genetic similarity (0.81) was scored between the two
inbred lines P10 and P,. The estimated value for correlation coefficient between
genetic diversity (GD), and each of nican performance and hetcrosis relative to
both checks vanetes and SCA for grain yield? plant were significant (r 0.3 15,
0.332, 0.334, 0.401), respectively. The corrclaiion coefficient between sub
clusterl (inbred lines P1 and P2) and main cluster 2 (inbred lines P,, P8, P,and P,0)
was higher (r 0.56). In the same time the highest values of grain yield and
heterosis were obtained from the crossing between inbred line P, (sub cluster I)
and inbred line P8 (main cluster 2). |
