International Journal of Horticulture 2015, Vol.5, No.17, 1
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7
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Materials and Methods
The genetic materials used for the study consist of 6
parents and 8 crossed seeds, aggregate of 14 entries
generated during 2013 cropping season. These were
evaluated in a Randomized Complete Block Design
(RCBD) in two locations, Yola and Mubi locations 0f
Adamawa State, The crossing nursery was established
in June to October 2013 at the teaching and research
Farm of the Department of Crop Production and
Horticulture Modibbo Adama University of Technology,
Yola. After normal land preparation, 8 beds of 2m x
2m each was made. Each bed was planted with four
stands of testers and 12 stands of lines. Giving a total
of 16 plants per bed. Crosses were made between the
four exotic breeding lines (Roma VF, UC28B
GoldenRoma and RioGrandei) and the two non-
commercially cultivated heat tolerant cultivars as
testers (Cherry and Currant) thereby generating 8
crosses. These crosses were made by emasculating the
flowers of the lines by removal of the anther from the
female plants in the evening. Emasculation involved
selecting of flowers that was just about to show
yellow color, The anther cone was carefully removed
making sure the stigma and style do not break.
Leaving intact the sepals, pistilate and the pedicel
parts. One day before maturation of the anthers,
tomatoes are ready for pollination at this stage. The
resultant 8F
1
s progenies along with six parental
cultivars were evaluated at both Yola and Mubi
locations of Adamawa State during the dry season of
2013/2014 in a Randomized Complete Block Design
(R.C.B.D) with three replications.
Results and Discussion
Mean squares from the general analysis of variance
for 8 characters in tomato combined across locations
are presented in Table 1. The result indicated that,
there was no significant difference among the
locations for all characters measured except for
percentage damaged fruits. Highly significant
difference was observed for all characters among the
entries except for weight of fruits per plant. Similar
results were also observed for parents and for crosses.
The location by entries variance was noticed to be high for
plant height at 60 days after transplanting as well as
percentage damaged fruits, number of flower
cluster and number of days to final harvest. It is also
clear that location by parents interaction was highly
significant in characters such as plant height at 60
days after transplanting, percentage damaged fruit,
number of flower cluster, number of fruits per
plant and number of days to final harvest. With
regards to location by crosses, all characters showed
highly significant differences except for number
of trichome. Similar results were a lso observed for
parents by crosses. The GCA variance were highly
significant in characters such as plant height at 60
days after transplanting, number of leaves at 60 days
after transplanting, number of fruit per plant and
number of flower cluster. However, SCA variance
showed significant differences for all characters
except number of flower cluster, trichome count and
number of days to final harvest. The GCA/SCA
variance ratios were less than unity with respect to
trichome count and number of fruits per plant. While
it was positive and greater or equal to unity for all the
remaining characters. The estimate of general
combining ability effects of parents combined across
locations for all the characters studied as
presented in Table 2 reveals that currant was
the highest general combiner, because it showed
significant positive GCA effects with respect to all the
characters except percentage damaged fruits where
negative values are preferable. Cherry, the second
high general combiner had significant positive GCA
effects in all characters studied except weight of fruits
per plant. This genotype however, recorded negative
GCA effects for percentage damaged fruits. Among
the lines, Roma vf is the best general combiner,
because it recorded positive GCA effects for plant
height, number of leaves at 60 days after transplanting,
number of fruits per plant, number of flower clusters
and high negative GCA effect for number of days to
final harvest which shows earliness. It was closely
followed by UC28B as it has high positive GCA
effects for number of leaves at 60 days after
transplanting, number of fruits per plant and number
of flower clusters, it also recorded high negative GCA
effect with respect to percentage damaged fruits. The
remaining lines are the least general combiners
because they have low GCA effects. The estimates of
higher parents heterosis for agronomic characters in
tomato combined across locations as presented in
Table 3 indicates that Four hybrids expressed positive
higher parents heterotic values for plant height;
Currant x RioGrandei had the highest heterotic value
followed by Currant x UC28B. For weight of fruits
