MSc

An experiment in tomato (Lycopersicon esculentum Mill.) was carried
out at the Department of Plant Breeding and Genetics, College of Agriculture,
Vellayani during 1995-96, with the objective of estimating the combining
ability of parents, and gene action involved in the inheritance of different yield
attributes. The study was conducted in a diallel model, using three bacterial
wilt resistant varieties and three popular varieties.
The three bacterial wilt resistant varieties were Sakthi, Arka Alok and
Arka Abha. The three popular varieties were LE 79-5, LE 373 and PKM 1.
These six parental varieties and fifteen hybrids were planted in the field in
Randomised Block Design., with three replications. Observations recorded
were plant height, number of branches per plant, spread of the plant, number
of leaves per plant, number of days taken for first flowering, number of days
taken for first harvest, duration of harvest, single fruit weight, fruit size,
number of fruits per plant, fruit yield per plant, pericarp thickness, locules per
fruit, number of seeds per fruit, reaction to pests and diseases, colour at
collar of fruits and fruit cracking.
Analysis of variance revealed highly significant differences among the
genotypes for all the characters except for number of locules per fruit. Both
g.c.a. and s.c.a. were significant for all these characters. The additive to

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dominance variance ratio indicated a preponderance for non-additive gene
action in the characters such as spread of the plant, number of days for first
flowering, number of days for first harvest and duration of harvest, and a
preponderance for additive gene action in the remaining characters.
Combining analysis showed that Sakthi and PKM 1 were good general
combiners with respect to fruit yield and other yield attributes whereas LE
79-5 and LE 373 ",!ere good general combiners for the different vegetative
characters such as plant height, branches and leaves per plant. Among the
fifteen hybrid combinations, significant S.C.a. and heterosis were observed in
the hybrids such as Arka Alok x PKM 1, Arka Abha x PKM 1, Sakthi x Arka
Alok, Sakthi x Arka Abha and LE 79-5 x LE 373. Among these hybrids Arka
Alok x PKM 1 showed significance for fruit yield, individual fruit weight, size of
fruit, plant height, leaves per plant spread of the plant and also showed
resistance to mosaic, fruit rot and fruit borer. The hybrid Arka Abha x PKM 1
showed significance for fruits per plant, fruit yield per plant, plant height,
leaves per plant and spread of the plant. The combinations Sakthi x Arka
Alok and Sakthi x Arka Abha showed high s.c.a. and heterosis for fruit weight,
fruits per plant and fruit size and also high heterosis for fruit yield per plant.
LE 79-5 x LE 373 exhibited high s.c.a. for fruit yield per plant and heterosis
for fruit number and fruit yield. Therefore, these hybrids can be utilized for
further crop improvement programme.