I - --ii

Hybridization
Three methods of selection, namely, pedigree, bulk and backcross are available
after hybridization in a self-pollinated crop like chickpea. Some of the genes for
resistance to blight have been found in a background that can also contribute to
improved adaptation and yield. This provides an opportunity of choosing either
the pedigree or bulk mcthod of handling segregating generations. The pedigre
method has been widely used in breeding for disease resistance and the majority
of disease-resistant cultivars have been produced by this method (Allard 1960).
The bulk population method of breeding is largely adopted by plant breeders to
advance the segregating populations with ease and to allow natural selection to
play a role. Both the pedigree method of selection for development of cultivars
with a high yield, resistance to blight and wide adaptation, and the bulk population
method 6f selection for development of large-seeded types with high yield,
blight resistance-and less photoperiod-sensitivity have been adopted. The procedures
and progress made are described.
Pedigree Method
Crosses are made between adapted and high-yielding cultivars and blight-resistant
lines and the resulting hybrid populations are handled as shown schematically
in Fig. 1.The Fl generation is grown in the off-season at Terbol (in the Beqa'a
valley of Lebanon). The F2 generation is sown in the blight disease nursery at Tel
Hadya (near Aleppo, in northern Syria) and resistant plants with desirable traits
for simply inherited characters, such as maturity, height and seed characteristics
are selected. F3 progeny rows are grown in the off-season at Terbol and single
plants are selected from superior progenies. Again selection is made for normal
maturity, which under the decreasing day length at the end of the season, may
also be associated with reduced photoperiod-sensitivity. F4 progeny rows are
grown back in the disease nursery at Tel Hadya and single plants are visually
selected from superior yielding and resistant progenies. F5 progeny rows are
again grown at Terbol where selection for maturity is practised and filally F6
progeny rows are grown in the disease nursery in an augmented design with three
checks for the identification of superior yielding, disease-resistant and uniform
progenies which are then bulked for replicated yield testing. Selection f~r maturity
assumes importance because many of the sources of resistant genes are
present in lines originating from the USSR and are usually late in matIrity.
The material in hand and their disease resistance is shown in Tab. 2. It may be
seen from this table that 375 lines resistant to ascochyta blight are available in
the program which is now being further expanded.
Since the aim is to develop resistant cultivars suitable for winter, early spring
and normal spring sowing, the material from the F5 generation onwards will be
grown in all planting seasons to allow selection of material adapted to the various
ecosystems.
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