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