I - --ii

Table 1
Inheritance of resistance to ascochyta blight in chickpea.
Source Gene Cultivars
Hafiz and Ashraf (1953) Monogenic dominance Fg , Fla
Vir et al. (1974) Monogenic dominarce IP 13
Eser (1976) Monogenic dominance Code no 72-92
Singh and Reddy (1983) (a) Monogenic dominance ILC 72, ILC 183, ILC 200,
ICC 4935
(b) Monogenic recessive ILCI91
in other countries through the Chickpea International Ascochyta Blight Nursery
(CIABN), it will be essential to study the genetics of resistance in greater detail.
Such knowledge is important in planning an effective breeding strategy, especially
in view of the probable existence of physiologic races of ascochyta blight.
Identification of Resistance Genes
Twenty lines identified to be resistant at Tel Hadya for more than 2 years are
being crossed with four testers including three susceptible and one resistant
cultivar (ICL 482). This study is expected to indicate the nature of the inheritance
of resistance to blight and whether the dominant gene already identified in
ILC. 482 is the same as that in other resistant lines having dominant alleles for
resistance.
Pyramiding of Resistance Genes
A 10 x 10 diallel has been designed with the objective of identifying different
resistance genes and incorporating them into a single genotype. This pyramiding
of different resistance genes may provide a better opportunity to a plant breeder
to develop cultivars with a longer life span, i.e. which are not overcome by a new
pathotype. The lines comprise eight resistant and two susceptible genotypes
which originated in different geographic regions. Pyramiding of the resistance
genes will be achieved by crossing the Fls.
Suggestions for Future Study
A certain basic knowledge of the mechanism of disease resistance is vital for
combating ascochyta blight satisfactorily, such as:
1. Biochemical basis of resistance.
2. The extent to which plants can tolerate a certain level of disease without
deleterious effect on yield. Such knowledge will be helpful in shifting emphasis
from the often unstable specific resistance to generalized resistance
conferring an acceptable level of protection with a minimum loss in yield.
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