I - --ii

10
Table I
Mean yield and range of 70 chickpea lines classified according to their reaction
to ascochyta bight, Tel Hadya, 1979/80 season.
Disease reaction No. of Mean yield Yield range
category lines (kg/ha) (kg/ha) .
Resistant 11 2271 2739 - 1816
Moderately resistant 6 1588 2304 - 1278
Susceptible 45 1003 1247 - 454
Highly susceptible 8 0 ­
sions were found to be resistant. Most of these are now being widely used in the
breeding program.
The Chickpea International Ascochyta Blight Nursery (CIABN) was started
in 1978 to evaluate the sources of resistance identified at Tel Hadya in other
endemic areas throughout the region. The data returned from five countries over
three years indicate that three of the lines were consistently rated as resistant in
all trials. Other lines reacted differentially between the various sites, probably
due to the presence of different pathotypes.
The possibility of new pathotypes overcoming the resistance of a particular
chickpea cultivar is the sword of Damocles hanging over the breeders' (and even
more so the farmers') heads. The probability of such a breakdown of resistance
has not yet been clearly established but breeding strategies at ICARDA are
increasingly being directed towards the development of stable resistance.
On-farm Trials
Many of the sources of resistance identified so far have been in undesirable types
from an agronomic or seed quality standpoint. However, a few were considered to
be promising in all respects. Following a request from His Excellency the Minister
of Agriculture in Syria it was agreed that these should be widely tested
throughout the country. Accordingly, 18 uniform trials were conducted in the
1979/80 cropping season in collaboration with the Department of Agricultural
Research and Extension of the Syrian Ministry of Agriculture. Three resistant
cultivars, and a local susceptible landrace were sown in the winter. A highyielding
line and the local landrace were sown at the normal time in early spring.
The trial was planted both on research stations and on farmers' fields.
Although the local landrace planted in winter performed well in most of the