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56<br />
Later Nene et al. (1978) published an annotated bibliography on diseases of<br />
chickpea, including ascochyta blight.<br />
Mycosphaerellarabiei Kovacevski, the perfect state of Ascochyta rabieihas<br />
been reported from Bulgaria by Kovacevski (1936) and from Greece by Zachos<br />
et al. (1963). It has not been reported from any other country, either in nature or<br />
in culture. This is probably the reason that we have relatively less variability in<br />
this pathogen.<br />
Luthra et al. (1941) tested 392 lines and found three lines from USA, namely,<br />
Pois chich Nos. 4732, 199 and 281, which showed a high degree of resistance to<br />
A. rabieiunder varying environmental conditions. For easy reference these lines<br />
were named F 8, F 9 and F 10, respectively. Infection was observed in traces on F<br />
8 with faint, superficial lesions without pycnidia. Line f-0, Deing high yielder and<br />
blight resistant, was distributed to the farmers for cultivation in blight-affected<br />
areas. However, F 8 was susceptible to wilt. Therefore, Ahmad et al. (1949)<br />
released a cultivar C 12-34 (progeny of a cross between F 8 X Pb 7)as resistant to<br />
blight and tolerant to wilt. Cultivar C 12-34 los, "ts resistance to blight in 1950<br />
51. A new cultivar C 235 (cross between F 8 and a high-yielding local chickpea<br />
cultivar) was developed and distributed to farmers (FAO 1963). This cultivar<br />
also lost resistance to blight in the epiphytotic year of 1968, probably due to the<br />
appearance of a new race of the pathogen (Grewal 1969). Keeping in view the<br />
variation in A. rabieiand breakdown of resistance in cultivar C 235, investigations<br />
were undertaken to determine the existence of physiologic races in the<br />
pathogen.<br />
Experiments on Physiological Races<br />
Two hundred and sixty-eight isolations were made from diseased leaves, stems<br />
and pods of chickpea collected from different lines and cultivars from many<br />
localities of the northern states of India during the epiphytotic of 1968. The<br />
isolates were purified and maintained on Potato-dextrose agar (potato 250g; agar<br />
20 g; water 1000 ml) at 25°C, and were named according to the locality from<br />
where they were collected. They were grown on Richards's agar in culture tubes.<br />
On the basis of growth and sporulation, the isolates were grouped into 13 forms.<br />
One representative isolate from each form was taken and its pathogenicity<br />
confirmed on susceptible cultivar Pb 7. The above 13 forms were then grown on<br />
sterilized Richards's agar in Petri dishes (25 ml per plate). They were inoculated<br />
in the center with 5-mm disc of A. rabieiculture (15-day old) and incubated for 3<br />
weeks at 25°C. The data on growth rate, colony color, pycnidial formation and<br />
size of pycnidia are given in Table 1.<br />
Isolates G-31, G-51, G-52, L-24, L-60 and R-21 were relatively fast growing<br />
with fair amount of sporulation (Table 1). Colony color was light pink and the<br />
size of pycnidia relatively smaller than in isolates J 101, G-5, D-30, L-l, L-I 1,