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All the stem rust pathotypes, except 40A, showed greater degree of virulence to durums, compared to bread wheats. The race 117- pathotypes, particularly 117-6 and 117 A-1, were highly virulent to durum wheats and hence, are essential for evaluating stem rust resistance in durum wheat (Table 2). In fact, only four durum lines, AKDW 3347, B 662, GW 1139 and P 6046 showed resistance to all of the race 117-pathotypes, and to the other stem rust pathotypes as well. The pathotypes 40A, 117-5, 122 and 295 are appropriate for evaluating stem rust resistance in bread wheat, based on their virulence frequencies to the test lines (Table 2).

Further studies are 'm progress to develop definite protocols for systematic evaluation of resistance to stem and leaf rusts in durum and bread wheats.


Acknowledgments

We are grateful to the Head, Directorate of Wheat Research, Regional Station, Flowerdale, Shimla, for supplying the nucleus inoculum of rust pathotypes. Thanks are due to Mr. Jagdish for helping in the glasshouse studies.


References

Honrao BK and Rao VSP (1996) Sources of resistance to race 77 of leaf rust (Puccinia recondita f. sp. tritici) in durum wheat. I. Seedling resistance. Cereal Rusts and Powdery Mildews Bulletin 24: 39-43.

Nayar SK, Prashar M, Kumar J, Bhardwaj SC and Verma LR (1996) Distribution pattern of Puccinia recondita tritici pathotypes in India during 1990-94. Indian J Agri Sci 66 (10): 621-630.

Pandey HN and Rao MV (1984) Differential behaviour of aestivum and durum wheats to races 77 and 106 of leaf rust (Puccinia recondita Rob. Ex Desm.). Wheat Inf Serv 58: 34-35.

Sharma SC, Saini RG and Goel RK (1996) Diversity for new leaf rust resistance genes in some macaroni wheat accessions. Cereal Rusts and Powdery Mildews Bulletin 24: 35-38.

Stakman EC, Stewart DM and Loegering WQ (1962) Identification of physiologic races of Puccinia graminis var. tritici. USDA Agric Res Serv Bull E-617 (rev) :1-53.

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