Sources of Resistance to Leaf-Rust of Wheat in Alien Genera and Their Utilization

Three sources of resistance transferred to wheat from alien genera, Aegilops umbellulata (Transfer) Agropyron elongatum (Translocation-4) and Secale cereale (Transec) were tested for resistance to field inoculum of brown rust races. Transec was found to be susceptible at the seedling as well as the mature plant stage while Transfer and Translocation-4 were completely immune at Ludhiana as well as at Keylong (Lahaul and Spiti). The complete immunity of Translocation-4 to a widespectrum of brown rust races and the desirable agronomic characteristics of resistant F₂ segregates in crosses with C. 306, C. 303 and C. 273 indicate that probably Translocation-4 is one of the best sources of brown rust resistance available to wheat breeders. The resistance of T₄ was found to be monogenic dominant in crosses with the varieties C. 303 and C. 306. However, in the cross with C. 273 a 9:7 ratio for resistant and susceptible plants was observed. The departure from 3:1 segregation in this cross has been explained on the basis of reduced transmission of translocated resistance through male gamete.