Breakdown and inheritance of resistance to leaf rust in bread wheat cultivars DL 788-2, GW 322, HUW 533 and HW 2045.

Wheat leaf rust caused by Puccinia triticina Eriks. (P. recondita Rob. ex Desm. f. sp. tritici Eriks. & Henn.) is widespread throughout the wheat (Triticum aestivum L.) growing areas of the country. India has become the second wheat producer country next to China in the world. Resistance breeding forms a vital component of strategies for management of diseases. Knowledge of the resistance make-up of the existing varieties and sources of resistance is essential for an effective breeding programme. Till now nearly 51 Lr genes have been described (4). Wheat cultivar DL 788-2 released in 1996 and cultivars, GW 322, HUW 533 and HW 2045 released in 2001 showed resistance to all the three rusts at the time of their release. But, recently some of them exhibited breakdown of resistance. An attempt has been made here to study the nature and number of resistance genes operating in above cultivars to leaf rust.