In recent years, emphasis in wheat improvement work has shifted to breeding for disease resistance, particularly to rusts. Certain foreign wheat varieties belonging to the vulgare group showed resistance to brown and yellow rusts and could be used for breeding purposes. For black rust, however, the situation was quite different and in the beginning, resistance had to be sought for in the dicoccum wheat, Khapli. Meanwhile, a valuable source of resistance for black rust was discovered in certain vulgare wheats from Kenya, thus obviating the need for interspecific hybridization. The two Kenya wheats, E. 144 and E. 220, were widely used as resistant parents in crosses with improved Indian wheats. The cross Kenya E. 220 X N.P. 165 yielded the strains, N.P. 797, N.P. 798 and N.P. 799 which combine in them resistance to black and brown rusts and to loose-smut. These new strains are early in maturity and gave good performance in the trials that were conducted at different locations throughout the country.
In Bihar, these varieties gave decidedly better performance than the others but among themselves they had interchanged the positions. In general, N.P. 798 and N.P. 799 gave better performance. In Bombay N.P. 798 showed promise in the Saurashtra region. In Delhi the performance of N.P. 797 was consistently outstanding. In Hyderabad, N.P. 798 has a good chance owing to its rust resistance. In Madhya Pradesh N.P. 718 and N.P. 710 gave better performance than these newer wheats. In Rajasthan the performance of N.P. 718 was better than that of the other varieties. The next best was N.P. 797, closely followed by N.P. 798. In West Bengal the performance of these new wheats was satisfactory. N.P. 799, closely followed by N.P. 798, did best in Malda which is an important wheat growing region of West Bengal.
The number of days taken for ear emergence was recorded in the various States. The results clearly showed that in all the States ear emergence of the new wheats, N.P. 797, N.P. 798 and N.P. 799 was earlier than that of the other varieties.
The rust resistance of these wheats was tested against individual races in the seedling stage as well as to a mixture of races in the adult stage. At Delhi and Pusa the adult reaction in the field was tested under artificial conditions of infection and at a number of other locations the reaction under natural conditions of infection was recorded. These observations showed that the new wheats possessed a good degree of resistance for black and brown rusts and were highly resistant to the loose smut disease. Based on their yield performance, early maturity and disease resistance, the new N.P. wheats seem to be highly suitable for the States of Bihar and West Bengal as these States are frequently subjected to severe attacks of rust.
