3.4.43
INCORPORATION OF MULTIPLE DISEASE RESISTANCE TO IMPROVE A BREAD WHEAT VARIETY

RK RANA and SS KARWASRA

Department of Plant Breeding, CCS Haryana Agricultural University, Hisar 125 004, India

Background and objective
Bread wheat is the most important cereal crop in the world, It serves as staple food for most of the world population. Enhancement in grain yield through breeding is important to meet the challenge of the increasing world population. Improvement of the high yielding varieties for disease resistance will certainly contribute to increasing the yield further.

Materials and methods
The basic material for incorporation of disease resistance is the old variety Sonalika which has proved a boon under late sown conditions for enhancing grain yield in northern India over the past three decades. But for some years it has become susceptible to rusts, blight and powdery mildew which reduced its yield potential considerably. To improve this variety it was backcrossed with a suitable resistance source, Lr24, for seven generations, making selections for resistant genotypes in each generation under epiphytotic field conditions. In the end true to type genotypes were selected and bulked together to develop a new improved variety, named Sonak. This variety was evaluated for grain yield, disease resistance and quality attributes over a number of locations and seasons.

Results and conclusions
Sonak variety was tested under December and January sowings against the parent variety Sonalika and another popular check variety, HD 2285, for six years at the main wheat research centre, Hisar and the substations in Haryana state. The average yield performance of Sonak under December sowings was 45.37 q/ha against 41.43 q/ha of parent variety Sonalika and 40.45 q/ha of HD 2285. Under January sowings Sonak gave an average yield of 43.42 q/ha against 36.68 and 39.80 q/ha of Sonalika and HD 2285, respectively. Thus on an average Sonak variety gave 3 to 4 q/ha higher yield than the check varieties.

Regarding disease spectrum, Sonak showed field resistance to leaf rust, yellow rust, leaf blight and powdery mildew over the years against susceptible check varieties. Sonak also showed resistance against shoot fly which damages the crop under late sown conditions. Sonak was also found superior in some quality traits such as protein sedimentation value to the parent variety.

Thus Sonak was found highly sustainable under various agroclimatic conditions and performed better than the parent varieties for yield, multiple disease resistance and quality traits [1, 2]. This improvement resulted through the incorporation of rust resistance gene through backcrossing and interaction with some other genes leading to stable and super performance across the environments [3, 4].

References
1 . Rana RK, Srivastava RB, Karwasra SS, 1994. J. Nuclear Agric. Biol. 23, 182.
2. Singh SS, Mehta H, Sharma DN, Chand N, 1997. Int. Conf. on Integrated Disease Management for sustainable Agriculture. 10-15 Nov. 1997, IARI, New Delhi.
3. Johnson R, 1997. lnt. Conf. on Integrated Disease Management for sustainable Agriculture. 10-15 Nov. 1997, IARI, New Delhi.
4. Singh RP, 1997. lnt. Conf. on Integrated Disease Management for sustainable Agriculture. 10-15 Nov. 1997, IARI, New Delhi.