Raj Molya Rodhak 1, a first commercial unique wheat variety resistant to cereal cyst nematode in India

B. N. Mathur, S. N. Sharma, V. K. Bhatnagar, G. L. Sharma, R. S. Sain, S. M. Bhatnagar, Hoshiyar Singh, A. Mishra, C. P. Nagpal and R. L. Midha

All India Coordinated Wheat and Barley Improvement Project, Rajasthan Agriculture University, Agricultural Research Station, Durgapura, Jaipur 302 018, Rajasthan, India

Of the several constrains towards realizing potential yield in wheat, losses incurred due to molya disease is enormous. This disease is used to cause about 40-50 percent yield loses, which may attain up to 60-65 percent (Mathur 1969; Mathur et al. 1980). Looking towards the state wheat production (5.99 m tones), the cereal cyst nematode (CCN) infested area (0.15 m ha) instead of producing 0.43 m tones, only yielding 0.22 m tones (2001-02) and grain loss in terms of money amounts about Rupees 126 million. It is observed that high yielding and well adopted modern varieties when grown extensively under CCN infested areas, the high incidence of this disease results in epidemic proportions and causes grain as well as straw yield losses. Earlier certain efforts using cultural practices and chemicals were also exercised to overcome the threat of CCN in naturally infested soils of Rajasthan, as the basis of genetically defined CCN resistance sources during this period was not known. It was felt that deployment of CCN resistance resources for this disease resistance could assist in achieving yield stability without resorting potentially harmful chemicals, at the same time preventing environmental degradation and benefiting the resource-poor farmers who can ill afford the use of costly chemicals to sustain the yield in infested soils (Mathur et al. 1998). Hence, breeding for CCN resistance based on genetic principles was initiated in 1991, soon after the identification of AUS 15854, a Turkish wheat line received from Australia, demonstrated for the first time that resistance to CCN in wheat was controlled by a single dominant gene under warmer condition of Rajasthan, India. The progress achieved to check the severe losses of yield due to the cereal cyst nematode (Heterodera avenae)by developing a unique CCN resistant wheat variety CCNRV 1 (Raj Molya Rodhak 1), dealt with in this paper.

The breeding program was initiated in 1991 for development of CCN resistant wheat variety for sustained and maximization of wheat production in molya infested areas of the country. Seven popular high yielding bread wheat (Triticum aestivum L.) varieties namely J-24, Raj 2184, Raj 3077, HD 2329, Raj 2535, HD 2009 and Kalyansona were selected for hybridization program. The AUS 15854 genotype was used as a male parent. Pedigree method was followed in handling the segregating generations under artificially CCN infested field in each generation. In the first instance, selection was based on visual assessment of single plant in the sick field, backed up by rapid CCN resistant and grain quality tests. Yield traits and CCN resistance were fixed in the fifth generation and a new variety is typically multiplied up from a single plant in sixth generation. From each cross combination one of the best plant progeny was selected and bulked on the basis of CCN resistance and other desirable traits for further evaluation in yield trials at various locations. The selected seven plant progenies were designated as CCNRV 1 (J-24 x AUS 15854), CCNRV 2 (Raj 2184 x AUS 15854), CCNRV 3 (Raj 3077 x AUS 15854), CCNRV 4 (HD 2329 x AUS 15854), CCNRV 5 (Raj 2535 x AUS 15854), CCNRV 6 (HD 2009 x AUS 15854) and CCNRV 7 (Kalyansona x AUS 15854) for convenience in testing in the trials.