Utilization of genetic stocks in National Genetic Stock Nursery - a "suggested crossing block"
Vinay Mahajan1, NVPR Ganga Rao and Jag Shoran
Division of Crop Improvement, Directorate of Wheat Research, Karnal 132 001, Haryana, India
The success of wheat breeding program primarily depends upon the availability of reliable genetic stocks for key characters. The National Genetic Stock Nursery (NGSN) initiated in 1964-65 was re-constituted into a "Suggested Crossing Block" in 1996-97 at Directorate of Wheat Research, Karnal, wherein confirmed genetic sources from different nurseries are included to assist the plant breeder in making their crossing block more vibrant. Normally the new confirmed genetic stocks are added every year by different programs after years of evaluation. The primary aim of this nursery is to provide confirmed genetic stocks to the wheat breeders of the India as well as to provide the opportunity for evaluation of genetic stocks for agronomic superiority, biotic and abiotic stress tolerance in various wheat growing zones through 35 centers spread throughout the country. The data so generated was compiled and published in the form of Progress Report, Vol II, Genetic Resources every year (Mahajan 1997, 1998, 1999; Mahajan and Ganga Rao 2000, 2001).
Among various other NGSN components, the Latest Agronomic Base (LAB) and Exotic Material (EMAT) are two important components of "Suggested Crossing Block" since 1996-97. The LAB includes the entries from 2nd year of "Advanced Varietal Trial" of bread and durum wheat grown in all the six agro-climatic zones of India. These were among the best performers but lack in some essential agronomic or disease component necessary for a genotype to qualify as variety for release and general cultivation. The supply of these entries to cooperators ranged from 7 (1998-99) to 16 (2000-01)(Table 1) and their exploitation ranged from 12.0 (1998-99) to 19.0 percent (1997-98). The utilization- of genetic stock was computed as:
The selections made on EMAT included genetic materials like synthetic wheat lines and large spike buitre material. These materials were not so good in many characters like threshability, seed filling, quality, susceptible to disease resistance (especially buitre material) etc, but were important sources of biotic and abiotic stress tolerance (synthetic wheat) and very large spike and more grains per spike (buitre material). The genetic material was provided to cooperators primarily for their pre-breeding activities or crossing block. Since 1996-97, 9 (1998- 99) to 14 (1996-97) EMAT were supplied to cooperators in India (Table 1) and their exploitation by cooperators ranged from 15.0 (1998-99) to 29.2 per cent (1997-98).
On understanding the mode of utilization of genetic stocks the two years (1999-2000 and 2000-01) of data revealed that use of genotypes was primarily through hybridization in their breeding programs and in very few cases it was utilized as direct selection in less explored agro-climatic areas. The entries of LAB utilized through hybridization were 11.9 and 12.1 percent during 1999-2000 and 2000-01, respectively (Table 2). However through direct selection the exploitation of LAB genotypes was meager. Similarly the EMAT was primarily used in hybridization with exploitation of 15.7 and 12.9 percent in crop seasons 1999-2000 and 2000-01, respectively.
Hence over the years both the components ie LAB and EMAT, of "Suggested Crossing Block" contributed effectively in enriching the breeding programs of the cooperating centers of India.
Acknowledgments
The authors are grateful to the Project Director, Wheat for guidance and help in execution and transformation of NGSN into a "Suggested Crossing Block". The authors are also grateful to all the cooperators for providing information on the use of genotypes. We are thankful to all the contributors and staff members for their active cooperation in synthesis of an active "Suggested Crossing Block".
References
Mahajan V (1997) National Genetic Stock Nursery. In: Mohan D (ed) Genetic resources identified from national and international nurseries. Crop Improvement Program, Genetic Resource Unit, Directorate of Wheat Research, Karnal: 9-11.
Mahajan V (1998) National Genetic Stock Nursery. In: Mohan D and Shoran Jag (ed) Genetic resources identified from national and international nurseries. Crop Improvement Program, Genetic Resource Unit, Directorate of Wheat Research, Karnal: 9-11.
Mahajan V (1999) National Genetic Stock Nursery. In: Genetic resources identified from national and international nurseries. Crop Improvement Program, Genetic Resource Unit, Directorate of Wheat Research, Karnal: 1-3.
Mahajan V and Ganga Rao NVPR (2000), National Genetic Stock Nursery. In: Mohan D and Shoran Jag (ed) Germplasm evaluation and enhancement. Crop Improvement Program, Genetic Resource Unit, Directorate of Wheat Research, Karnal: 1-3.
Mahajan V and Ganga Rao NVPR (2001) National Genetic Stock Nursery.In: Mohan D and Shoran Jag (ed) Germplasm evaluation and enhancement. Crop Improvement Program, Genetic Resource Unit, Directorate of Wheat Research, Karnal: 1-3.