International Journal of Life Science and Agriculture Research

A field and laboratory study was conducted from November 2021 to April 2022 at Debchuli-2, Nawalpur (East), Nepal, to evaluate 50 wheat genotypes for resistance to spot blotch (caused by Bipolaris sorokiniana) and associated traits. The experiment followed an alpha-lattice design with three replications. Disease severity was assessed using single and double-digit scales at four intervals post-heading, and area under disease progress curve (AUDPC) was computed to categorize genotypes into resistant, moderately resistant, susceptible, and highly susceptible groups. Laboratory seed health testing was performed using the blotter method to assess seed infection by B. sorokiniana. AUDPC values varied significantly among genotypes, ranging from 178.4 (resistant) to 487.5 (highly susceptible). Genotype YMI#6 had the lowest AUDPC, while RR 21 exhibited the highest, indicating loss of previously reported resistance. Root rot index (RRI) ranged from 17% to 44% and positively correlated with AUDPC. Significant variation was observed in yield and yield-attributing traits, including thousand kernel weight (TKW), grain yield, and spike characteristics. Grain yield showed a significant negative correlation with AUDPC (r = -0.280*), while TKW was positively correlated with grain yield. Phenological observations revealed that susceptible genotypes had earlier booting, heading, and maturity. A negative correlation was found between AUDPC and days to maturity (r = -0.57*), indicating accelerated development in diseased plants. Plant height also differed significantly among resistance categories. The study highlights genetic variability among genotypes in response to spot blotch and identifies promising resistant lines for wheat improvement programs in subtropical regions.

AUDPC, Bipolaris sorokiniana, Genotypes, Resistance, Screening, Susceptible

1. Bhandari, D. 2000. Response of wheat genotypes to seed infection, root rot, spot blotch caused by B. sorokiniana and its pathogenic variability. M.S. Thesis, Tribhuvan University, Department of Plant Pathology, IAAS, Rampur, Chitwan, Nepal. Pp40.
2. Dubin, H. J. and M. Van Ginkel. 1991. The status of wheat diseases and disease research in warmer areas. Wheat for the nontraditional warm areas: a proceedings of the International Conference July 29-August 3 1990 Foz do IguaÇu, Brazil., 125-45.
3. Dubin, H. J., B. Arun, S. N. Begum, M. Bhatta, R. Dhari, L. B. Goel, A. K. Joshi, B.M. Khanna, P. K. Malaker, D. R.Pokhrel, M. M. Rahman, N. K. Saha, M. A. Shaheed., R. C. Sharma, A. K. Singh, R. M. Singh, M. Vergas, P. C. Verma, 1998. In: E. Duveiller, H. J. Dubin, J. Reeves, A,Mc- Nab,. (eds.). Helminthosporium Blights of Wheat: Spot blotch and tan spot. Result of south Asian regional Helminthosporium leaf blight and yield experiment 1993-1994, CIMMYT, El Batán, DF, Mexico. pp. 182-187.
4. Duveiller, E. M., and Sharma, R. C. 2009. Genetic improvement and crop management strategies to minimize yield losses in warm non‐traditional wheat growing areas due to spot blotch pathogen Cochliobolus sativus. Journal of Phytopathology, 157(9), 521-534.
5. Duveiller, E., & L. Gilchrist. 1994. Production constraints due to Bipolaris sorokiniana in wheat: Current situation and future prospects. In: D. A. Saunders, G. P. Hettel (eds.), Wheat in heat stressed environments: Irrigated, dry areas, and rice- wheat Farming Systems, pp. 343-352.CIMMYT, El Batán; DF, Mexico.
6. Gilchrist, L. I., W. H. Pfeiffer, and C. Velasquez. 1992. Resistant to Helminthosporium sativumin bread wheat: Relationship among infected plants and association with agronomic traits. In: D. G. Tanner, and W. Mwangi (eds.), Seventh regional wheat workshop for Eastern Central and Southern Africa. Nakura, Kenya: CIMMYT. Pp. 176-182.
7. Kaur, S., Dhaliwal, L., & Kaur, P. (2008). Impact of climate change on wheat disease scenario in Punjab. Journal of Research, 45(3-4), 161-170.
8. Mahto, B. N. 2001.Effect of Helminthosporium leaf blight on yield components and determination of resistance in selected wheat varieties. Annuals of Agricultural Research 22:177-181.
9. MoALD. 2024. Statistical information on Nepalese agriculture, Government of Nepal, Ministry of Agriculture and Cooperatives (MOAC).Agribusiness Promotion and Statistics Division, Singh Durbar, Kathmandu, Nepal. 121p.
10. Navathe, S., Yashavanthakumar, K. J., Pandey, A. K., Patil, R. M., Baviskar, V. S., & Chand, R. (2022). Leaf blight disease of wheat and barley: Past, present and future. In New Horizons in Wheat and Barley Research: Crop Protection and Resource Management (pp. 77-105). Singapore: Springer Nature Singapore.
11. Paulitz, T. C. (2006). Low input no-till cereal production in the Pacific Northwest of the US: the challenges of root diseases. European Journal of Plant Pathology, 115, 271-281.
12. Raemakers, A. H. 1987. Helminthosporiumsativum: Disease complex on wheat and sources of resistance in Zambia. In: A. R. klatt (ed.), heat production constraints in tropical environments. A proceeding of the international Conference, 1987. CIMMYT, Mexico, D. F. pp. 175-185.
13. Rosyara U. R., K. Khadaka.,S. Subedi., R. C. Sharma., and E. Duveiller.2009. Field Resistance to spot blotch is not associated with undesirable physio-morphological traits in three spring wheat populations. Journal of plant pathology 91:113-122.
14. Sharma, R. C., H. J. Dubin, R. N. Devkota, and M. R. Bhatta. 1997. Heritability estimates of field resistance to spot blotch in four spring- wheat cresses. Plant Breeding. 116: 64-68.
15. Shrestha, K. K., R. C. Timila, B. N. Mahto, and H. P. Bimb. 1998. Disease incidence and yield loss due to foliar blight of wheat in Nepal. In: E. Duveiller, H. J. Dubin, J. Reeves and A. McNab (Eds.), Helminthosporium blight of wheat: spot blotch and ten spot. CYYMYT, Mexico, D.F.pp.59-62.
16. Singh, J., Chhabra, B., Raza, A., Yang, S. H., & Sandhu, K. S. (2023). Important wheat diseases in the US and their management in the 21st century. Frontiers in plant science, 13, 1010191.
17. Tinline, R. D.1977.Multiple infection of subcrown internode of wheat by common root rot fungi. Canadian journal of Botny 55: 30-40.
18. Toledo, B. J. and E. A. Guzman. 1998. Importance of spot blotch caused by Bipolaris sosokiniana in Bolivia. In: Duveiller, E,. H. J. Dubin, J. Reeves, and A. McNab (eds.), Helminthosporium blights of wheat: Spot blotch and tan spot, CIMMYT, Mexico, D.F. pp.146-149.
19. Xiong, Y., McCarthy, C., Humpal, J., & Percy, C. (2023). A review on common root rot of wheat and barley in Australia. Plant Pathology, 72(8), 1347-1364.