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International Maize and Wheat Improvement Center - CIMMYT

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Evaluation of elite triticale (X Triticosecale) genotypes for resistance to Karnal bunt (Tilletia indica Mitra) under artificial field inoculation in the Yaqui Valley, Sonora, Mexico, during the 2003-04 crop cycle. [p.83-85]

Guillermo Fuentes-Dávila and Karim Ammar.

Introduction. Karnal bunt occurs naturally on bread wheat (Mitra 1931), durum wheat, and triticale (X Triticosecale; Agarwal et al. 1977). Affected kernels are usually partially infected and completely infected ones are rare (Mitra 1935; Bedi et al. 1949; Chona et al. 1961). Since the early 1980s, it has been reported about the resistance and immunity shown by triticale cultivars and experimental advanced lines under artificial inoculations (Meeta et al. 1980; Fuentes-Davila et al. 1992); therefore, advanced lines were selected primarily for their resistance to a new race of yellow rust that appeared in Central Mexico and to which most CIMMYT triticales are susceptible (Hede et al. 2002). Sources of resistance to this race also include progenies from crosses with either bread or durum wheat. Continued evaluation for new developed advanced lines and cultivars is important as a measure to avoid possible economic problems to farmers, that could result from the release of a susceptible cultivar.

Materials and Methods. Twenty elite triticale advanced genotypes were evaluated for Karnal bunt resistance during the crop cycle 2003-04. Planting dates were 20 November and 5 December, 2003, using approximately 10 g of seed for a bed with two rows 1-m long. A mist-irrigation system was used 3-5 times/day for 15 min each time to provide a humid environment in the experimental area. Inoculation was by injection during the boot stage applying 1 ml of an allantoid sporidial suspension (10,000/ml) to ten heads/genotype. Harvest was manual, and evaluating and counting of healthy and infected kernels was by visual inspection. Tested genotypes included the long-term yield check Pollmer TCL 2003, recently released as feed-grain cultivar in the state of Sonora, and two new candidates for commercial release in the same state. These three genotypes are susceptible to yellow rust in central Mexico. The remaining 17 genotypes are new advanced lines selected for their resistance to yellow rust in the Central Mexican Highlands and, internationally, represent the genotypic variability available in the current feed and forage triticale germ plasm of the CIMMYT program.

Results and Discussion. The range of infection for the first planting date was 0-9.47, with a mean of 1.13. Ten lines did not have any infected kernels (Figure 1). The range of infection for the second planting date was 0-0.92, with a mean of 0.11. Sixteen lines did not have any infected kernels. The difference between the mean percent infection of the first and second planting dates and the mean of the three highest levels of infection of the susceptible check WL711 (65.98 %) was 64.9 and 65.87 %, respectively (Figure 2). Only the line Dahbi_6/3/Ardi_1/Topo 1419//Erizo_9/4/Copi_1-1, CTSS99B00002S-0M-1Y-1M-1Y-0M, fell within the 5.1-10 % infection category with 9.47 % on the first date. Lines with less than 5 % infection are considered resistant (Fuentes-Dávila and Rajaram 1994). Nine lines did not have any infected kernels in either evaluation (Table 1). These results indicate that the high level of resistance to Karnal bunt in triticale has been maintained in the new elite germ plasm coming out of the CIMMYT program. Collaborative efforts between INIFAP and CIMMYT to ensure adequate levels of Karnal bunt resistance in new promising material is being continued in order to provide a sound, safe, and commercially viable feed grain option for the growers in the state of Sonora.

References.

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• Bedi SKS, Sikka MR, and Mundkur BB. 1949. Transmission of wheat bunt due to Neovossia indica (Mitra) Mundkur. Ind Phytopathol 2:20-26.
• Chona BL, Munjal RL, and Adlakha KL. 1961. A method for screening wheat plants for resistance to Neovossia indica. Ind Phytopathol 14:99-101.
• Fuentes-Davila G and Rajaram S. 1994. Sources of resistance to Tilletia indica in wheat. Crop Prot 13(1):20-24.
• Fuentes-Davila G, Rajaram S, Pfeiffer WH, and Abdalla O. 1992. Results of artificial inoculation of the 4th Karnal Bunt Screening Nursery (KBSN). Ann Wheat Newslett 38:157-162.
• Hede AR, Skovmand B, Singh R, Payne T, Huerta J, Ammar K, and Rajaram S. 2002. The importance of germplasm diversity for triticale breeding. In: Proc 5th Internat Triticale Symp, Radzików, Poland, 30 June-5 July, 2002. Pp. 67-76.
• Meeta M, Dhiman JS, Bedi PS, and Kang MS. 1980. Incidence and pattern of Karnal bunt symptoms on some triticale varieties under adaptive research trial in the Punjab. Ind J Mycol Plant Pathol 10:LXXXIV.
• Mitra M. 1931. A new bunt of wheat in India. Ann Appl Biol 18:178-179.
• Mitra M. 1935. Stinking smut (bunt) of wheat with a special reference to Tilletia indica Mitra. Ind J Agric Sci 5:1-24.