Evaluating Southern Cone wheat germplasm for spot blotch and tan spot
1998
Kohli, M.M. | Diaz de Ackermann, M.
Since 1981, advanced lines from wheat breeding programs in the Southern Cone region of South America (Argentina, Brazil, Bolivia, Chile, Paraguay, and Uruguay) have been evaluated in LACOS a regional nursery. The nursery is annually seeded in over 25 key locations. Of these, 1-5-report data on spot blotch (Bipolaris sorokiniana) and another 2-4 on tan spot (Drechslera tritici-repentis). Based on 10 years of observations, Santa Cruz (Bolivia) and Londrina (Brazil) represent two critical sites for spot blotch evaluation. Correlation coefficients among infection indices from various locations during a severe disease year (1994) show not only low, statistically significant relationships between Bolivia and Brazil (r = 0.142* - 0.214* ), but also indicate that pathogen populations may differ within a country such as Brazil. Tan spot infection, on the other hand, has been increasingly evaluated at Pergamino (Argentina), Bella Vista (Paraguay), and Young (Uruguay). While the relationship among these locations is low but statistically significant (r = 0.219** - 0.267* ), there is a possibility of a differential pathogen population between Paraguay and Uruguay. Of the commercial varieties tested in 1994/95, most are moderately to highly susceptible; however, some varieties such as Don Ernesto INTA, ProlNTA Federal, and ProlNTA Guazu from Argentina; Domo INIA, Saeta INIA, and Chagual INIA (durum) from Chile; IAN 7 and Itapua 35 from Paraguay; and ProlNTA Superior and E. Pelon 90 from Uruguay demonstrated moderate spot blotch resistance levels. During the same year, IAC 5 - Maringa from Brazil; Domo INIA, Nobo INIA, and Saeta INIA from Chile; E. Cardenal, E. Pelon, and ProlNTA Querandi from Uruguay; and IAN 7, IAN 9, Itapua 35, and Itapua 40 from Paraguay showed moderate tan spot resistance.
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