F DÜSÜNCELI¹, S ALBUSTAN¹, L ÇETIN¹ and SPS BENIWAL²

Background and objectives
Of the three rust diseases (Puccinia spp.) that are among the major constraints to bread wheat cultivation in West Asia and North Africa, stripe rust (P. striiformis West. f.sp. tritici) is the most prevalent especially in humid and cooler areas. Stripe (yellow) rust (YR) epidemics in the last decade caused significant economic losses. Over 0.5 million tonnes of wheat loss was estimated due to the 1995 YR epidemic in the Çukurova region of Turkey [1]. Similar losses have been recorded in other countries in the region [2].

The most economical means of protection against rusts is the development and utilization of resistant cultivars. To facilitate this in the region, the International Center for Agricultural Research in the Dry Areas (ICARDA) based in Aleppo, Syria, in collaboration with CIMMYT, has been developing wheat germplasms with resistance to diseases of regional importance. This study was undertaken (i) to assess suitability of ICARDA/CIMMYT bread wheat germplasms for utilization in Central Anatolia as YR adult plant resistance sources, and (ii) to compare their YR resistance performance in Ankara with previous findings in middle-eastern countries.

Materials and methods
Trials were conducted at the Ikizce research farm of the Central Research Institute for Field Crops (CRIFC), 45 km south-west of Ankara, at 1150 m altitute. The six international nurseries, provided by ICARDA/CIMMYT, consisted of five germplasm pools (GP) for resistance to YR (WYRGP-96), YR and bunt (WYRBGP-96), stem rust (WSRGP-96), leaf rust (WLRGP-96), Septoria tritici (WSTGP-96), and Bread Wheat Key Location Nursery (WKL-96) which contained lines from advanced yield trials that had been primarily screened for disease resistance in Syria. Numbers of entries were 8, 34, 18, 11, 11 and 200, respectively. Of the WKL entries, 20 were susceptible and resistant checks.

The entries were hand-sown in 2-m rows, with a susceptible check Michigan Amber (MA) repeated after every 10 entries, on October 20, 1996. Spreader borders consisting of MA, Little Club and Turkish variety Sürak 1593/51 were sown around the field. The inoculum was collected from around Ankara in the previous year, stored in liquid nitrogen and multiplied in a greenhouse in spring. The inoculum carrying virulences for YR 2, 6, 7, 9 and A+ was applied in talc powder and in mineral oil in March-April. The nurseries were sprinkle irrigated. Scoring was made using the Modified Cobb scale.

Results
Good artificial epidemic development was achieved allowing efficient evaluation of the nurseries. MA, the susceptible check, scored between 70S-80S. Of the other checks, Mexipak scored between 760S and 70S while Cham 6 and Bocro showed complete resistance. Most of the WKL entries showed high level of resistance, probably owing to efficient preliminary screening, in Syria. The number of lines with average coefficient of infection (ACI) of less than 1, 10 and 20 was 137 (76.1%), 139 (77.2%) and 145 (80.5%), respectively. None of the lines exceeded ACI of 50.

Of the GP nurseries, all nine YRGP entries showed high level of YR resistance, the highest score being 20 MSS and the remaining having ACI values of under 4. This was similar to the observations of ICARDA taken from Syria, Lebanon, Yemen and Egypt in previous years. In nurseries of YRGP, SRGP, LRGP, YRBGP and STGP, 9, 15, 9, 29 and 9 entries gave ACI values of under 20, respectively. Among the 82 GP entries the most remarkable cross was Bow #1/Fenkang 15 which gave ACI of less than 10 in 17 entries, and ACI of 18 in one entry. The differences between the ACI values of the GP entries in Ankara and Tel Hadya-Syria varied between 0-59. They were significantly higher (over 18) in Ankara only for nine (10.9%) entries. In 89.1 and 72.9% of the entries the ACI difference was under 10 or 5, respectively. The study indicated that YR resistance of the tested germplasm is mostly similar at both locations and thus could be exploited for use in the Central Anatolia of Turkey.

References
1. Düsünceli F, Çetin L, Albustan S, Beniwal SPS, 1996. Cereal Rusts & Powdery Mildews Bulletin, Vol. 24, Supplement, pp. 309.
2.Torabi M, Nazari K, 1997. Wheat: Prospects for global improvement (eds. H.J. Braun et.al. ), pp.109-112.