Meeting the Challenge of Yellow Rust in Cereal Crops - ICARDA

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Breeding for qualitative resistance is a widely adopted method. This paper
introduces seven promising lines of drought-tolerant, stem and yellow rustsresistant
and high yielding bread wheat. Two sets of wheat material, including
44 F 3 segregating populations and 100 drought-tolerant high yielding lines
received from ICARDA were evaluated in Early Generation tests and an
Advanced Yield Trial, respectively, at Seed and Plant Improvement Institute
(SPII), Karaj, Iran, during the 2003/04 cropping season in two sets of
experiments.
In the first set, the 44 F 3 segregating populations were planted under mist
conditions and the selected bulk method was used to handle the F 3 generation.
Selected plants from the segregating populations were planted under terminal
drought stress (TDS) conditions to assess their drought tolerance through to
the F 6 generation. Selected pure lines were then tested for grain yield in
Regional Preliminary Yield Trials at Karaj (temperate zone) and Ardabil
stations (cold zone) as the F 7 generation in 2007/08. The selected lines were
then sent to Kenya for evaluation of their reaction to the aggressive new stem
rust race (Ug99). Data received from Kenya showed resistance to Ug99 in four
selected lines with pedigrees 474S10-1/Bolero/3/Tirchmir 1/LCO//Sabalan;
130L1.11//F35.70/MO73/4/YMH/TOB//MCD/3/Lira/5/Tirchmir 1/LCO//Sabalan;
Skauz/4/TJB916.46/CB306//2*MHB/3/BUC/5/Tirchmir 1/LCO//Sabalan;
and Sabalan/KINACI97. The selected lines showed an acceptable level of
resistance to yellow rust race 166E134A+. Determination of yield stability was
carried out using a non-parametric ranking statistic method, and results
showed that these four lines with good resistance to Ug99 and 166E134A+,
Yr27+ races also had yield superior to the check cultivars.
In the second set of experiments, 100 advanced lines were planted in an
alpha lattice design Advanced Yield Trial under TDS conditions and relevant
agronomic and morphological traits, grain yield and reactions to rusts were
recorded. Selected lines were evaluated for rust resistance in several hot-spots
over three cropping seasons and evaluated for grain yield stability and
adaptability on four agricultural research stations for two years. Considering
both the recorded stem rust data from Kenya, and yellow rust data from hotspot
sites in Iran, and based on grain yield, five superior drought-tolerant lines
were selected from this trial. The lines Bkt/Zhong; OK82282//BOW/NKT/3/
SARDARI-HD 75; SARDARI-HD 93/6/SN64//SKE/ 2*ANE/3/SX/4/ were
resistant to the 166E134A+, Yr27 yellow rust race, but were susceptible to
Ug99. Although the line with pedigree of AGRI/BJY//VEE/3/PRINIA was
moderately-resistant to Ug99, it showed high susceptibility (90S) to a new
yellow rust race. The new line (SARDARI-HD83//LINFEN875072/KAUZ)
was resistant to both stem rust (Ug99) and yellow rust (166E134A+, Yr27+)
with high yield under both irrigated and TDS conditions.