Evaluation of resistance of the genotypes of Preliminary, Advanced and Elite Regional Wheat Yield Trials (PRWYT – N, ARWYT-N, ERWYT-N) of the North warm and humid zone to powdery mildew (2012-2013)

Powdery mildew caused by Blumeria graminis f.sp. Tritici is one of the most important diseases of wheat in temperate to subtropical areas with high rainfall and humidity. The different wheat genotypes are different in tolerance, disease severity and yield loss. Since the use of resistant or tolerant varieties is the most effective way to control it, therefore this project 194 wheat genotypes resistant consists of 134 lines of preliminary warm and humid of north zone, 40 advanced wheat lines, 20 of cropping season 1391-92 with 20 elite wheat lines cropping season 1391-92 were studied in field conditions in Iraqi Mahalle (Gorgan) research stations and Gharakhail (Ghaemshahr). Genotypes were planted in two rows one meter apart on a stack of 30 cm and 60 cm distance ridges without replications. Nursery inoculation was conducted in the stem elongation stage by inserting plastic pots containing infected cultivar Bolani between genotypes in the nursery experiment. The genotypes react were performed in two stages in booting and flowering stage in Iraqi Mahalle (Gorgan) and one stage in milk stage in Gharakhail (Ghaemshahr) with using two numbers (00-99) altered Eyal and colleagues (Eyal et al., 1987). At the end of the genotypes were grouped with respect to the amount and intensity of infection on susceptible varieties with few modifications and based on 00 means immune; 00-11 resisting means, 12-31 meaning moderately resistance, 32-51 means moderately susceptible, 52-71, and 72-99 means to be very susceptible response (Wang et al., 1993). Results of performance in Mazandaran and Golestan genotypes showed that the reaction against the pathotype of the two regions is almost identical. As showed that resistance or susceptibility lines number in both the place was high. So in the Gharakhail station 70% and in Iraqi Mahalle (Gorgan) 78% of the lines showed moderately resistant reaction.While 25.5% and 18%, respectively, semi-sensitive disease attributed to the local Gharakhail and Iraqi Mahalle station, and 2-4% of this lines showed susceptible to both regions. Advanced lines had the same reaction conditions, so that 60% of lines were moderately resistant reaction and 40% susceptible in Gharakhail station. Same lines in terms of local Iraqi Mahalle station were 45%, 35% moderately resistant, and 20% fully susceptible. Also elite lines 1391-92 in Gharakhail station showed 60% moderately susceptible, 10% moderately resistant and 30% moderately susceptible and in the Iraqi Mahalle station , 25% moderately resistant, 50% moderately susceptible and 5% susceptible to wheat powdery mildew. The elite genotypes 1390-91 cropping season that were examined for two year in two station research, so this lines were in Gharakhail station 30% and 70% moderately resistant or moderately susceptible respectively and 50% moderately resistant and moderately susceptible reaction in Iraqi mahalle station to disease against.