بررسی مقاومت ارقام و لاینهای پیشرفته جو لخت و پوشینه دار نسبت به 4 ایزوله سیاهک سخت ‭(Ustilago hordei) ‬در استان خوزستان

Barley covered smut is the most important spike disease in Khuzestan and cause severe reduction of yield. Primary experiments showed that some lines and cultivars especially hulless barley were susceptible in regard to importance of hulless barley and necessity of its development in province, study on resistant cultivars and advanced hull less and hulled barley lines is very important. In this study and in first year 147 Genotype and in second year 186 Genotype include Commercial, hull less and hulled promising barley and international cultivars in two different dates were sown in nursery and their resistance to this disease was studied. On the basis of obtained result, sowing date could effected on appearance and severity of disease and so we can change sowing date to control and escape from disease. The field results showed that sowing date between 15-30 Azar (6-21 December) with 15 to 20 temperatures is the best time to infection and we have to select this date to screening of cultivars resistance to this disease in Khuzestan province. Among of 186 cultivars and lines, 57 cultivars (7 hulled and 50 hulless) were Immune (0), 24 cultivars, were Resistant with infection about 5% or less than (R), 21 cultivars were Moderately Resistant (MR) (between 5 to 10% infection), 19 cultivars Moderately Susceptible with more than 10 to 15% infection (MS), 10 cultivars were Susceptible (S) (More than 15 to 20% infection) and finally 32 cultivars were Very Susceptible (VS) (More than 20% infection) that 24 cultivars were hull less and 8 cultivar were hulled barley. Caroon and jonoob cultivars were Very Susceptible and Izeh cultivar was almost Immunes and Tropy was Moderately Susceptible also hull less 4 promising barley lines was very Susceptible.