كليدواژه :
برنج , MAGNAPORTHE GRISEA , مقاومت , بلاست , نژاد فيزيولوژيك
چكيده لاتين :
In this study, the reaction of 116 rice genotypes to blast causal agent (Magnaporthe grisea) field population and its eight races was evaluated. The cultivars were sown at blast nursery in the first days of July (year 2005). The nursery prepared in a shady place, near the Rice Research Institute experimental field, as upland and with high N fertilizer application, in order to maximize the infection rate of cultivars to blast airborne spores. The spore suspension prepared from washing infected leaves of rice (collected from different fields of Guilan province) also sprayed on the nursery. Since the appearance of first blast lesions on rice seedlings, the blast severity measurement started and repeated in order to evaluate the disease progress by time, and 30 days after sowing, the infection type and final severity of blast identified. From 116 cultivars tested, 53 were resistant, with infection type 1-3 (such as Khazar, Sepidrood and Nemat), 24 were semi-susceptible, with infection type 4-5 (such as Fajr, Bejar and Sangjo), and 39 were susceptible, with infection type 6-8 (such as Binam, Hasansaraei and Tarom). Statistic analysis for Area Under the Disease Progress Curve (AUDPC) showed significant differences between cultivars at p=l%. On the basis of Duncan mean comparison of the AUDPC (at p=l%), cultivars divided to 35 groups. Cultivars reaction to eight races of blast from Guilan and Mazandran provinces also studied through greenhouse experiments and major resistance components including infection type, diseased leaf area, sporulated lesions number and mean size of sporulated lesions (mm2) were measured. Statistic analysis of resistance components data also showed significant difference at p=l% between races, genotypes and race- genotype reactions.
