| Rice blast caused by Magnaporthe grisea is as one of the most destructive disease in rice in the whole world. Blast resistant breeding and growing resistant cultivars are the most efficient measure to control the disease. Therefore, the dissertation has firstly put into combining both blast nursery and resistant breeding, and carried out studies on population genetic structure of the blast pathogen similarity, identification of rice cultivars and lines resistant to blast and using diversity of rice varieties for sustainable control of rice blast.Liuyang Daweishan Rice Blast Nursery, it locates at Daweishan National Forest Park, Rongwan village, Daweishan town, Liuyang city, viz. 114° 5' E, 28° 30' N, about 400m with elevation, and belongs to the season wetness climate with central Asia tropics that has annual average temperature with 17.3℃,average 5.2℃ and 28.9℃ in January and July separately, rainfall with 1 552mm, yearly average sunlight with 1 656h and no frost duration with 262d. Based on observation during rice growing, time of keeping free water on rice leaves was more than 15h. So the blast nursery through 7 350 rice entries test has been proved that it is a sustainable nursery and breeding base with strongly differential ability and a good natural isolation condition.7 350 entries, including varieties and lines, in the nursery were tested in 2002 and 2003. The results indicated that there were 491 from high resistance (HR) to moderate resistance (MR) and 2 892 from high susceptibleness (HS) to moderate susceptibleness (MS) for leaf blast, which had HR-MR frequency of 14.52% and HS-MS one of 85.48% in total 3 383 entries in 2002, while 769 entries with HR-MR and 2 084 entries with HS-MS for panicle blast, which had HR-MR frequency of 26.94% and HS-MS one of 73.05% in total 2 853 entries under eliminating 530 8-9 score entries in 2002; the same had 709 entries with HR-MR and 3 258 entries with HS-MS for leaf blast, which had HR-MR frequency of 17.86% and HS-MS one of 81.41% in total 3 967 entries in 2003, and 1 094 entries with HR-MR and 1 458 entries with HS-MS for panicle blast, which had HR-MR frequency of 42.82% and HS-MS one of 57.15% in total 2 552 entries under eliminating 1 415 8-9 score entries in 2003.Entries of 8~9 score for leaf blast and 7~9 score for panicle blast during breeding screening in the nursery are eliminated based on selective pressure in the disease nursery more than other areas outside the nursery. Results of F1, F2, F3 and F4 of 1 061 combinations suggests that F2, F4, F6 or F2, F3. F5 as conventional breeding and Fl as hybrid rice breeding should be carried out in the blast nursery. If we can do so, efficacy of blast resistant breeding will be greatly enhanced.Resistant lines planted around the disease area in outside nursery, which were tested fromthe rice blast nursery, could effectively control rice blast and their control efficacy had 90%. Using lines mixture for rice blast had also have good control efficacy, in which the combinations of high resistant lines with high susceptible variety were better than of resistant lines with high susceptible variety in control blast. Besides, suitable application of the fungicide had still highly good effectiveness for rice blast in the field test, but different fungicides showed some variation in efficacy of control blast. |
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