控制大豆花叶病毒危害的种子带毒率临界水平

控制SMV危害的种子带毒率临界水平,因年度间介体蚜量发生程度不同而变化。大豆田有翅蚜大量迁飞活动的年份也是蚜虫大发生的年份。播种感病品种,蚜虫轻发生年控制SMV危害的种子带毒率临界水平为0.5％;中等偏轻年份为0.2％;中等发生年份为0.1％;而中等偏重发生年份为0.04％;大发生年则为0.01％。因此,可根据不同年份介体蚜虫发生的程度决定所播种子的带毒率水平,控制SMV危害。文中还讨论了获得低带毒率种子的方法,并提出应该将种传率的高低,作为鉴定大豆品种抗感SMV的一个指标。

CRITICAL LEVEL OF SEED-TRANSMISSION RATE OF SMV CONTROLLING YIELD LOSS OF SOYBEANS

The critical level of seed-transmission rate of SMV which controls the yield loss of susceptible cultivars varies with the number of aphid-vectors landing on soybeans in different years. The number of aphids alighting on soybeans and trapped with "green-pan trap" considerably corresponded to the fregnency of their occurrences in the soybean fields during the growing seasons of the last five successive years. A series of epidemic experimental plots which have different seed-transmission rates of SMV were established in Harbin of Heilongjiang province during the growing seasons in 1986～1990. Susceptible cultivars of soybeans were planted. The critical level of seed-transmission rate was 0.5% in 1988, a year of low intensity of aphid-vectors (maximum landing number of alate aphids caught in a green-pan trap in the soybean field was less than 300 from June 20th to July 19th). It was 0.2% in 1986, a year of low-moderate intensity of aphid-vectors (the landing number of alate aphids was 300～600), and 0.1% in 1987, a year of moderate intensity of aphid-vectors (the landing number of alate aphids was more than 600 to 1 200). In 1990 and 1989, the critical levels of seed-transmission rates were 0.04% and 0.01%, because of their moderate-high intensity and high intensity of aphid-vestors (the landing numbers of alate aphids were 1 200 to 1800 in 1990 and 1 800 to 2 400 in 1989). The upper and the lower limits of the critical levels of seed-transmission rates were 0.5% and 0.005%. It can be determined what critical level will be accepted in planting the seeds for controlling the damage caused by SMV, according to the prediction of the aphid-vector intensity.