Evaluation of some varieties of alfalfa, Medicago sativa (L.), for their resistance to the alfalfa stem nematode, Ditylenchus dipsaci (Kühn, 1857) Filipjev, 1936, under laboratory conditions

摘要

The lucerne stem nematode, Ditylenchus dipsaci (Kiihn), is a serious threat for cultivation of alfalfa in Iran (Abivardi and Sharafeh, 1973). According to observations in various other countries crop rotation, and other cultural practices or application of nematicides often give insufficient control or are too costly (Gil, 1961; Sherwood et al., 1957). Therefore, the use of existing resistant varieties, and the development of new ones seem to offer the most promising possibilities of control of this nematode (Grundbacher and Stanford, 1962 a; Hunt et a!., 1972). There already is a considerable number of such varieties, but different factors have limited their value in certain areas. Susceptibility to bacterial wilt (Christie, 1959; Hanna and Hawn, 1965), insufficient adaptation to new environment (Griffin, 1968; Brown and Goodey, 1956), effect of temperature on resistance (Griffin, 1968; Grundbacher and Stanford, 1962 b), presence of the resistant-breaking populations (Allison, 1956; Smith, 1958), and susceptibility to other nematodes (Reynolds, 1955), have encouraged extensive and continuous efforts to combine other characters necessary for agricultural use with resistance to local stem nematode population (Burkart, 1934 and 1937; Gil, 1961; Godeck and Favret, 1965; Hawn, 1966; Lundin, 1967; Sherwood et al., 1967; Smith, 1955). This study, conducted in laboratory condition, was designed to determine: (i) rates of infection and growth of the seedlings after infestation with stem nematodes from a field of alfalfa in Khafr County; and (ii) fate of the nematodes after penetration in fourty two varieties of alfalfa collected in Iran and other countries.