Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 10, 1997
Publication Date: N/A
Interpretive Summary: Nematodes are microscopic worms that attack plant roots and cause seven billion dollars worth of agricultural losses per year in the United States. Many nematodes are grown in laboratories for use in research designed to offset these losses. In this study, soybean cyst nematode (a parasite that causes yield losses in soybean) was grown in the laboratory to solve the problem of how to obtain the highest numbers of females from lab cultures. Females were counted from two dozen soybean cultivars. The highest numbers of females were produced on cultivars Bass, Williams 82, Kent, Proto and Chapman; the lowest numbers on Lambert and Chesapeake. Some soybean cultivars had a decrease in nematode production during the late fall and winter, even though the nematodes were in the laboratory. It was also found that only 12 petri dishes of females need to be counted for experiments like this; 20 dishes had originally been used. Growing the nematode on a different soybean cultivar for many months did not increase numbers of females produced on that cultivar. It is worthwhile to expend time and effort screening plant cultivars, as H. glycines populations in culture can be more than quadrupled by soybean cultivar selection. The results will be used by scientists developing environmentally safe methods of managing nematode losses.
Technical Abstract: Nematodes reared in monoxenic cultures are used for many research purposes. To optimize numbers of Heterodera glycines produced in culture, female populations were counted on two dozen soybean cultivars from maturity groups 0-8. A strain of H. glycines race 3, maintained on excised soybean root tips of cv. Kent, was inoculated onto 20 petri dishes of each cultivar. The highest numbers of first-generation females per petri dish were produced on cultivars Bass, Williams 82, Kent, Proto, and Chapman; the lowest numbers on Lambert and Chesapeake. Nematode numbers were correlated with soybean maturity group, but because of variation within maturity groups, this parameter cannot be used to select optimal cultivars for nematode production. A diapause period with decreased nematode production occurred on some cultivars. Additionally, it was found that only 12 petri dishes need be counted to determine a 60 female difference per petri dish among cultivars; this information can be utilized during cultivar selection. An attempt was made to increase nematode numbers on another cultivar (CX 366) by rearing the nematode strain on CX 366. However, six generations of cultivation on CX 366 did not increase number of females produced. It is worthwhile to expend time and effort screening plant cultivars, as H. glycines populations in monoxenic culture can be more than quadrupled by soybean cultivar selection.