Abstract:

Orychophragmus violaceus is an important ground cover， landscape， and green manure crop species. Seven species of seed-borne fungi in five genera were isolated from the seeds of O. violaceus， and their pathogenicity was determined in seed germination， in vitro leaf inoculation， and greenhouse potted plant tests. The seed-borne fungi were Alternaria alternata， Alternaria brassicicola， Alternaria tenuissima， Epicoccum nigrum， Fusarium incarnatum， Harzia acremonioides， and Ulocladium sp. The percentages of seed rot and seedling rot caused by the seed-borne fungi ranged from 16.50% to 68.50%. A. brassicicola and H. acremonioides caused the seed germination percentage to decrease by 18.18%-27.27%. All the fungi caused symptoms such as chlorosis and leaf rot when inoculated onto O. violaceus leaves in vitro： the disease incidence was 100%， the lesion area was 8.84%-99.38%， and the disease index was 22.50-95.00. In potted greenhouse-grown O. violaceus plants， the seed-borne fungi caused wilt， chlorosis， leaf spot， or leaf rot symptoms. The percentage of diseased seedlings was 100%， the diseased leaf rate was 41.56%-79.88%， and the disease index was 16.22-56.93. We compared various biochemical indexes between control plants （not inoculated with seed-borne fungi） and those infected with seed-borne fungi at 9 days after inoculation. Compared with the control plants， the infected plants showed 30.40%-204.15% increases in malondialdehyde content， -1.81%-82.87% and 18.78%-86.14% increases in peroxidase and superoxide dismutase activities， respectively， and 13.24%-37.85% reductions in SPAD value. The results of the pathogenicity tests showed that A. brassicicola and H. acremonioides had the strongest and weakest pathogenicity against O. violaceus， respectively.

Key words: Orychophragmus violaceus, green manure, seed borne fungi, pathogenicity