부산대학교 도서관

Oospore production inVicia faba, cv. Metissa, was quantified in the field after plants had been inoculated with a sporangium suspension of a homothallic isolate ofPeronospora viciae f.sp.fabae. Oospores were produced abundantly during the hole growing season from 3 weeks after inoculation on. Oospores were found in all plant parts above soil level, except in the seeds. Most oospores were found in the leaves. Less oospores were formed in leaves inoculated in an older stage than in those inoculated in a younger stage. Towards the end of the season, in August, numbers of oospores in pods strongly increased.Oospore production in leaves of three cultivars, Metissa, Toret and Maris Bead, was studied in growth chambers at 5, 10, 15 and 20 °C at 16 h light. Oospores were formed earlier at higher temperatures than at lower temperatures. The ultimate numbers of oospores produced in leaves were highest at 10 and 15 °C. Similar numbers of oospores were formed in leaves of cultivars Metissa and Toret. In leaves of cv. Maris Bead significant less oospores were produced than in leaves of cv. Metissa and cv. Toret. Total numbers of oospores produced were not related to the level of host plant resistance to downy mildew. The percentage of asexually sporulating leaf area, assessed in a resistance test, was largest in cv. Metissa and smallest in cv. Toret.