Germination and emergence characteristics of triazine-susceptible and triazine-resistant biotypes of Solanum nigrum.
Seedling emergence patterns of triazine-susceptible and triazine-resistant Solanum nigrum plants were studied in the field at Wageningen, the Netherlands. Emergence patterns were similar in the first year, but in the second year resistant seedlings emerged faster and the number of resistant seedlings was higher. To explain emergence patterns, a germination experiment was carried out. Seeds from two populations with triazine-susceptible and -resistant biotypes were buried in late autumn and exhumed monthly during spring. Germination was assessed in incubators at different constant temperatures. The lowest temperatures for germination of seeds from the Achterberg population ranged from 20°C on 1 February to 10°C on 1 May for the susceptible biotype, and from 15°C on 1 February to 10°C on 1 May for the resistant biotype. The lowest temperatures for germination of seeds from the Zelhem population ranged from 25°C on 1 February to 10°C on 1 May for the susceptible biotype, and from 15°C on 1 February to 10°C on 1 May for the resistant biotype. The minimum germination temperature of seeds from the resistant biotype appeared to be lower than that of the susceptible biotype. Emergence patterns in the field could be explained by soil temperature and different minimum germination temperature requirements of seeds from the triazine-susceptible and -resistant biotype. This knowledge can be used to manage triazine-resistant biotypes of S. nigrum by the timing of soil cultivation.