The occurrence ofFusarium andAlternaria on faba bean seed
The studies on the occurrence ofFusarium andAlternaria in faba bean seed have been conducted for three years. The fungal flora in seed lots from healthy plant and from plant inoculated withAscochyta fabae were determined. In addition the occurrence ofFusarium andAlternaria in three parts of seed: testa, cotyledones, and embryo axis were investigated.It was found thatFusarium andAlternaria were present in faba bean seed, but the frequency of occurrence varied depending upon cultivar and experimental year.
Fungus diseases of field bean in Finland during 1975-1977.
During 1975 1977, studies were carried out on the fungus diseases of field bean and attempts were made to find, through seed-dusting trials, suitable methods for their control. The fungal flora in a total of 43 seed lots containing 140 200 seeds each were determined. In addition, plant samples collected from farms where field beans were under cultivation and field bean cultivar trials in seven localities were analysed. The weather conditions in the growing seasons of 1975 and 1977 were rather exceptional, the former being dry and warm and the latter rainy and cool. Ripe crops were obtained from the control experiments, in which the seeds of 3—4 field bean cultivars were dusted with thiram and benomyl preparations, only in 1975 and 1976. Ascochyta fabae Speg. was rare in all the seed samples apart from those from LänsiHahkiala, where the degree of infection varied, depending on the cultivar, from 1.3 20 %. Botrytis fabae Sard, was rare in the seeds, B. cinerea Pers. ex Fr. quite common in 1976 and especially in 1977. The frequency of the Fusarium fungi were very great on the seeds in 1977, F. culmorum (W. G. Sm.) Sacc. and F. avenaceum (Fr.) Sacc. being the most common. A. fabae was quite common in the stand samples collected at Länsi-Hahkiala in 1975 and 1976. The chocolate spot-causing agents, B. fabae and B. cinerea, were relatively rare in all years except 1977, when some cultivars were heavily infested by B. cinerea.
Inhibition of Root Growth and Polyamine Metabolism in Sunflower (Helianthus annuus) Seedlings Under Cadmium and Copper Stress
Although sunflower is usually regarded as a highly tolerant crop, impairment of root growth at initial stages of plant development may result in poor crop establishment and higher susceptibility to pathogen attack. In order to evaluate if Cd2+ and Cu2+ may impact on sunflower germination and initial root development, a pot experiment under controlled conditions was carried out. Possible involvement of polyamine metabolism in sunflower response to these stressors was also investigated. Although Cd2+ and Cu2+ treatments affect neither seed germination nor radicle emergence, sunflower seedlings grown in the presence of these heavy metals showed significant inhibition of root growth, being this inhibition greater for Cd2+. Both metals caused significant increases in proline contents at the highest concentrations tested (0.5 and 1 mM), and these increments were more pronounced for Cd2+ treatments, especially between days 3 and 10. Metals also increased putrescine (Put) contents at all concentrations assayed from the seventh day onward, causing no variations on this polyamine time-course pattern. Spermine and spermidine contents, however, were increased only by 1 mM Cd2+. Arginine decarboxylase seems to have been the enzyme responsible for Put increases under both metal treatments. This work demonstrates that initial root growth of sunflower seedlings may be significantly impaired in Cd2+ or Cu2+ contaminated soils. It also shows that polyamines are key biological compounds, which are probably involved in signaling pathways triggered under stress environmental conditions.