Dormancy and impotency of cocklebur seeds II. Phase sequence in germination process

摘要

Interactions of C2H4, CO2, O2and high temperature in stimulating germination of cocklebur (Xanthium pennsylvanicumWallr.) seeds were studied and the phase sensitive to each factor during germination was determined. The combination of CO2and enriched O2, and particularly that of C2H4and enriched O2, much more effectively stimulated germination than CO2and C2H4. At low temperature, however, the cooperation of CO2and enriched O2was lost and only the effect of C2H4in combination with CO2or enriched O2remained.Carbon dioxide stimulated C2H4production and induced germination when it was applied in the first period of water imbibition, corresponding to the passive thrust forming phase. C2H4became effective after the CO2-responsive phase. In contrast, both O2enrichment and high temperature became increasingly effective with the imbibition times. Anaerobiosis applied during the first period of the germination process showed no inhibitory effect, whereas CO2and C2H4were stimulative even under such a condition.