Extended abstract
Introduction: Gundelia tournefortii (L.) is a species of Irano-Turanian origin belonging to the Asteraceae family. The strongly lignified disseminule from the secondary capitulum on seeds causes certain challenges for the propagation of this plant. This study aimed to evaluate the best methods for breaking seed dormancy to enable large-scale production of Gundelia tournefortii (L.).
Materials and Methods: Initially, the interactive effects of various scarification methods (hot water, hydrochloric acid, scalpel, and sandpaper) with cold stratification (0, 1, 2, and 3 weeks) or GA3 (0, 250, 500, and 1000 ppm) on seed dormancy breaking were investigated in two separate factorial experiments. Subsequently, the combined effect of GA3 and cold stratification on seed dormancy breaking of seeds scarified with a scalpel was assessed in a third experiment.
Results: The results indicated that all scarification methods significantly increased the emergence percentage and growth parameters of plantlets. Cold stratification and GA3 treatments enhanced these attributes more effectively in plantlets grown from seeds scarified with a scalpel or sandpaper compared to seeds treated with acid or hot water. In the first experiment, the highest emergence percentage (77%) was achieved from seeds scarified with a scalpel combined with 3 weeks of cold stratification. In the second experiment, the maximum emergence percentage (77%), plantlet length (17 cm), and the minimum mean emergence time (11 days) were obtained from seeds scarified with a scalpel and treated with 500 ppm GA3. The results of the third experiment showed that the application of GA3 reduced the required duration of cold stratification by approximately 1 week to achieve the maximum emergence percentage, dry weight of plantlets, and the minimum mean emergence time.
Conclusions: The findings demonstrate that Gundelia tournefortii (L.) seeds exhibit a combination of physical and non-deep physiological dormancy. The highest emergence percentage (81.5%) and the lowest mean emergence time (8 days) can be achieved through scarification with a scalpel followed by cold stratification or GA3 treatment.
Highlights:
- The most significant effect on dormancy breaking was achieved through scarification, particularly with a scalpel, which resulted in 60% emergence.
- There was a significant interaction between various scarification methods and levels of cold stratification or GA3 concentrations.
- Applying cold stratification levels or GA3 concentrations to non-scarified seeds had little to no effect on emergence percentage and plant growth.
