Enhancing Seedling Growth in Capparis spinosa L. Seeds: Effects of Soaking and Cold Stratification

The caper bush (Capparis spinosa L.), a hardy Mediterranean plant, exhibits remarkable resilience to arid conditions while offering a wealth of medicinal and industrial applications. However, low and inconsistent seed germination has often hindered large-scale cultivation, primarily due to physical and physiological dormancy. This study investigates the effects of various seed soaking durations and stratification times on different germination substrates, specifically sand and paper. Nine caper ecotypes were selected from diverse provinces of Iran. The study included control seeds and evaluated three soaking periods: soaking seeds in tap water at room temperature for ۲۴ hours, ۱۵ days, and ۳۰ days. Additionally, five stratification periods were assessed at ۴ °C for ۷, ۱۴, ۲۱, ۲۸, and ۳۵ days. The results indicated that cold stratification applied over various periods in a sand substrate was the most effective method for breaking dormancy. Among the ecotypes studied, Alborz exhibited the highest germination percentage (۹۱%) following a ۳۵-day cold stratification period. The treatment demonstrated a positive impact on both the germination percentage and the mean daily germination rate. suggesting that cold stratification is the most effective approach to overcoming seed dormancy in caper ecotypes. Furthermore, our findings revealed that sand is the superior substrate for enhancing caper seed germination. The results imply that the incidence of fungal infection in sterilized sand is lower than in paper, and moisture levels are more uniformly maintained during germination. It was also noted that caper plants derived from freshly collected seed do not consistently develop fully, with only approximately ۱۰% of fresh seeds germinating. The reactions of six caper ecotypes to cold stratification indicate that physiological dormancy is the primary factor contributing to the low germination percentage and rate. Additionally, both physical factors (such as the hard seed coat) and physiological factors (including the immature embryo) contribute to seed dormancy in caper seeds. The seed coat and the mucilage layer that developed its surface represent the primary barriers to germination. The responses of six caper ecotypes to cold stratification further confirm that physiological dormancy plays a significant role in low germination percentages and rates. Consequently, low winter temperatures achieved through cold stratification may be critical in facilitating the spread of caper ecotypes in Iran.

کلیدواژه ها:

germination rate ، germination substrate ، Physical dormancy ، Physiological dormancy ، pre-treatment