Beneficial effect of prey-derived N for Drosera indica, a rare carnivorous plant in Taiwan, growing in field and in culture

Beneficial effect of prey-derived N for Drosera indica, a rare carnivorous plant in Taiwan, growing in field and in culture

Drosera indica, a carnivorous plant, is currently listed as a nationally endangered species in Taiwan. Understanding the biology of D. indica can aid in the effective conservation and protection of this species. The percentage of leaf nitrogen derived from prey in field-grown plants and the significance of carnivory in cultivated D. indica were investigated in this study. Carbon ([C]) and nitrogen ([N]) contents and stable carbon (δ13C) and nitrogen isotope (δ15N) values of field-grown D. indica, its noncarnivorous neighboring plants and potential prey were analyzed. The one-isotope, two-source, end-member mixing model, usingδ15N values of potential prey and plant leaves, revealed that D. indica obtained approximately 57% of its leaf [N] from captured prey, indicating that prey is an important source of the supplementary N for the plant growing in its natural habitat. The prey derived N might confer D. indica a significantly higher N content than its non-carnivorous neighboring plants. Cultivated D. indica plants with access to prey had significantly enrichedδ15N values compared to those with prey exclusion, indicating utilization of N from prey. Significant increases in flower number, capsules and seed production, but not in photosynthetic activity and growth, were found in cultivated D. indica in response to prey availability. In conclusion, carnivory contributes a significant amount of nitrogen to the foliage of the plant in its natural habitat but is not indispensable for cultivated D. indica.