Seedling Production from Seeds of a Wild Ecotype of Vetiver Grass (<i>Vetiveria zizanioides</i>L.) in Southern China

Vetiver grass (Vetiveria zizanioides L.) is widely used for soil and water conservation, and land management. In practice, all vetiver seedlings are propagated via ramets or tillers, which cannot meet the market demand and would also destroy the original habitat. Most vetiver genotypes flower but do not produce seeds. A wild ecotype of vetiver grass originated in southern China is fertile, but the rate of seed germination is very low. This study aimed to develop a novel method to improve its seed germination and seedling establishment. In the field, the inflorescences of wild vetiver were wrapped using a transparent plastic bag with a pot containing wet soils. The effects of inflorescence bagging and Tween 80 application on seed germination and seedling growth were examined. The results showed that seed development was characterized by low seed setting rate (19.2%), uneven maturity time, easy shedding (more than 95% of spikelets shed off 20 days after flowering), therefore difficult harvest of viable seeds. Bagging the inflorescence with moist soils in pot ensured the mature seeds falling onto the nursery soil surface and absorbing water for germination while the immature seeds continued to grow on the inflorescence. Bigging not only improved seed development and maturity, saved the procedure of seed collection and storage, but also provided a humid micro-environment for seed germination and seedling growth. Tween 80 as a surfactant promoted seed water absorption, germination and seedling growth. This simple and novel method has integrated the procedures of seed collection, storage, germination and seedling establishment, and enables the production of a large number of healthy seedlings. The possible reasons for the degeneration and disappearance of the original population were also discussed from the perspective of the disadvantages of vetiver propagation.

Relationship Between Micromorphological Structure of Leaf Epidermis and Drought Resistance in Callisia repens

[Objectives]To discuss the relationship between left epidermis structures and drought resistance.[Methods]The leaf epidermis of Callisia repens was studied by optical microscope.[Results]The upper and lower epidermal cells of the leaves of Callisia repens arranged closely,and no cell gap was arranged.The morphology of the epidermal cells was hexagonal,few pentagon or heptagon,the equivalent elliptical aspect ratio was 1.20,the vertical wall was straight and there was no stomatal distribution.Compared with the epidermal cells,the morphology of the lower epidermal cells was irregular.The equivalent elliptic aspect ratio was 1.35,and the vertical wall was smooth and curved.The mean oval aspect ratio of the stomatal guard cells was 1.42,the average stomatal density was 11.79/mm 2,and the average stomatal index was 17.21.[Conclusions]These characteristics provide the theoretical basis for the drought resistance of Callisia repens and the ornamental plants as roof greening.