BackgroundVetiver grass (Vetiveria zizanioides L.) is widely used in more than 120 countries for land management (e.g. rehabilitation of saline lands). A wild ecotype of vetiver grass was found in southern China in the 1950s, but little is known about its adaptability to saline stress. For the purpose of understanding its tolerance to salinity as well as corresponding tolerance mechanisms, in a greenhouse with natural lighting, seedlings were grown in culture solutions and subjected to a range of NaCl concentrations for 18 days.ResultsCompared to no NaCl treatment, 200 mM NaCl significantly reduced leaf water potential, leaf water content, leaf elongation rate, leaf photosynthetic rate and plant relative growth rate and increased leaf malondialdehyde (MDA) content, but the parameters showed only slight reduction at 150 mM NaCl. In addition, salinity caused an increase in the activity of antioxidant enzymes in leaves. Moreover, increasing NaCl levels significantly increased Na+ but decreased K+ concentrations in both roots and leaves. The leaves had higher K+ concentrations at all NaCl levels, but lower Na+ concentrations compared to the roots, thereby maintaining higher K+/Na+ ratio in leaves.ConclusionsOur results showed that the salinity threshold of this wild vetiver grass is about 100 mM NaCl, i.e. highly tolerant to salt stress. This wild vetiver grass has a high ability to exclude Na+ and retain K+ in its leaves, which is a critical strategy for salt tolerance.

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.