Micropropagation of Salvadora oleoides—An Oil Yielding Tree of Arid Forests

Salvadora oleoides is an ecologically important multipurpose tree of the arid forest that occurs in saline areas of northwest India. The seed of this plant yields non-edible commercially usable oil. Poor seed germination, low seed viability, and increasing industrialization are some of the constant factors which significantly affect the status of the natural population of this plant. Therefore, there is a great need to develop an efficient propagation system using the tissue culture technique. In the present communication, we demonstrate the development of an in vitro propagation system for S. oleoides. Multiple shoots were induced from nodal segments harvested from about 25- to 30- yr-old lopped trees of S. oleoides on MS medium + 0.1 mg L^?1 NAA (Naphthalene acetic acid) + 2.5 mg L^?1 BA (6-Benzylaminopurine) + additives. The shoots were multiplied by (a) repeated transfer of the mother explants on MS medium + 1.0 mg L^?1 BA + 0.1 mg L^?1 NAA + additives and (b) subculturing of shoot on MS + 1.0 mg L^?1 BA + additives. About 84% shoots rooted ex vitro on soilrite within 3–4 weeks when base (4–5 mm) of shoots was treated with 100 mg L^?1 of IBA (Indole-3-butyric acid) for 5 min. The plantlets were hardened successfully in the greenhouse and transferred to the pots and field. To the best of our knowledge, this is the first report of a regeneration protocol for S. oleoides from explants obtained from mature trees. Use of the ex vitro rooting technique for plant production serves as a more economical option as it reduces labor, cost, and time. We suggest that the methods developed and described in this article can be used for large-scale plant production and conservation of germplasm of this tree species.     

Quantifying links between instream woody habitat and freshwater fish species in south‐eastern Australia to inform waterway restoration

1. Removal of instream woody habitat (IWH) is one factor attributed to declines in fish populations worldwide. Restoration of IWH to help fish populations recover is now common; however, quantitative predictions about the outcomes of these interventions is rare. As such, quantitative links between IWH and fish abundance is of interest to managers to inform conservation and restoration activities.
2. Links between instream habitat attributes, especially IWH, and selected fish species of recreational, cultural, and ecological significance were explored at 335 sites spanning eight streams across south‐eastern Australia. Data were collected on fish abundance and length, IWH density and a range of other habitat attributes at a scale that incorporated at least one of each of the major mesohabitat types (functional river elements). The data were analysed using Bayesian hierarchical generalized linear mixed models to examine fish habitat associations and used to make quantitative predictions of responses to future restoration.
3. Strong positive relationships were found between fish abundance and IWH density and the strength of this relationship varied between species and waterways. Murray cod (Maccullochella peelii), a species commonly targeted by IWH interventions, displayed the strongest association with IWH density. River blackfish (Gadopsis marmoratus) also showed a significant relationship with IWH, but this effect was waterway specific. Fish length was only related to IWH for river blackfish. These results may reflect differences in the life histories of these two species. We suggest that differences in habitat association through ontogeny may be more relevant at smaller spatial scales.
4. The results generated in this study can be used to guide waterway restoration and develop quantitative predictions about how fish might respond to IWH interventions across south‐eastern Australia. This approach provides a powerful quantitative framework within which to explore management options and objectives, and to test our predicted responses to habitat restoration.