The Environment

The 1990s represented a decade of immense changes in environmental management in New Zealand. This paper outlines the challenges of implementing the widespread reforms started in the 1980s. In terms of the environment, reforms came in the form of a large volume of new legislation and a new system of decentralised planning and management. This paper discusses these changes in the context of a shift toward a new environmental paradigm. Key issues and initiatives of the 1990s are discussed which address sustainability, integration, environmental leadership, and public involvement. Specific strategies are outlined in reference to biodiversity, which has been identified as New Zealand's most pervasive environmental issue. Ongoing challenges for the future include how to better involve stakeholders to incorporate alternative values in decision making.     

Diversity in the wild potato species Solanum chacoense Bitt.

Summary The morphological and isozyme variation was studied in 22 accessions of Solanum chacoense from Paraguay and Argentina. Clear geographic groups were identified through the use of multivariate analyses. S. chacoense from mountain sites in Argentina could be readily distinguished from plains forms from Paraguay, on the basis of several correlated morphological characters. Three isozyme systems, namely phosphoglucose isomerase (PGI), glutamate-oxaloacetate transaminase (GOT) and peroxidase (PRX) were studied using starch gel electrophoresis. The banding patterns indicated that for each isozyme there were several loci, which were polymorphic. A genetic interpretation of one of the PGI loci was made, and indices of genetic diversity and genetic identity calculated. Principal components analysis, cluster analysis and genetic diversity indicated a close relationship between the geographical groups. These results are discussed in the context of in situ genetic conservation.     

Variation in the grass pea (Lathyrus sativus L.) and wild species

Summary Forty-nine accessions of Lathyrus sativus were studied for morphological variation. Data were analysed using Principal Components Analysis and Cluster Analysis. The variation in 14 species of Section Lathyrus was also evaluated in order to ascertain affinities between L. sativus and other species. L. sativus is a highly variable species, and there is a clear distinction between the blue-flowered forms from south-west Asia, Ethiopia and the Indian subcontinent, and the white and white and blue flowered forms with white seeds which have a more westerly distribution. Differences in vegetative parts may be due to selection for forage types. L. sativus appears to be closely related to L. cicera and L. gorgoni, and this relationship needs further investigation.     

Above-ground biomass of seedling and semi-mature Sesbania sesban,a multi-purpose tree species,estimated using allometric regressions

Above-ground biomass production in seedling and semi-mature individual plants of Sesbania sesban varieties were compared to non-destructive measurements of stem allometrics. The results indicate that measurements of stem characteristics (diameter and total height) are suitable for estimating biomass of S. sesban varieties and therefore useful in the selection of particular varieties for inclusion in short-rotation agroforestry systems in arid- and semi-arid regions. Less labour-intensive methods for accurately assessing the productivity of agroforestry species, such as the use of allometric regressions, could significantly increase the number of individual plants that could be screened in any particular trial. A multiple polynomial regression accurately estimated above-ground biomass in all plants ranging in age from six weeks to eighteen months (r ²=0.99;p<0.001).     

Larvicidal Potential of the Halogenated Sesquiterpene (+)-Obtusol,Isolated from the Alga Laurencia dendroidea J. Agardh (Ceramiales: Rhodomelaceae), against the Dengue Vector Mosquito Aedes aegypti (Linnaeus) (Diptera: Culicidae)

Dengue is considered a serious public health problem in many tropical regions of the world including Brazil. At the moment, there is no viable alternative to reduce dengue infections other than controlling the insect vector, Aedes aegypti Linnaeus. In the continuing search for new sources of chemicals targeted at vector control, natural products are a promising alternative to synthetic pesticides. In our work, we investigated the toxicity of a bioactive compound extracted from the red alga Laurencia dendroidea J. Agardh. The initial results demonstrated that crude extracts, at a concentration of 5 ppm, caused pronounced mortality of second instar A. aegypti larvae. Two molecules, identified as (−)-elatol and (+)-obtusol were subsequently isolated from crude extract and further evaluated. Assays with (−)-elatol showed moderate larvicidal activity, whereas (+)-obtusol presented higher toxic activity than (−)-elatol, with a LC₅₀ value of 3.5 ppm. Histological analysis of the larvae exposed to (+)-obtusol revealed damage to the intestinal epithelium. Moreover, (+)-obtusol-treated larvae incubated with 2 µM CM-H₂DCFDA showed the presence of reactive oxygen species, leading us to suggest that epithelial damage might be related to redox imbalance. These results demonstrate the potential of (+)-obtusol as a larvicide for use against A. aegypti and the possible mode of action of this compound.     

Nitric oxide represses the Arabidopsis floral transition

The correct timing of flowering is essential for plants to maximize reproductive success and is controlled by environmental and endogenous signals. We report that nitric oxide (NO) repressed the floral transition in Arabidopsis thaliana. Plants treated with NO, as well as a mutant overproducing NO (nox1), flowered late, whereas a mutant producing less NO (nos1) flowered early. NO suppressed CONSTANS and GIGANTEA gene expression and enhanced FLOWERING LOCUS C expression, which indicated that NO regulates the photoperiod and autonomous pathways. Because NO is induced by environmental stimuli and constitutively produced, it may integrate both external and internal cues into the floral decision.