18 research outputs found
Energy Sorghum : An alternative energy crop A Handbook
Increasing world market prices for fossil fuels, driven by limited reserves, growing demand
and instability in producing regions, now render renewable fuels economical. Such fuels are
also a pathway to reducing greenhouse gas (GHG) emissions and mitigating climate change.
The transport sector which is almost totally dependent on fossil fuels, particularly for
powering personal vehicles and trucks, is the most concerned sector. Biofuels, defined as
solid, liquid or gas fuels derived from biomass, are today the only direct substitute for fossil
fuels on a significant scale particularly in transport sector. Biofuels are considered
environmentally friendly because the CO2 emissions they produce during combustion is
balanced by the CO2 absorbed by the plants growth. To be a viable substitute for fossil fuels,
an alternative fuel should not only have superior environmental benefits over the fossil fuels it
substitutes, be economically competitive with it, and be available in sufficient quantities to
make meaningful impact on energy demand, but it should also provide a net energy gain
over the energy invested to produce it and have minimal effect on food security...
{This handbook was elaborated in the framework of the SWEETFUEL project (grant agreement number 227422), supported by the European Commission
Controversial taxonomy of Strumariinae (Amaryllidaceae) investigated by nuclear rDNA (ITS) sequences
Oxalis seeds from the Cape Flora have a spectrum of germination strategies
CITATION: Jooste, M., et al. 2019. Oxalis seeds from the Cape Flora have a spectrum of germination strategies. American Journal of Botany, 106(6):879-893, doi:10.1002/ajb2.1300.The original publication is available at https://bsapubs.onlinelibrary.wiley.comPREMISE OF THE STUDY: Seed germination strategy has profound
ecological and evolutionary consequences, with transitions between
germination strategies receiving renewed recent attention. Oxalis from the
Cape Flora, South Africa, has seeds with two contrasting germination
strategies: orthodox and recalcitrant. The morphological gulf between these
strategies (and potential intermediate morphologies) has been poorly
quantified, with questions regarding their ecological function and evolution.
We reconsidered this binary classification, emphasizing potential intermediate
states.
METHODS: Seed physiological traits were used to assign strategies to 64
Oxalis species. We tested for morphological/phenological signal
corresponding to defined strategies with cluster, principal component, Kmeans
clustering and discriminant analyses.
KEY RESULTS: We show that an intermediate germination strategy does
exist among Cape Oxalis, with two possible morphological groups within
each strategy. These could reflect a continuum of germination states, where an
ancestral orthodox strategy evolved towards a maximally recalcitrant peak,
with a mosaic of intermediate states reflected in extant taxa.
CONCLUSIONS: Environmental factors may affect germination strategy
and distribution throughout the Cape because recalcitrant and intermediate
species are confined to the winter rainfall region. They occupy specialized
niches and may face adverse impacts under predicted climate change (hotter
and drier winters), meriting focused future conservation.https://bsapubs.onlinelibrary.wiley.com/doi/full/10.1002/ajb2.1300Post prin
Origin and diversification of the Greater Cape flora: ancient species repository, hot-bed of recent radiation, or both?
Like island-endemic taxa, whose origins are expected to postdate the appearance of the islands on which they occur, biome-endemic taxa should be younger than the biomes to which they are endemic. Accordingly, the ages of biome-endemic lineages may offer insights into biome history. In this study, we used the ages of multiple lineages to explore the origin and diversification of two southern African biomes whose remarkable floristic richness and endemism has identified them as global biodiversity hotspots (succulent karoo and fynbos). We used parsimony optimization to identify succulent karoo- and fynbos-endemic lineages across 17 groups of plants, for which dated phylogenies had been inferred using a relaxed Bayesian (BEAST) approach. All succulent karoo-endemic lineages were less than 17.5 My old, the majority being younger than 10 My. This is largely consistent with suggestions that this biome is the product of recent radiation, probably triggered by climatic deterioration since the late Miocene. In contrast, fynbos-endemic lineages showed a broader age distribution, with some lineages originating in the Oligocene, but most being more recent. Also, in groups having both succulent karoo- and fynbos-endemic lineages, there was a tendency for the latter to be older. These patterns reflect the greater antiquity of fynbos, but also indicate considerable recent speciation, probably through a combination of climatically-induced refugium fragmentation and adaptive radiation