Paspalidium

Abstract: Molecular phylogenetic analyses using the chloroplast marker ndhF and a single copy nuclear marker, knotted1, show that the panicoid grasses bearing sterile branches (bristles) in their inflorescences form a monophyletic group. The genus Cenchrus is monophyletic, and monophyly of Pennisetum cannot be ruled out. Setaria is not monophyletic, either as a whole, excluding the palm-leaved species from section Ptychophyllum ,o r excluding various uncertainly placed species such as S. grisebachii. There is also no evidence that Setaria and Paspalidium form a monophyletic group. The Australian genera Zygochloa, Spinifex, and Pseudoraphis are placed in the 'bristle clade', confirming that inflorescences of these grasses are homologous with the inflorescences composed of spikelets and sterile branchlets (bristles). Comparison of the nuclear and chloroplast gene trees identifies several taxa as tetra- or higher polyploids; these are confirmed by southern hybridization. In particular, the Australian species of Paspalidium are allopolyploid, a novel and unexpected result. Zuloagaea bulbosa, a species that lacks the synapomorphic bristles in its inflorescence, is confirmed as a morphologically anomalous member of the clade, and is clearly allopolyploid. This study demonstrates the utility of knotted1 as a phylogenetic marker; we show that it is single copy in diploid taxa and that it exhibits adequate variation to distinguish closely related species. Interestingly, inflorescence morphology correlates only partially with relationships suggested by either nuclear or chloroplast trees, suggesting that inflorescence form is easily changed over evolutionary time.

Abstract: A total of 62 perennial grasses were evaluated for herbage production under low-fertiliser conditions at eight sites in the temperate zone of southern Australia from 1999 to 2001. A brief assessment of relative preference ranking by sheep was also made at the end of the experimental period. Four sites were in the high rainfall areas of south-east Australia, two in the drier mixed farming areas of western NSW, and two sites in Mediterranean southern Australia. Seven standard cultivars were included in the comparisons. Plants were grown from seed in glasshouses and transplanted to the field as spaced plants at 6–8 weeks age. Plants were harvested at irregular intervals by clipping to determine herbage production. Relative preference was determined by enclosing sheep in the experimental area at high stocking rates and estimating the amount of herbage grazed after 1, 3 and 5 days. Herbage production data were analysed using a multi-environment trial approach in which the environments comprised all combinations of sites and sampling times over the 3-year period. Overall, 73.6% of the total genetic variation for herbage production was accounted for. Average seasonal comparisons revealed good herbage production from Eragrostis curvula cv. Consol in both winter and summer, but in spring, several Dactylis glomerata lines were the most productive. Consol was not generally preferred by sheep, while D. glomerata lines were. Apart from cv. Consol, C4 species, including Bothriochloa macra, Chloris truncata, Enteropogon acicularis and Dichanthium sericeum had low herbage production in winter and spring, and had low acceptability to grazing sheep. These particular grasses were also not highly ranked for production in summer, although other C4 lines, notably selections of Themeda australis, Paspalidium jubiflorum and P. constrictum were. Few native C3 grasses had superior herbage production, although selections of Elymus scaber, Austrodanthonia fulva and A. duttoniana showed good growth rates. When considering further evaluation, grasses with very high recruitment (e.g. A. caespitosa) may need to be included, and the acceptability of grasses to sheep should also be assessed.

Abstract: The semiarid areas of Manabi province in Ecuador are notably decertified due to overgrazing for animal production. In this study, a selection of the best alternative plants as food for livestock using the entropy-weight method, which is based on Shannon entropy theory, is developed. The entropy-weight method was applied to calculate the criteria weights; and then, the studied plants were ranked according to results of a pondered sum. The selection criteria were plant size (C1), dry material (C2), crude protein (C3), and crude fiber (C4). The possible plants were previously identified by their capacity to adapt to semiarid areas. The results shown that the best five plants were Anthyllis vulneraria, Imperta cylindrical, Cynodon plectostachyus, Bothriochloa pertusa, and Paspalidium desertorum, in that order. In the future, these selected plants could be cultivated experimentally; and then, according to the results, they could be considered as an alternative to resolve the food problem for livestock, or to recuperate the decertified areas in Manabi, Ecuador.

Abstract: Synflorescences of the Australian species Paspalidium rarum (R. Br.) Hughes are described. Their structure in relation to other species of Paspalidium is discussed and their significance as an intermediate step in the evolution of inflorescences of Poaceae is considered. Such inflorescences comprise raceme-like structures which are derived from the typical inflorescences of Paspalidium by strong apical reduction of lateral axes. They possess two successive distal homogenised zones, the upper one bearing first-level short paracladia and the lower bearing truncate second-level short paracladia, and a proximal non-homogenised zone bearing more or less apically reduced long paracladia. The presence of such structures suggests a possible evolutionary pathway by which inflorescences such as those of Chloris, Cynodon, etc. could have evolved.