Добірка наукової літератури з теми "Dianella revoluta"

Restoration is vital for the re-establishment and maintenance of biodiversity of temperate grassy woodlands, but limited understanding of species’ reproductive biology restricts the efficiency of restoration practice. The present study aimed to explore germination cues and seed dormancy of Dianella longifolia R.Br., Dianella revoluta R.Br., and Stackhousia monogyna Labill., three native Australian forb species that have been difficult to germinate in large-scale restoration projects. A series of experiments investigated the effect of various dormancy-alleviation or germination-promoting treatments on germination of these three species. Significant interactions were found between some treatments and germination temperatures for D. longifolia and S. monogyna, but no significant interactions were observed for D. revoluta. At optimal temperatures, scarification treatment produced the highest mean germination for D. longifolia and S. monogyna, and this was significantly higher than for control seeds. Storage conditions (ambient, dry, frozen) did not decrease viability after 10 weeks of storage, suggesting that seeds of all species are likely to be orthodox. To maximise the effectiveness of seed use in restoration programs, it is recommended that scarification of D. longifolia and S. monogyna seed be undertaken to improve field germination. Further work should focus on how to scale up application of the scarification treatment, optimise methods for alleviating dormancy in D. revoluta, and examine the ecological cues that naturally alleviate dormancy and promote germination of these three species.

A novel naphthol-naphthoquinone dimer (5), presumably biosynthetically derived from the oxidative coupling of dianellidin (2) with stypandrone (4) or by the incomplete oxidation of stypandrol (I), has been isolated from the plants Stypandra imbricata and Dianella remluta. The structure was elucidated by spectroscopic techniques and confirmed by its chemical modification to form dianellinone (3).

We used pollinator observation, flower manipulation, controlled pollination and pollen-tube analysis to better understand the reproductive ecology of Dianella revoluta R.Br., a common species known to have depressed fruit set at fragmented sites. This buzz-pollinated species was found to receive large quantities of self-pollen even during a single pollinator visit, but is only partially self-compatible. This may be the first direct demonstration of pollinator-facilitated, autogamous self-pollen transfer accounting for a significant proportion of stigmatic pollen load. Frequent high self-pollen transfer may account for the observed low rate of fruit development in open-pollinated flowers. Self-pollen tubes reached the base of the style in comparable numbers and at the same rate as outcross pollen tubes, with no sign of pollen-tube competition favouring outcross pollen. Barriers to greater self-fertility occur late, probably through early abortion of selfed ovules. We also investigated what impact overlapping distribution with D. longifolia may have on D. revoluta pollination and reproduction. Although these species shared pollinators, they differed in terms of frequency of visits. There was also separation of floral phenology within the course of a day.

Perennial wildflower species are important but not well-understood elements in water-wise landscaping that anchors urban water conservation programs in arid climates. Comparative growth and physiological responses to soil substrate drying of three herbaceous Australian ornamental species from habitats of variable moisture regimes were investigated in the context of isohydric and anisohydric behavior. Clonal Orthosiphon aristatus, Dianella revoluta ‘Breeze’, and Ptilotus nobilis plants were container-grown individually and competitively together in two separate studies. In both studies, plants were water-stressed through cyclical dry downs. We measured stomatal conductance (g S), soil water content, and water potential during each study and osmotic adjustment estimated from pressure-volume data and plant biomass at the end of each study. O. aristatus, a rainforest species, fit a general anisohydric model of high water use and more negative water potential during soil drying until stomatal closure and leaf wilting. D. revolata and P. nobilis, indigenous to Australia's dry interior, fit a general isohydric, drought-tolerant model of stomatal closure from water deficits that moderates leaf water potential but through different mechanisms. P. nobilis and D. revolata moderate water use and maintain acceptable aesthetic performance under water stress, suitable for mixed low-water landscape plantings. O. aristatus would not be suitable for low-water urban landscapes, either isolated or in mixed plantings, because of high soil water depletion and wilting.

Plant species conservation relies on their reproductive success and likelihood of population persistence. Knowledge of plant mating systems, particularly the relationship between plants and their pollinators, is fundamental to inform conservation efforts. This knowledge could be critical for prioritising efforts in human-dominated fragmented landscapes such as the world’s biodiversity hotspots, where reproductive success can be compromised due to habitat loss, limited access to pollinators or other factors. Yet, fundamental data on plant mating systems are lacking for many Australian plants. Here we determined the mating systems of native plant species growing in native woodland fragments within Perth’s urban landscape in south-western Australia. We manipulated insect access to flowers and pollen transfer on five locally common native species, then observed floral visitors and examined reproductive success. Hemiandra pungens and Patersonia occidentalis had mixed mating systems with some ability to self-pollinate, whereas Dianella revoluta and Jacksonia sericea were reliant on insects for outcross pollination. The fruits and seeds produced by Tricoryne elatior were too low to draw conclusions about its mating system. The introduced honey bee (Apis mellifera) was the sole visitor to the mixed mating species, whereas native bees visited D. revoluta and J. sericea (one bee species each). Overall, our data suggest that D. revoluta and J. sericea are more vulnerable to fragmentation than H. pungens and P. occidentalis. Although insects contributed significantly to the reproductive output of the two former plant species, our observations suggested low frequency and richness of insect visitors to these urban fragments. More research is required to determine the generality of our findings. A comparative study in larger native woodland fragments would help estimate the effect of fragmentation on insect pollinators and consequences for the insect-reliant plant species.

Type 2 diabetes mellitus (T2DM), driven by overweight and obesity linked to unhealthy diets, is the fastest-growing non-communicable disease in Australia. Considering that food is an important parameter in the regulation of blood glucose response, replacing ‘junk food’ with products that are good regulators of postprandial blood glucose (PPG) may go a long way to reduce the rate of T2DM in Australia. This study was designed to develop new food products that have the potential for use as nutritional preventatives against escalating levels of T2DM within the Australian Indigenous community. Edible portions of eight Australian native plant species namely; Leucopogon parviflorus, Arthropodium strictum, Carpobrotus rossii, Rhagodia candolleana, Typha orientalis, Correa alba, Dianella revoluta and Acacia longifolia were collected from the coast of Warrnambool, Victoria Australia. The plant species were analysed for proximate, minerals, fatty acids and phenolic composition following the methods of the Association of Official Analytical Chemistry (AOAC), Inductively Coupled Plasma Spectometry (ICP), High performance liquid chromatography (HPLC) and gas chromatography/Mass spectrometry analysis (GCMS). Plant species that exhibited significantly high amounts of nutrients, antioxidants and antidiabetic polyphenols were selected for development of potential antidiabetic food preventatives. The developed food products (Acabungi flakes and crackers) were evaluated for acceptability and the cracker was further studied for stability and microbiological load. Its Glycaemic index (GI) was estimated by in-vitro enzymatic starch hydrolysis. All eight plant species were found to be sources of carbohydrates (39.7 - 65.5%), proteins (2.6 - 15.1%), fats (1 - 14.3%), total dietary fibre (1.5 - 17.2%) and contained Ca, Mg, Na and K. The species exhibited consistent antioxidant activity with phyto-components of gallic acid (GA), epigallocatechin (EPC), catechin (CH), epigallocatechingallate (EPG), dihydroquinidine (DHQ), ρ-coumaric acid (PCA) and luteolin (LT). The betacyanin, betanidin 5-O-β-glucoside (BT) was detected in R. candolleana (700 mg/kg) and C. rossi (244 mg/kg) while the alkaloid, Dihydroquinidine (DHQ) was detected in D. revoluta (101 ± 5.7 mg/kg) and T. orientalis (17 ± 7.1 mg/kg). However, not all the compounds were isolated from a single plant species and except for BT, higher quantities of components were extractable in methanol than water (P<0.05). Palmitic, oleic and linoleic acids were the dominant of 10 fatty acids detected in the native species with record quantities of 4.2 - 39%, 12.3 - 39% and <0.5 - 44% respectively. No single species had all 10 fatty acids. The cracker, with a record overall consumer acceptability of 70.5% remained stable and unchanged with no microbial growth after 35-days storage at room temperature under light and in the dark. The cracker contained significant amounts of total dietary fiber, proteins, complex carbohydrates and exhibited a low GI of 47.7. R. candolleana and A. longifolia were found to have high contents of betanin and linoleic acid respectively, two components with potentially wide industrial application. Further studies to determine the antidiabetic mechanism of action of the cracker would shed more light on its potential application.