12 resultados para Grevillea robusta (Cunn.)
em University of Queensland eSpace - Australia
Resumo:
Monoculture plantations of Pinus, Eucalyptus and Acacia have been established oil rainforest lands throughout the world. However, this type of reforestation generally supplies low quality timber and contributes to landscape simplification. Alternatives to exotic monoculture plantations are now beginning to gain momentum with farmers and landholders attempting to establish a variety of rainforest trees in small plantations. When compared to the well studied commercial species, knowledge concerning the growth and management of many of these rainforest species is in its infancy. To help expand this limited knowledge base an experimental plantation of 16 rainforest tree species in a randomised design was established near Mt. Mee, in south-eastern Queensland, Australia. Changes in growth, form (based on stem straightness, branch size and branchiness), crown diameters and leaf area of each species were examined over 5 years. Patterns of height growth were also measured monthly for 31 months. Species in this trial could be separated into three groups based on their overall growth after 5 years and their growth patterns. Early successional status, low timber density, high maximum photosynthetic rates and large total leaf areas were generally correlated to rapid height growth. Several species (including Araucaria cunninghamii, Elaeocarpus grandis, Flindersia brayleyana, Grevillea robusta and Khaya nyasica) had above average form and growth, while all species in the trial had considerable potential to have increased productivity through tree selection. As canopy closure occurred at the site between years four and five, growth increments declined. To reduce stand competition a number of different thinning techniques could be employed. However, simple geometric or productivity based thinnings appear to be inappropriate management techniques for this mixed species stand as they would either remove many of the best performing trees or nearly half the species in the trial. Alternatively, a form based thinning would maintain the site's diversity, increase the average form of the plantation and provide some productivity benefits.
Resumo:
Leucopogon melaleucoides, a flowering shrub, is desired by floricultural markets but is difficult to propagate. Seed viability was tested and dormancy mechanisms were studied to develop a commercial propagation system. Although around 56% of seed were viable, germination was completely inhibited unless the endocarp was removed. After-ripened seed (8 months after collection) germinated faster than fresh seed (2 days after collection), but germination occurred over a prolonged period (155 days). Germination of after-ripened seed was promoted with GA(3) or a commercial smoke product containing unknown plant growth regulators. All viable seed treated with GA(3) at 1000 mg L-1 had germinated after 24 days. The results suggest that both a physical and physiological dormancy mechanism occur for this species, with removal of the endocarp and pretreatment with 1000 mg L-1 GA(3) promoting complete germination of viable seed.
Resumo:
Exogenous treatments with cytokinins, such as 6-benzylaminopurine (BA), can delay senescence of some plant tissues. Grevillea 'Sylvia' inflorescences have a short vase life. BA supplied in vase solutions at up to 0.1 mM did not delay senescence of G. 'Sylvia' in florescences. However, BA applied by dipping at concentrations up to 10 mM extended their vase life (longevity). Senescence parameters of relative fresh weight, flower abscission, flower opening, flower discolouration and flower wilting were all suppressed by BA dips. Dip treatment with BA (1 mM) was effective on G. 'Sylvia' in florescences at three different maturity stages.
Resumo:
The morphology of the fruit and difficulties with fruit processing impose major limitations to germination of Persoonia sericea and P. virgata. The mesocarp must be removed without harming the embryo. Fermentation of fruit or manual removal of the mesocarp was effective but digestion in 32% hydrochloric acid (HCl) completely inhibited germination. The endocarp is extremely hard and therefore very difficult and time consuming to remove without damaging the seeds. The most efficient method was cracking the endocarp with pliers, followed by manual removal of seeds. Germination was completely inhibited unless at least half of the endocarp was removed. Microbial contamination of the fruit and seeds was controlled by disinfestation and germination of the seed under aseptic conditions. The results suggest that dormancy in these species is primarily due to physical restriction of the embryo by the hard endocarp.
Resumo:
To characterise the physiology of development and senescence for Grevillea 'Sylvia'. oral organs, respiration, ethylene production and ACC concentrations in harvested flowers and flower parts were measured. The respiration rate of harvested inflorescences decreased over time during senescence. In contrast, both ethylene production and ACC concentration increased. Individual flowers, either detached from cut inflorescences held in vases at 20degreesC or detached from in planta inflorescences at various stages of development, had similar patterns of change in ACC concentration and rates of respiration and ethylene production as whole inflorescences. The correlation between ACC concentration and ethylene production by individual flowers detached from cut inflorescences held in vases was poor (r(2)=0.03). The isolated complete gynoecium (inclusive of the pedicel) produced increasing amounts of ethylene during development. Further sub-division of flower parts and measurement of their ethylene production at various stages of development revealed that the distal part of the gynoecium (inclusive of the stigma) had the highest rate of ethylene production. In turn, anthers had higher rates of ethylene production and also higher ACC concentrations than the proximal part of the gynoecium (inclusive of the ovary). Rates of ethylene production and ACC concentrations for tepal abscission zone tissue and adjacent central tepal zone tissue were similar. ACC concentration in pollen was similar to that in senescing perianth tissue. Overall, respiration, ethylene and ACC content measurements suggest that senescence of G. 'Sylvia' is non-climacteric in character. Nonetheless, the phytohormone ethylene is produced and evidently mediates normal flower development and non-climacteric senescence processes.
Resumo:
Grevillea (Proteaceae) is a native Australian plant genus with high commercial value as landscape ornamentals. There has been limited research on the culture and propagation of Australian native species. The effect of indole-3-butyric acid (IBA) on the rooting of G. 'Royal Mantle' and G. 'Coastal Dawn' in winter, spring and summer was evaluated at University of Queensland Gatton, Southern Queensland in order to determine the rooting ability of this species in different seasons. Both Grevillea cultivars showed seasonal rooting. The more difficult-to-root G. 'Coastal Dawn' had a reduced response to IBA application than G. 'Royal Mantle'. Stem and leaf indole-3-acetic acid (IAA) levels were not different between cultivars, therefore rooting ability between the two cultivars does not appear to be due to the differences in endogenous IAA levels. (c) 2005 Elsevier B.V. All rights reserved.
Resumo:
The longevity of Grevillea 'Sylvia' inflorescences can be very short and is influenced by exposure to ethylene. Gibberellic acid has the potential to delay senescence in some cut flowers by acting as an anti-ethylene treatment. Gibberellic acid was therefore applied to Grevillea 'Sylvia' inflorescences in vase solutions to determine its effects on longevity. Treatments with gibberellic acid did not prolong the longevity of inflorescences or influence 1-aminocyclopropane-1-carboxylic acid concentrations. Treatments at high gibberellic acid concentrations enhanced flower abscission and we therefore conclude that vase-applied gibberellic acid treatments are not suitable for extending the longevity of cut Grevillea 'Sylvia' inflorescences.
Resumo:
Grevillea 'Crimson Yul-lo' inflorescences have cut flower potential, but their vase life is short. End of vase life is characterized by early wilting. The possibility of physiologically mediated stem end blockage was investigated. Hydraulic conductance of 2 cm long stem end segments declined rapidly and remained lower throughout vase life than that of 2 cm long stem segments from immediately above. Recutting daily to remove basal 2 cm stem ends increased solution uptake, delayed declines in inflorescence water potential and water content, and improved inflorescence vase life. S-carvone is a potential inhibitor of wound related suberin formation, via inhibition of phenylalanine ammonia-lyase. Vase solution treatments with S-carvone (0.318 and 0.636 mM) delayed the decline in hydraulic conductance of basal 2 cm long stem end segments and decreases in vase solution uptake and relative fresh weight of cut stems, and extended vase life. Treatments with the catechol oxidase inhibitor 4-hexylresorcinol (2.5-10 mM) also delayed stem end blockage. These findings suggest that stem end blockage in cut G. 'Crimson Yul-lo' stems is physiologically mediated. (C) 2006 Elsevier B.V. All rights reserved.
Uptake and transport of indole-3-butyric acid in cuttings of Grevillea and Australian native species