Greg Moore

Onset and duration of stigma receptivity in Kunzea pomifera (Myrtaceae)

The onset and duration of stigma receptivity in K. pomifera was evaluated by observing stigma peroxidase activity, pollen-tube growth and seed set, following controlled pollination of flowers of different ages. Peroxidase activity was negligible from 1 day before to 4 days after anthesis, increasing to a peak of 65% at Day 13. The percentage of pistils bearing germinated pollen and ovaries exhibiting pollen-tube entry increased when pollen was applied to the stigma from the day before anthesis, to a maximum at Days 6 and 7 after anthesis, respectively, followed by a decline by Day 9. Under greenhouse conditions the optimum pollination period, measured as the level of set seed after pollination, ranged from 2 to 11 days after anthesis. The knowledge of this aspect of the species reproductive biology is of considerable value in controlled pollinations for its improvement as a new crop.

Breeding behaviour of Kunzea pomifera (Myrtaceae): self-incompatibility, intraspecific and interspecific cross-compatibility

To examine breeding system characteristics of the endemic Australian prostrate shrub Kunzea pomifera, artificial hybridisations were undertaken using thirteen different genotypes of K. pomifera, to elucidate: (1) self-incompatibility, (2) intraspecific cross-compatibility in the species and (3) interspecific cross-compatibility with each of K. ambigua and K. ericoides. K. pomifera exhibited very low self-compatibility, with the barrier to self-fertilisation being prevention of pollen-tube growth in the style or ovary. Following intraspecific pollination amongst a number of different genotypes of K. pomifera, 38.4% of pollinated flowers developed fruit; arrest of compatible pollen-tubes in the style, preventing fertilisation, contributes to the low fruit set in this species. Interspecific compatibility was examined between K. pomifera (pistillate parent) and K. ambigua (staminate parent) where seed set per pollinated flower (4.47) was not significantly different from intraspecific crosses (4.66). In crosses between K. pomifera (pistillate parent) and K. ericoides as staminate plant, 0.037% of pollinated flowers produced fruit, with 0.0075 seeds per pollinated flower. Reproductive barriers between these two species were evident in the style of K. pomifera, where the growing tips of the K. ericoides pollen-tubes swelled and ceased to grow.

Does diversity influence soil nitrate, light availability and productivity in the establishment phase of Australian temperate grassland reconstruction?

Summary  The successful conservation and restoration of the temperate native grasslands of south‐eastern Australia is critical to reversing the decline in range and diversity of these threatened plant communities. Yet the goals of high native species diversity and weed management are difficult to achieve in grassland restoration projects. To increase our understanding of whether synergies exist between these goals (i.e. whether early introduction of a larger number of species might improve both outcomes in the reassembly of native grassland), we examined the relationships between plant species number, functional group number and resource use during the establishment phase of direct‐sown grassland. We did this by sowing a representative suite of species (at varying levels of species number and functional group number) into experimental plots and then measuring and analysing the extent to which the newly established assemblages captured available resources, i.e. used soil nitrate, absorbed light and produced biomass (vegetative cover). Statistically significant correlations were common between the predictor variables (species number, functional group number, percentage vegetative cover, plant number, presence of idiosyncratic (dominating) species) and responses (soil nitrate concentration, light reduction or ‘extinction’). Higher diversity was associated with lower soil nitrate, while percentage vegetative cover and the presence of idiosyncratic species best predicted light extinction. The relationship between diversity, and plant biomass (measured as vegetative cover) and plant number was positive in the first year of the study. The diversity/biomass relationship became negative in the second year due to the higher numbers and cover of ‘idiosyncratic’ species. The diversity/plant number relationship also became negative in the autumn of the second year and was reduced to a trend by the winter. We found that lower nitrate and increasing plant numbers and vegetative cover were most strongly linked to increasing species number in the early stages of this study. This suggests that introducing and maintaining high diversity early in a native grassland reassembly or enhancement project will improve the resistance (e.g. to weed) of these communities. At later stages of grassland development, this function may be provided by the more dominating idiosyncratic species. The maintenance of diversity, an important goal in its own right, will therefore necessitate managed disturbances to periodically reduce the vegetative dominance of idiosyncratic species, releasing resources for the diverse range of other species whose early introduction will have allowed them to persist in the soil seed bank or as suppressed rootstocks.

The National Trust of Australia (Victoria), Register of Significant Trees: Now protecting community assets and heritage with smartphone technology

The National Trust of Australia (Victoria) launched the Register of Significant Trees in 1981. This was to record significant trees throughout the State of Victoria in a logical and systematic manner with the aim of improving their management, protecting them and extending their lifespans. Trees could be registered based on criteria including their beauty, cultural and historic significance and scientific merit measured by rarity, unusual form, as a source of rare propagating stock or their resistance to pests or diseases. By 2012, the Register of Significant Trees contained nearly 1200 registered trees or groups of trees and over 22,500 specimens, including Avenues of Honour, which were widely planted in Victoria, especially after World War I. In Victoria, classified trees have no special legal protection, but lists are provided to relevant authorities dealing with roads and water, gas, electricity and communication services and this provides some protection against inadvertent damage. Furthermore, once classified, a level of political protection and moral persuasion sees significant protection given to many specimens. In 2011, The National Trust of Australia (Victoria) launched Trust Trees, an iPhone app that can locate a specific tree or a collection of trees (all trees in a particular local government area using Apple Maps). Each tree appears as a pin on a map that can be selected for information such as botanical details and historical information, photographs of the tree, its dimensions (height, circumference and canopy spread), and its age and condition.

Pollen viability in Kunzea pomifera (Myrtaceae) as influenced by sucrose concentration and storage

In vitro germination of freshly collected pollen was examined for five genotypes of Kunzea pomifera in liquid media with 5% and 10% sucrose. There were no significant differences in germination level between the different sucrose concentrations for each of the genotypes. Pollen-germination levels were significantly different among genotypes, ranging from 7 to 89%. Pollen of one genotype, stored for 12 months at 4°C and 10% relative humidity, was evaluated for germination at intervals over this period, and while significant differences in the levels of pollen germination after different storage periods were found, there was no correlation between germination percentage and storage time. Pollen of the K. pomifera accession Kmt1 stored under such conditions for 370 days was used in controlled pollination with accession Kmt2, resulting in 3.4 seeds per fruit, which was significantly fewer than the 17.2 seeds per fruit when using fresh pollen.