Dissection and rearing studies of second-year cones disclosed six species of insects associated with the seeds and cones of singleleaf pinyon pine. Those most commonly encountered were: Dioryctria sp. probably albovittella Hulst, Conophthorus monophyllae Hopkins and Pineus coloradensis Gillette. The three remaining species were of lesser importance. These included the gall midge, Asynapta sp., a minor cone pest and two parasites, one of C. monophyllae, Acerocephala atroviolacea Crawford and an unidentified parasite of Dioryctria, of the family Ichneumonidae. D. sp. probably albovittella was regarded as the major insect destroying cones and seeds of P. monophylla in this study. During the 1976 growing season it attained a maximum level of 29 percent infestation. C. monophyllae occurred less frequently in this study, but probably has a higher potential for destruction in years of poor cone crops or high cone beetle populations. P. coloradensis caused negligible damage to seeds and cones, but was encountered frequently. Early in the growing season it infested a maximum of 38 percent of the cones.

Winter wheat stubble and dried plant residue in Conservation Reserve Program (CRP) fields were burned in the fall and spring to evaluate effects on jointed goatgrass (Aegilops cylindrica Host.) seed survival and germination. Laboratory studies were also conducted to determine minimum temperatures and heat duration needed to reduce jointed goatgrass seed viability. Maximum air temperatures attained during various field burns reached from 74 C to over 700 C. Temperatures 2.5 em above the soil surface remained above 400 C for over 10 seconds and above 600 C for 2 to 8 seconds in burning CRP stubble. Results for the winter wheat stubble location were similar with temperatures sustained above 400 C for over 30 seconds. Seed exposure in the lab to 400 and 600 C flames for 1 second reduced germination to 20 and 15 percent, respectively. Germination was reduced to zero with exposures of 10 seconds or more. Oven temperatures of 150 C reduced germination to 85, 57.5, 17.5, 0 and 0 percent for exposures of 20, 30, 60, 120 and 300 seconds, respectively. At 275 C oven temperature germinability dropped to 50% after a 10 second exposure and 0% after a 20 second exposure. Jointed goatgrass plant populations were reduced 54 to 92% after field burning in the spring or fall. Fall burning provided 70 to 85% control of goatgrass the following spring. In non-burned non-disked plots over 90% of emerging plants germinated from seeds on the soil surface. In burned non-disked plots few seeds germinated from on the surface, with 80 to 90 percent of surviving plants having germinated from buried seed. Herbicides provided limited control of jointed goatgrass. None of the herbicides provided greater than 50% control.

The destructive nature of the clover seed chalcid has been known since the latter part of the 19th century. This jet-black Hymenoptera, often called the "chalcis-fly," destroys from 10 to 20 percent of the alfalfa seed in Utah each year. Damage as high as 85 percent has been reported.

One of the limiting factors associated with seed production of alfalfa and certain clovers is a small jet-black wasp commonly known as the clover seed chalcid, Bruchophagus gibbus (Boheman). In alfalfa seed producing areas this insect is often referred to as the alfalfa seed chalcid or the alfalfa seed chalcis-fly. In local areas of Utah, farmers often refer to this insect as simply "the fly."

Reed canarygrass (Phalaris arundinacea) is adapted to low wet lands and survives flooding and periods of drought. Much of the valley bottom land of Utah is flooded during part of the year, yet some of this land is very dry late in the summer. This grass could become an important forage for Utah's valley bottom lands if stand establishment could be assured. Low germination percentages and long germination periods under field conditions often result in poor stands.

High quality seed is of first importance in efficient crop production. Seed is one of the major factors affecting yield and quality of the crop. High quality seed is of adapted varieties, has high gemination, and is free of foreign material and weed seeds. Crop seed containing weed seeds may be the means of infesting farm land with weeds. Such seed is expensive at any price.

The relationship of artificial heating to the germination of seeds has been a subject of more or less interest for the last 75 years. Like other research work, experimenters first had their attention called to the problem largely as the result of innate curiosity. They were interested in the result as measured by germinative power, of the application to seeds of different amounts of heat for varying periods of time, consequently many divergent and sundry experiments were carried out. Seeds of a large number of plants have been subjected to tests and the results recorded. The investigations include the effect of heating seeds in soil, in water, in atmospheres of different relative humidities, in carbon dioxid, in ether, in carbon disulphid and in dry air. Each specific experiment has been associated with various temperatures and with various periods of tiem. It is of interest to note that the actual methods used in determining results are about as diversified as the time and temperature. This thesis presents data showing only the effects of dry heating seed at high temperatures. Therefore in discussion of the literature only that material will be considered which has a direct bearing upon that phase of the heating problem.

The ecology of plant species at Sandford Rocks Nature Reserve (SRNR) was studied. The study site is an important nature reserve that contains relatively undisturbed natural vegetation. It has a mosaic of exposed granite rocks, scrublands and woodlands. The study involved: a description of the structure and composition of the vegetation; the population characteristics of selected Acacia species; aspects of reproduction in Acacia; germination and seedling characteristics of some Acacia and grass species that dominate the reserve; the effect of seed size on germination and seedling characteristics; and, the relationship of seed size to seed coat thickness in selected Acacia species. Five different areas were studied using the point centered quarter method to sample the woody perennial species. Thirteen Acacia species were examined for reproduction characteristics; and in 2 selected Acacia species, the effects of phyllode and/or inflorescence removal on reproduction was investigated. Germination tests were conducted to identify germination characteristics in 8 Acacia and 7 grass species dominant at SRNR. The possible effects of variation in seed size on germination; seedling characteristics; and, seed coat thickness were investigated in Acacia fauntleroyi and Acacia prainii. A total of 85 species from 20 families of woody perennials were collated. All areas were dominated by the Myrtaceae, Mimosaceae and Proteaceae families. There was considerable variability in the structure and composition of vegetation. Most species were present in particular sites and the composition of communities appears to be related to the heterogeneity of the habitat within the reserve. In areas of shallow or rocky soil, vegetation types present include Allocasuarina huegeliana woodland, Grevillea paradoxa low scrubland and Acacia neurophylla medium shrubland. / In a seasonally wet area, vegetation types present include low open grassland; Eucalyptus capillosa (wandoo) woodland; and, Acacia saligna thicket. In deep, dry sandy soil, vegetation types include Phebalium tuberculosum shrubland, Acacia acuminata and Acacia coolgardiensis thickets. On relatively flat areas that gain water from adjacent large granite hills, the vegetation consists mainly of tall, open woodlands of Eucalyptus species. Vegetation types include: medium tall Eucalyptus salmonophloia woodland with Kunzea pulchella shrubland at the periphery of the Eucalyptus woodland. At rock areas, vegetation types present include dense Leptospermum erubescens thicket, low open Acacia prainii and Dodonaea viscosa shrubland. Of the Acacia populations studied, in A. lasiocalyx no recent seedling establishment was observed. It is hypothesised that recruitment occurs in particular periods. As the plants are associated with rock and soils are generally shallow, it appears that recruitment depends on run-off water from the rocks in winter. Continuous recruitment seems to be the pattern in A. prainii with both seedlings and saplings represented. A. fauntleroyi forms relatively small populations; apparently long drought periods (>l00 d) result in mass death and limit its population size. In A. hemiteles, no seedling stage was found, root competition (for water) from associated Eucalyptus species presumably limits its recruitment. Reproductive success of Acacia is affected by rainfall. A wet winter is required to induce flowering and further rain is required after flowering to promote pod development and good seed set. / All Acacia species suffer from drought in the reproduction season, however they differ in their degree of susceptibility. Leaflessness and tree shape also affect Acacia fecundity. Plants bearing more phyllodes produce more flowers and pods, and branches in the upper part of the crown bear heavier inflorescences. In 1998, all Acacia species at SRNR produced mature seed of low weight, with many immature and diseased seed, which gave poor germination. A late spring frost in 1998 is believed to be responsible for limited seed development. In two selected Acacia species, removal of phyllodes reduced the number of pods produced. Presumably, phyllode removal reduces photosynthate produced, therefore the competition among inflorescences (or pods) for resources is more intense and subsequent abortions are likely to occur. All Acacia species studied showed best germination in the cool winter temperature range. Apparently, seeds are adapted to germinate in winter when seasonal moisture is more likely to be available. The best temperature however, varied slightly between species. The grass species dominant in the reserve, except for Aristida contorta, also had more germination in cooler rather than warmer temperatures. The flora of SRNR is similar to typical vegetation of the Southwest. Generally, Acacia species are present only in particular sites, presumably were habitat moisture allows. Seedlings of Acacia species growing in naturally dry areas have greater root: shoot masses than those growing in seasonally wet areas. Biomass partitioning is an apparent strategy to conserve water. Of the 7 grass species, Amphipogon strictus appears to have fastest growth. / Eriachne ovata has greater root than shoot mass, while in all other species, shoot mass is greater than root mass; a characteristic of species that grow well in moist habitats. The longest shoots and roots are in Austrostipa elegantissima, an understorey species of eucalypt woodland. In A. fauntleroyi, the degree of hard-seededness varies between seed sizes. There is a higher proportion of soft seed in smaller seed. Seed of different sizes show some responses to different pre-treatments and incubation temperatures for germination. Larger seeds generally germinate in greater numbers after higher treatment temperatures. The best treatment for small seeds is pre-treatment at 75°C and incubated at 15°C. For medium and large seed, best pre-treatment is at 75°C with incubation at 30°C or soaking in boiling water and incubation at either 15 or 3°C. In A. prainii, seed size; pre-treatment; incubation; and, their interaction all affected germination; larger seeds are more viable. The best treatment to promote germination of A. prainii is soaking in boiling water and incubation at 25°C. In both A. fauntleroyi and A. prainii, larger seeds produce larger seedlings. Seedlings from large seeds have the potential for more rapid pre-photosynthetic growth. Larger, heavier seed has a thicker seed coat. The seed coat of A. prainii is thicker than in A. fauntleroyi; the difference in seed coat thickness is reflected by more soft seed in A. fauntleroyi (35%) than in A. prainii (6%).

In the highlands of the Northern Philippines, a model of long-term relationships between potato farmers and their preferred seed suppliers is proposed. In the absence of any certified seed system that might provide some guarantee of seed quality, farmers prefer to transact with those seed suppliers with whom they have had some favourable prior experience. Such suppliers provide both the best quality seed and, since most farmers must borrow the capital to purchase the seed, the most favourable terms of repayment. As there is much uncertainty in the exchange, the farmer's relationship with their preferred seed supplier is based on trust. However, since the farmer's satisfaction with the exchange cannot be ascertained until after purchase, trust is antecedent to satisfaction. As satisfaction is derived from the economic benefits the farmer obtains, satisfaction will lead to the farmer's desire to maintain the relationship. Satisfaction is enhanced both by the seed supplier's willingness to extend credit and to provide information. As there is much variation between alternative seed supplier's offer quality, satisfaction will result in the farmer becoming more dependent upon that seed supplier who makes the best offer. Furthermore, having provided the farmer with financial assistance, seed suppliers will find that they have constrained their opportunities to use coercive influence strategies, for in the absence of any formal contract, farmer's may readily default on the loan. The use of coercive influence strategies will reduce both the farmer's trust in their preferred seed supplier and the farmer's desire to maintain the relationship. / While trust is more important in the transitional economies, critical problems emerge with the use of standardised item measures and scales developed in the industrial countries. Cultural specific adjustments are necessary to ensure social constructs such a trust are functionally equivalent. However, in the context of long-term relationships where satisfaction is also cumulative, introducing measures of both economic and social satisfaction have the potential to overlap with the generally accepted measures of trust.

This thesis investigated aspects of plant recruitment across an altitudinal gradient of mountain tops in the Victorian Alps, Australia, and provides a baseline for the patterns and processes of alpine plant recruitment in the absence of large-scale disturbance. The patterns in alpine vegetation across the study sites were described in relation to abiotic environmental factors. Temperatures were lower and precipitation was higher at the high altitude sites. The vegetation did not differ significantly between the sites, although sites at low altitudes were shrubbier than those at high altitudes. Analysis of the soil seed bank revealed high mean densities of germinable seed (80 to 1400 seeds m-2) across the gradient of sites. The similarity between the seed bank samples and the standing vegetation was low (qualitative similarity: 0.08 to 0.2; quantitative similarity: 0.03 to 0.19). In laboratory germination experiments, I found rapid and substantial germination. Final percent germination was above 90% for most species. One species, Aciphylla glacialis, showed evidence of dormancy mechanisms. In subsequent experiments, I found that innate primary seed dormancy in this species could be broken with cold-wet stratification. There were no significant patterns in natural seedling recruitment across the altitudinal gradient. Similarities between the seedling flora and the standing vegetation were low (qualitative similarity: 0.18 to 0.45: quantitative similarity 0.04 to 0.09). Mean seedling density was best predicted by a combination of soil wilting point, altitude and plant litter. In some cases, seedling density was greater than 80 seedlings m-2. The relative importance of either negative (competitive) or positive (facilitative) interactions between seedlings with adjacent vegetation were investigated in relation to seed germination, seedling growth and seedling survival. Facilitative interactions were common at the higher altitude sites. At lower altitudes, facilitative and competitive interactions were common. Without close neighbours at high altitudes, seedlings were unlikely to survive into their second year. An understanding of plant recruitment can provide a useful basis for predicting species responses to large-scale disturbance and climate change.