Restoration and rehabilitation activities are presently considered to be a major priority in environmental management, whether the activity implies the restoration of neglected cultivated pastures or degraded rangelands due to overgrazing and climatic impacts, or the rehabilitation of the mining and industrial areas. However, the goals are not easily achieved, mainly due to the high input costs, including that of re-seeding activities. Reseeding success is influenced by the quality and effectiveness of the used seed regarding germination and establishment under natural field conditions. If techniques can be developed to enhance the effectiveness of germination and establishment percentage of the seed in restoration and rehabilitation sites, a better cover, density and biomass yield can be expected, which will improve the rehabilitation process. It is known that commercially available grass seed has a better germination percentage and establishment percentage in comparison with seed locally harvested, which may include many impurities such as sticks and stones. The availability of the locally harvested seed types, especially of certain ecotypes adapted to specific environments, can be poor. Advance Seed Company (Krugersdorp, South Africa) has taken commercially available grass seed to the next level by enhancing (coating) the seed with a multitude of different treatments to ensure better handling of the seed in reseeding applications. These treatments also have advantages such as a higher seed to soil contact, growth stimulants included in the treatment, higher seed purity and the protection of the seed against predation by ants and other insects and against harsh chemicals in the soil, which might have an influence on the germination percentage of the seed and the establishment of seedlings. The objective of this study was to investigate whether or not certain enhanced grass seed types of selected grass species will have a better germination and establishment percentage, fresh and dry above-(leaves) and below-ground (root) biomass yield (glasshouse trials) and dry above-ground biomass yields (natural fields trials) in comparison with non-enhanced types. The predation of enhanced and non-enhanced seeds by ants and other insects, as well as the development of the vascular tissue in the transitional region of the seedlings was also investigated. The grasses assessed included enhanced and non-enhanced seed types of Chloris gayana (Rhodes grass), Cynodon dactylon (Couch grass), Digitaria eriantha (Common finger grass) and Eragrostis curvula (Weeping love grass). In the case of E. curvula, four seed types, including the non-enhanced seed type were tested. These included non-enhanced seed, seed treated with "plain coat", enhancement with "organic insecticide on the base of the coaf' (Le. insecticide between the enhancement and the seed) and enhancement with "organic insecticide on the base of the coat and as an overspray" (Le. insecticide between the enhancement and the seed, as well as spraying the insecticide over the coated seed). The above mentioned species are commonly used in grass seed mixtures for rehabilitation and restoration purposes. Seeds were supplied by Advance Seed Company. The seed enhancement treatments as well as the non-enhanced seed types were tested under various conditions. The chemical composition of the enhancement treatment used in the coating process is only known by the seed technicians at Advance Seed Company. All the seed supplied by the seed merchant had a purity of >95%. With the application of dormancy breaking in the germination tests the non-enhanced seed types of Chloris gayana had the higher germination percentage of the seed type or the same species. Other differences included the germination percentage being significantly higher for the enhanced seed type of Cynodon dactylon than the non-enhanced seed type. Lower germination percentages were noted in the comparison of the E. curvula seed types, were the non-enhanced seed type had a higher germination percentage in comparison with the enhanced seed types. In the germination tests without dormancy breaking being applied, these results differ. With regard to the establishment percentages, similar statistical differences were noted in both the Coco Peat Moss medium and the Hygromix growth medium. In the above-and below-ground biomass production trials in the glass house the only significant difference were noted in the biomass production of D. eriantha plants. In the case of the dry above-and below-ground biomass yield the plants of the non-enhanced seed types of D. eriantha yielded a significantly higher biomass in comparison with the plants harvested from the enhanced seed type of the same species. With regard to the natural field trials a few significant differences were noted. The results indicated that the enhanced seed types of Chloris gayana and Cynodon dactylon, the non-enhanced seed type of D. eriantha as well as the non-enhanced and "organic insecticide on base and as overspray" enhancement of E cUNula can be used in re-seeding restoration and rehabilitation practices. Eragrostis cUNula enhanced with "plain coat" is not recommended to be used for re-seeding in disturbed areas. / Thesis (M.Sc. (Environmental Science and Management))--North-West University, Potchefstroom Campus, 2008.

Univ., Diss.--Wageningen, 2004.

Thesis (Ph.D.)--Wageningen University, 2004. / Thesis propositions inserted. Includes bibliographical references (p. 341-366).

Thesis (Ph. D.)--Wageningen Universiteit, 2005. / Thesis propositions sheet inserted. Includes bibliographical references (p. [249]-262).

Master of Science / Genetics Interdepartmental Program / Eduard D. Akhunov / The CRISPR/Cas9-based genome editing system holds a great promise to accelerate wheat improvement by helping us to understand the molecular basis of agronomic traits and providing means to modify genes controlling these traits. CRISPR/Cas9 is based on a synthetic guide-RNA (gRNA) that can guide Cas9 nuclease to specific targets in the genome and create double strand breaks (DSB). The DSB are repaired through the error-prone non-homologous end joining process causing insertions or deletions that may result in loss-of-function mutations. Here, we have developed an effective wheat genome editing pipeline. We used next-generation sequencing (NGS) data to estimate genome editing efficiency of many gRNAs using the wheat protoplast assay and choose the most efficient gRNAs for plant transformation. We successfully applied this pipeline to five wheat orthologs of the rice yield component genes that have been identified previously. We obtained edited plants for all these genes and validated the effect of the mutations in TaGW7 on wheat traits, which showed trends similar to those in rice. These results suggest that transferring discoveries made in rice to improve wheat is a feasible and effective strategy to accelerate breeding.

Abstract The aims were to examine the importance of regeneration by seeds, the influence of plant traits and disturbances, and the role of seed-seedling conflicts in regeneration and in the determination of vegetation structure. The study was carried out at in a subarctic alpine area (Kilpisjärvi 69°01'N 20°50E', Finland). Seed bank and seedling densities were high in many plant communities (ranges 99 -1109 viable seeds/m2 and 0.2-227 seedlings/m2, respectively). Effective seedling recruitment is reflected in vegetation as a high proportion of plants with poor or no vegetative reproduction ability. This development may take place in meadows and snowbeds where herbs (e.g. Gnaphalium supinum, Sibbaldia procumbens, Veronica alpina and Viola biflora) are abundant. On the other hand, the low proportion of these plants in heath vegetation reflects ineffective seedling recruitment. Floristic similarities between the consecutive phases in the regeneration pathway may be low despite effective seedling recruitment. Clonality, large and small seed sizes and appendaged diaspores limit the movement of species from phase to phase. Generally, disturbances facilitate effective regeneration by seeds. Grazing promotes species with large seed banks and is therefore one reason for high seed bank densities. Freezing and melting processes negate a negative influence of altitude on seed bank densities in the phase of seedlings. However, if disturbances are severe and continuous and the soil is compact, unstable or dry, disturbances are not beneficial. The same is true if there is a shift in the species composition of seedlings from gaps to closed vegetation. This phenomenon occurred in a rich meadow. Seed-seedling conflicts limit regeneration by seeds in low-herb snowbeds and Ranunculus glacialis-Gymnomitrion snowbeds. Vegetative reproduction and infrequent pulses of seedling recruitment negate an influence of short-term seedling recruitment on the spatial structure of vegetation. Extreme conditions, such as low temperatures, instability of the soil and late snowmelt modify the influence of factors that are important in more moderate conditions. To conclude, all transitions limit regeneration by seeds. However, favourable conditions (e.g. moist conditions in a meadow) partly eliminate the obstacles against seedling emergence. Regeneration by seeds therefore has a major impact on the dynamics and structure of vegetation. In heath vegetation, where bare soils are dry and the moss cover is thick, large seed banks and seed rains do not guarantee effective seedling recruitment. The regeneration process is reduced in the early phases, and plants that reproduce primarily by seeds have a minor role in vegetation. The accumulation of seed banks is effective in these circumstances.

Fungicides have been developed to protect plants against diseases and pests, which cause serious problems such as the loss of germination and vigour. The aim of this study was to test the germination and vigour of maize (Zea mays L.) seeds treated with several fungicides Apron® Star 42 WS (difenoconazole, thiamethoxam, and metalaxyl-m), Apron® XL (mefenoxam), Celest® XL (fludioxonil, mefenoxam) and thiram in the laboratory. In the greenhouse, the efficacy of fungicide treatment was evaluated in soil inoculated with Fusarium graminearum. The control consisted of untreated seeds. Germination and vigour were evaluated according to the International Seed Testing Association (1ST A) rules. The results from the standard gennination tests showed that all the fungicide treated seeds did not differ to the untreated control. The conductivity of solute leakage was read following slow and fast imbibition. Maize seeds treated with Apron® Star 42 WS, Celest® XL, Apron® XL and thiram improved or maintain vigour, which was indicated by a reduced or equivalent solute leakage following fast imbibition when compared with the untreated control. The good performance of fungicide treated seed expressed during conductivity test after fast imbibition correlated with the tetrazolium. All the fungicide treated seeds maintained the same viability as the untreated control following fast imbibition. After 6 h after fast imbibition, Apron® Star 42 WS, Celest® XL and Apron® XL treated seeds maintained similar germination percentages when compared to the untreated control with the exception of thiram treated seeds that exhibited a decline in seed viability. There was reduction in vigour in all the fungicide treated seeds fo llowing 24 and 40 h fast imbibition as illustrated by the reduction in germination percentage below the acceptable level (70%) when compared with the untreated control. The greenhouse study showed that all the fungicide treated seeds maintained the same emergence percentage in both inoculated and uninoculated soil with the exception of thiram treated seeds, where emergence improved in inoculated soil when compared to the untreated control. Apron® Star 42 WS and Celest® XL reduced the disease caused by F. graminearum in the inoculated soil. This study also revealed that the application of Apron® Star 42 WS, Celest® XL and thiram to seeds improved both the shoot and root dry mass of plants in the inoculated soil. / Dissertation (MInstAgrar)--University of Pretoria, 2011. / Microbiology and Plant Pathology / unrestricted

Doctor of Philosophy / Department of Plant Pathology / Christopher R. Little / Fusarium spp. are among the most important pathogen groups on soybeans. However, information regarding this genus on soybean seeds in the state of Kansas remains underexplored. Therefore, the goal of this study was to characterize the identity, frequency, and pathogenicity of soybean seedborne Fusarium spp. in the state of Kansas. For the identification and frequency of seedborne Fusarium spp., culture-dependent (i.e. semi-selective medium) and -independent (i.e. DNA metabarcoding) approaches were used. Also, information regarding the pathogenicity of the most common seedborne Fusarium spp. from soybeans was assessed to better understand their role as soybean pathogens. Overall, eleven Fusarium spp. were identified in this study. Semi-selective media showed that approximately 33% of soybean seed samples were infected with Fusarium spp. Moreover, Fusarium spp. were isolated from seed sampled from 80% of the locations in Kansas. Furthermore, a low incidence of Fusarium spp. was observed within infected seed samples and averaged 2%. Nine Fusarium spp. were found in soybean seeds using the culture-dependent approach. Fusarium semitectum was the most frequent, followed by F. proliferatum and F. verticillioides. Fusarium acuminatum, F. equiseti, F. fujikuroi, F. graminearum, F. oxysporum, and F. thapsinum were found in lower frequencies among naturally infected seeds. DNA metabarcoding experiments showed that Fusarium spp. are more frequent in soybean seeds than previously known. All asymptomatic soybean seeds analyzed, using Illumina MiSeq platform, showed the presence of the genus Fusarium including two pathogenic species, F. proliferatum and F. thapsinum. Fusarium acuminatum, F. merismoides, F. solani, F. semitectum, and Fusarium sp. were also identified using the culture-independent approach. Preliminary results also showed that F. proliferatum and F. thapsinum were observed in all three major soybean seed tissues: seed coat, cotyledons, and the embryo axis. Depending on the soybean genotype, inoculum potential and aggressiveness, F. proliferatum, F. graminearum, F. fujikuroi, F. oxysporum, F. semitectum, F. thapsinum, and F. verticillioides were pathogenic to soybean and negatively affect soybean seed quality, at different levels, in controlled conditions. Moreover, F. equiseti and F. acuminatum did not cause significant damage to soybean seeds and seedlings. Understanding seedborne Fusarium spp. and their influence on soybean seed and seedling diseases is critical for the development of effective disease control strategies, especially regarding early detection of pathogenic strains in seeds (i.e., seed health testing), ensuring the crop productivity, quality, and safety.

The main objective of this research was to determine the seed bank longevity of Melinis repens at two Southern Florida sites. Seeds were divided among different exposure levels (shade versus sun) and depths (surface versus buried) and tested for baseline viability using 2,3,5-Triphenyl-tetrazolium chloride. Statistical analysis determined that at the pine rockland site there was a significant interaction between time, exposure, and depth. The initial mean viability at this site declined from 49.71% to 11.26% and 13.06% for sun/buried seeds and sun/surface seeds, respectively, by month 8. The mean viability of shade/surface seeds and shade/buried seeds declined to 24.56% and 22.06% after 8 months. There were no significant effects in the Florida scrub. In order for land managers to completely remove this species from a site, treatment with herbicide will need to continue for a minimum of one year to effectively kill all viable seeds in the seed bank.

The objective of the first chapter of this thesis was to determine whether fungicide seed coatings constitute an effective strategy for increasing seedling recruitment in restoration scenarios in the Intermountain West. We tested a mixture of four fungicides that address potential fungal pathogens to bluebunch wheatgrass, a dominant bunchgrass that is commonly used in restoration. Across two sites and three years, we found that the fungicide seed coating increased emergence in five of the six sites and years, with an average increase of 59.1% over the control. There was a strong interaction (P < 0.001) between the effects of fungicide treatment, the year and the site on emergence. This interaction was likely related to the effects of the hydrothermal microsite environment on disease severity. Further research is necessary to fully understand the conditions under which fungicide seed coatings are most likely to be effective. The objectives the second chapter of this thesis were to 1) estimate the effects of golden eagle nest proximity to explosive disturbances on reproductive success given other relevant habitat variables (e.g. indices of topography and vegetation), and 2) determine the relative importance of nest proximity to explosive disturbances as a predictor of golden eagle reproductive success compared to other relevant habitat variables. Reproductive success data were collected from nesting territories within and surrounding land controlled and managed by the US Department of Defense. We fit the reproductive survey data using generalized linear mixed-effects models comprised of unique, hypothesis-based sets of habitat variables. We compared the models using AICc-based model selection processes. Given the best approximating model, we found no evidence that the likelihood of reproductive success was affected by nest proximity to explosive disturbances (P = 0.460). We further found nest proximity to explosive disturbances consistently ranked in the bottom 50% of relative variable importance. These results may indicate golden eagle tolerance or habituation to explosive military tests and trainings. Although the two chapters of this thesis are disjointed, they are loosely unified by the ecological importance of disturbance, invasive species, and restoration within the Great Basin ecoregion.