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Galápagos tomatoes (Solanum section Lycopersicon) have long interested scientists and plant breeders. Several morphological and physiological characters found in the endemic Galápagos tomatoes have been bred into the cultivated Solanum lycopersicum, making the native plants an invaluable resource for the development of this important global crop. Extensive fieldwork was carried out on twelve islands, old records were confirmed, new records added, but several previously recorded populations of endemic tomatoes could not be confirmed. I collected tomatoes from 12 islets and Islands. Detailed morphometric analysis on c.400 plants and extensive genetic studies on c.1,200 plants were carried out in addition to fieldwork and natural history studies. Observations and experiments were carried out on herbarium specimens, field collected and green house grown accessions. I confirmed the presence of four taxa in the Galápagos Islands – two endemic species S. cheesmaniae and S. galapagense, the latter here described as new, and two introduced species S. pimpinellifolium and S. lycopersicum. Hybrids were found involving all taxa growing in the Galápagos Islands. Of particular interest is an extensive hybrid zone between S. cheesmaniae and S. pimpinellifolium spanning 20km along the Baltra Road on Isla Santa Cruz. Hybridization raises the threat of extinction by introgression and the possibility of the evolution of a serious invasive species. Conservation recommendations are proposed. In addition, a genetic analysis was undertaken of 60 seed bank accessions of all four tomato species from the Galápagos. Again, indications of hybridization were found, raising the potential of introgression within the seed bank collections, occurring potentially during rejuvenation cycles. Furthermore, I propose a new outline for a generic invasive species threat/impact scoring system. Applying this new system I class Solanum pimpinellifolium as an alien invasive species and assess its impact on Isla Santa Cruz in the Galápagos Islands.

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Specificity in mushroom compost was demonstrated to be due to nutrient deficiency. Growth of micro-organisms was inhibited by a lack of suitable nutrients which can be induced by microbial leaching. Growth inhibition could not be explained by the presence of antibiotics or volatile compounds. Addition of readily utilisable nutrients resulted in increased microbial activity in compost, this being correlated with reduced growth of A.bisporus. Specificity was maintained by a number of mechanisms including the production of volatile inhibitors by mushroom mycelium. The products of reactions between phenolic compounds and laccase from A.bisporus to produce inhibitors might also be important in this context. Availability of substrates to micro-organisms and their C:N ratios were important in restricting growth of compost inhabiting fungi. However, A.bisporus was able to synthesise enzymes for substrate degradation at otherwise restrictive C:N ratios. This was attributed to marked biochemical and structural changes within the mycelium. A large number of extracellular enzymes could be induced in A.bisporus suggesting that a wide range of substrates are suitable for degradation. The selective nature of compost was not explained by differences in inoculum potentials of micro-organisms. When considering the effects of competitive saprophytic ability on specificity it was apparent that substrate degradation was of major importance. A microbiological and microscope study of straw through composting and cropping provided some information on the nature of changes in the substrate with time. During composting a significant increase in microbial biomass occurred on straw, this being markedly reduced during spawn run and corresponding with a reduction in numbers of thermophilic micro-organisms isolated from spawn run compost. Quantitative extraction and chromatographic assay revealed that a major proportion of compost was polysaccharide in nature, the greater proportion of this probably being microbial in origin. This appeared to act as a major nutrient source for A.bisporus during spawn run. Close association with humic acid was suggested to explain lack of degradation of this polysaccharide by other compost inhabitants. These results suggest that operations aimed at producing express substrates might consider specificity in the light of the mechanisms proposed in the present study and benefit from the knowledge that bacterial extracellular polysaccharides may serve as efficient nutrient sources for mushroom growth.

Towards the end of the 1650s, John Evelyn (1620-1706) composed a book on gardening, the ‘Elysium Britannicum: or the Royal Gardens’, transcribing a draft into fair copy between 1660 and 1663. The book was never finished, but a good part of the manuscript survives. He composed the work in three books: the first sets out a philosophical frame for the conduct of gardening; the second describes the design of a Royal Garden; the third book is now lost. In the first book, Evelyn presents a vision of Nature that owes something to newly emerging mechanistic ideas, derived from the contemporary revival of classical atomism, but which owes much more to Renaissance Neoplatonic Hermetic ideas which cast Nature as a vital Universal Spirit. As it appears in the Elysium, Evelyn’s syncretic Hermetico-Mechanical speculative physics is underpinned by an ardent experimentalism which emerges time and again in his descriptions of the Royal Garden, and this is in turn informed by his study of the works of Francis Bacon (1561 – 1626). Bringing the Hermetic and Baconian components of Evelyn’s thought to bear on the study of his gardens, this thesis offers interpretations of four garden designs. Two are the theoretical propositions from the ‘Elysium’: the grand universal Royal Garden as a whole, and smaller the smaller Philosophico-Medicall garden within it. Two are realised designs: the gardens at Wotton in Surrey, and Evelyn’s own garden at his home in Sayes Court, Deptford. Evelyn’s imagined Royal Elysium emerges as a contemplative microcosm, an image of the well governed Kingdom, which reflects the mystical harmony of God’s creation; and as a domain which promotes, represents and accommodates the powerful practices of an operative natural philosophy, instituted in accordance with Bacon’s design. The gardens and landscape at Wotton and Sayes Court reflect similar ideas on a more modest scale.

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Potato (Solanum tuberosum) is the third most important crop in the world after rice and wheat. Potato tubers are rich in starch, but also contain minor amounts of phenolic compounds. The chlorogenic acid isomer 5-O-caffeoylquinic acid (5-CQA) is the predominant phenolic acid in potato. The main aim of this study was to investigate the relationship between phenolic content and starch digestibility in vitro and in vivo. Firstly, the effect of 5-CQA on digestion of commercial potato starch by porcine pancreatic alpha amylase (PPAA) was investigated. The results showed that co- and pre-incubation of PPAA with 5-CQA significantly reduced PPAA activity in a dose dependent manner with an IC50 value of about 2 mg mL-1. Lineweaver-Burk plots indicated that 5-CQA exerts a mixed type inhibition as km increased and Vmax decreased. Secondly, in vitro starch digestion was performed on steam cooked tubers from five varieties of potato (Desiree, Mozart, Rooster, Maris Piper and Maris Peer) with varying phenolic content. 5-CQA content of peeled tuber tissue ranged from 10.36 to 29.46 mg 100g-1 dry weight (DW) in raw tubers and 6.51 to 21.24 mg 100g-1 DW in cooked tubers. With the exception of Desiree, 5-CQA levels decreased after cooking. The composition of the tubers in term of dry matter (DM), total starch (TS), free sugars, starch properties (amylose and starch granule structure) were also determined. Significant differences in digestibility by PPAA alone were observed between potato varieties when measured as area under curve (AUC) of glucose released in vitro (p ≤ 0.05). Rooster had the highest and Maris Piper the lowest AUC. Similar results were obtained when an in vitro digestion that simulated gastric (including pepsin) and intestinal (including amyloglucosidase AMG) digestion was used to calculate hydrolysis index (HI) and estimated glycaemic index (eGI). Finally, the digestibility of potato was measured in vivo using steamed tubers from Desiree, Rooster and Maris Piper. Standard glycaemic index (GI) methodology was followed. The results showed that Rooster has the highest GI (120), followed by Maris Piper (109) and Desiree (98). The differences were not statistically significant. Strong and positive correlations were observed between in vivo GI and eGI (p ≤ 0.01). It was observed that estimated glycaemic index (eGI) of cooked potato negatively correlated with 5-CQA (r=-0.91, p ≤ 0.05 ) and in vivo glycaemic response (GI) negatively correlated with TPC and 5-CQA (r =-0.82,-0.91) (p ≤ 0.05) respectively. Principle component analysis indicated that starch digestibility is affected by multiple factors including phenolic, dry matter, starch content, starch granule size and crystalline lamella structure. It appears that the same single factor does not strongly determine digestibility in all varieties.