International interest in fluidised bed combustion (F.B.C.) derives from the fact that it involves new technology and it is the only combustion system that can use low grade fuels (including those of high or variable ash content) efficiently. This thesis presents a study of the combustion of straw in a fully fluidised and systematically interrupted flow test rig. In the interrupted flow mode, it was found that during the period in the cycle when the bed was slumped, due to the reduction in primary air, a gasification process took place. This resulted in a higher percentage of volatiles being burned in the bed and preliminary results indicated that interruption gave an increase in overall efficiency of approximately 4%. It also led to lower losses being incurred in the flue gases and, to a lesser extent, to a reduction in the losses expected due to incomplete combustion of the fuel. Elutriation and carbon losses were also reduced to 88% and 86% respectively of those recorded during uninterrupted fluidisation. By increasing the area of the zone directly above the fluidised bed, the products of combustion were decelerated sufficiently to ensure that ash was not found on the walls or roof to the same extent as that previously noticed on commercial straight-sided combustion chambers. Small quantities of ash were found in the ducting leading to the cyclone but they were approximately the same for operation in both the uninterrupted and interrupted fluidisation mode.

Wheat (Triticum aestivum L.) is one of the three most important cereal crop grown globally and there is a gap between yield production and world demand. Previous studies on wheat have generally shown traits influencing the capacity of the grains to store assimilate (sink) to be better correlated with yield than traits influencing potential assimilate production (source). Therefore, strategies to improve ear fertility, defined as the number of grains per ear, are one of the most relevant features in the development of new cultivars and genetic improvement of yield potential. In the present study, novel large-ear phenotype (long rachis) is investigated as a trait to increase the number of grains per year, thus grains m", with the aim of identifying physiological processes limiting genetic improvement of ear fertility in wheat. Two advanced lines (NLI and NL2) developed by the International Centre for Maize and Wheat Improvement (CIMMYT) with novel ear morphology and one CIMMYT cultivar with conventional ear morphology Bacanora referred to as the parental spring wheat genotypes were characterized. In addition, 69 doubled-haploid (DR) lines from a cross between NL2 x Rialto (UK-bred cultivar) were used to investigate the physiological basis of improved ear fertility and yield potential in the novel material. Three field experiments were carried out at the CIMMYT experimental station in Cd. Obregon (Mexico) on the parental genotypes (2003/04, 2004/05 and 2005/06) while two field experiments were carried out for the NL2 x Rialto population (2004/05 and 2005/06). An additional experiment consisting of a subset of 15 lines of the NL2 x Rialto population was carried out in 2005/06. Two controlled-environment experiments were carried out at Sutton Bonington, University of Nottingham in 2004 and 2005 to investigate the developmental basis of the large-ear phenotype on the three parental genotypes. A post-anthesis (GS 61+ 14d) degraining treatment was imposed in field experiments examining the parental genotypes in 2004, 2005 and 2006 while a similar degraining treatment was carried out for the subset of 15 DR lines of the NL2 x Rialto population in 2006. A range of physiological traits related to ear fertility were measured on the parental genotypes and the DR lines including rachis length, spikelets ear"1, developmental stages, green area, radiation interception, radiation use-efficiency (RUE), dry matter production and partitioning, stem water soluble carbohydrate reserves, potential grain weight, grain weight and combine yield. In the growth-room experiments, the rate and duration of spikelet primordial production of the main shoots were measured. Present results showed that in the novel genotypes, longer rachis increased spikelets ear" and also grains ear-i. Thus, the novel genotypes showed greater ear fertility by having more grains ear" than the benchmark cultivar Bacanora. Grains m-2 was not actually increased in novel genotypes; indeed lower grains m-2 was found in NL2 compared to Bacanora. Heavier grains were found in the novel genotypes which had greater potential and final grain weight compared to Bacanora. The NL2 genotype possesses a tiller inhibition gene (tin) on chromosome 1A and this genotype had fewer ears m-2 than the other genotypes, and this trait also contributed to the lower grains m-2 ofNL2. The grains-to-ear DM ratio at GS 61 in NL2 was markedly lower compared to other genotypes. Results of the growth-room experiments showed that there was a developmental basis for the higher spikelets ear" observed in NLl and NL2 than Bacanora. A longer thermal duration from floral initiation to terminal spikelet was associated with a higher spikelet number in NL1 (27) and NL2 (29) compared to Bacanora (23). Since the growth-room experiments were carried out under long photoperiod (16 hrs) results also suggested that the large-ear phenotype may have been associated with the effects of 'earliness per se' genes. Grain weight of the parental genotypes did not respond differently to degraining. Averaging across parental genotypes and years, responses to degraining in the field experiments showed that although assimilate supply per grain was potentially increased by 100%, average grain weight was only increased by 15%. These findings indicated that grain yield was mainly limited by post-anthesis sink size in these experiments. In the subset of 15 DH lines experiment, there were different responses of the lines to degraining and the lines which showed larger responses of individual grain weight to degraining had lower grain weight in control intact ears. Results of the DH experiments showed that rachis length was positively correlated with spikelets ear", grains ear" and grains m-2 among the lines. There was also a positive phenotypic correlation between the grains-to-ear DM ratio at GS 61 and grains m-2 amongst the lines. However, the large-ear phenotype (long rachis, high spikelets ear") was not associated with greater grain yield due to a trade-off between grains m-2 and individual grain weight. The physiological mechanisms potentially explaining this trade off are analyzed. Harvest biomass was positively correlated with grain yield amongst the DH lines. So traits to improve biomass whilst maintaining harvest index may be important for future breeding. Present results showed a positive correlation between pre-anthesis RUE and harvest biomass amongst the subset of 15 lines of the NL2 x Rialto DH population. It is suggested that breeders might select for higher RUE (via high specific leaf weight) to improve grains m-2 and yield potential in future years.

Large numbers of adventitious shoots have been induced to form in vitro on floral stem sections of Tulipa gesneriana L. cultivar Merry Widow. In comparison with explants of scale and axillary bud, floral stem tissues showed the greatest potential for shoot production. A modified Murashige & Skoog medium contained inorganic salts and vitamins at full strength and supplemented with benzylamino-purine and napthalene-acetic acid at 1 mg‾1 induced shoots on 70%-90% of floral stem explants. The stage of development of the bulb was found to be an important factor in determining the ability of explants to regenerate shoots. The shoot producing potential of floral stem tissues was greatest during the 'dormant' phase of the bulbs, but the ability to produce shoots was lost once rapid extension growth and greening of the floral stem had commenced. Morphogenesis in vitro was found to be influenced by the origin of explants from within the floral stem. A study of endogenous plant growth regulators was made within the floral stem in order to elucidate their role in the organogenetic processes occurring in vitro. A study of histological and morphological development in vitro showed that the shoot-like structures arise from the epidermal cell layer and have the potential to form whole plants.

Pyrethroid insecticides act on the voltage-gated sodium channel and mutations of the channel can confer resistance in many insect species. For example, the kdr (LI014F) mutation found in domain IIS6 and the super-kdr (M918T) mutation found in the IIS4-S5 linker of the insect Drosophila melanogaster para sodium channel reduces the sensitivity of the channel to pyrethroids. Two mutations found in different pyrethroid-resistant strains of Bemisia tabaci were incorporated individually into the para wild type sodium channel of Drosophila and expressed in Xenopus laevis oocytes to investigate their effect on pyrethroid sensitivity. Voltage clamp assays showed that the M918V mutation conferred a 16-fold and a 800-fold reduction in para sensitivity to deltamethrin and permethrin respectively. The T929V mutation, caused a 2600-fold reduction in para channel sensitivity to deltamethrin. A T929M mutation, which at the equivalent residue position in the human skeletal muscle sodium channel causes Hyperkalemic Periodic Paralysis in humans, gave similar deltarnethrin insensitivity. All three mutations reduced the sensitivity of para channel populations by reducing the number of channels in the open state, to which deltamethrin and permethrin bind preferentially, and by reducing the affinity of the pyrethroid for the channel. The rat IIA voltage-gated sodium channel, which is approximately 4500-fold less sensitive to pyrethroids than the insect para sodium channel, has an isoleucine at the equivalent super-kdr residue. Replacement of this with either methionine or cysteine, increased the sensitivity of the channel to deltamethrin >80-fold and to pennethrin by 150-fold. These mutations highlight possible locations of pyrethroid binding sites and give insights into the mechanisms by which pyrethroids modify sodium channel behaviour. Kdr and super-kdr mutations are found in the housefly and a DNA diagnostic was used to show that the genotypes present in field populations reflected the selection pressure imposed by different insecticide regimes.

Effects of various pollen types on the fruit growth and development in two maternal cultivars of Omani Date Palm were studied in the Northern Batinah region of the Sultanate Oman. Discrete stages in the development were identified, quantified and examined with regard to important variables including fruit set, weight, size, maturity, chemical composition, appearance and yield. Procedures were developed to compare across the different maternal cultivars and temperature environments. The pollen types were distinct in their effects, particularly as regards weight, time to maturity, ripening, sugar content, appearance and yield of certain consumable fruit stages. These effects were influenced by the female type and differential fruit set. True metaxenic and xenic effects were evidenced by excluding influences of fruit set. These were on fruit fresh weight, size, maturity and ripening in cv Khasab in 1996 and 1995 and in cv Khalas in 1996. Differences in cv Khalas in 1995 were due to differences in fruit set. Pollen effects could be measured in cv Khalas throughout fruit development, while they appeared in cv Khasab only in the later stages. Khori consistently induced the highest mature fruit fresh weight (14.8 g in cv Khalas, 13.0 g in cv Khasab) compared to Bahlani (12.6 g and 12.3 g, respectively) and AI Arudsabba (12.2 9 and 11.1 g, respectively). However, differences in fruit set between pollen blocks in cv Khalas in 1995 caused the largest ripe fruit fresh weight (16.1 g) in the AI Arudsabba block compared to Bahlani (14.1 g) and Khori (13.4 g). The effect of high fruit set (initial set was 49 % with Khori and 34 % with AI Arudsabba) in masking and modifying pollen effects was evident because AI Arudsabba induced about 40 % less fruit fresh weight than Khori in the initial stages of development. The response to applications of plant growth regulators was specific to the pollen type used. GA increased, by about 100 %, fruit fresh weight in AI Arudsabba pollinated Khalas fruits but reduced it to about 50 % in Khon pollinated ones. NAA caused the abscission of all unfertilized ovaries in Khon pollinated Khalas but not in those pollinated with AI Arudsabba. In the absence of syngamy physiological rather than hereditary causes were implied. Correlations between fruit set and fruit fresh weight did not exist in the early stages suggesting that the observed pollen effects were truly metaxenic or xenic. In the later stages clear and consistent negative correlations existed for the AI Arudsabba block. Probably in the other pollen blocks some mechanism compensated this control of one variable over the other. Late correlations for the Khori block in cv Khalas suggested that high fruit fresh weight induced fruit drop. The absence of pollen effects on late correlations in cv Khasab implied a genetic cause. The strong influence of fruit set on ripening (% ripe fruits) in Khori pOllinated bunches indicated a specifically strong influence exerted by fruit set over ripening. Time to physiological maturity was affected by pollen type only in cv Khalas where AI Arudsabba and Bahlani induced earlier maturity (7 days) than Khori. Khori pollinated fruits appeared to mature later in both female cvs except cv Khalas in 1995. Bahlani induced earlier maturity in both female cvs. Regression analysis between thermal time and fruit fresh weight provided evidence for the effects specific to Khori. As Bahlani induced the same early maturity in both female cvs. Ripening was most uniform in Bahlani pollinated bunches, but faster in Khori pollinated ones. Correlations of thermal time and ripeness indicated that the temperature regime has a strong influence (r=0.99) over ripening in Bahlani pollinated bunches. Early pollen effects were probably due to physiological mechanisms, probably hormonal activity, which could be attributed to pollen type and pollination. Late effects were under the influence of male x female interactions and were thought to be genetic. Bahlani consistently induced the highest fruit fresh weight and size in the early fruit stages, but Khori in the later stages. Only in cv Khasab was Bahlani in the later stages on par with Khori in this regard. The situation was similar for fruit and seed size. Compositional differences between pollen types were not reflected in those between the ovaries one day after pollination with different male types. This largely precluded the possibility that the early growth response was directly due to the mere addition of substances contributed by the pollen grains. Preliminary investigations indicated that pollen types were a priori distinct with regard to their biochemical composition and mineral content in that AI Arudsabba and Bahlani were similar and differed from Khori. Khori's pollen grains were largest (22 mum, less than 20 mum in other types) and its pollen tube growth the most uniform (CV 56% compared to 80-110% with other types), while Bahlani had the most vigorous pollen tube growth (tube length up to 220 JlI1lI24h). Khori contained more growth promoters, possibly GA , than AI Arudsabba. Khori brought about relatively stable bunch yields in cv Khalas (11 kg in 1996, 15 kg in 1995) and large (about 4 cm long), heavy and sweet fruits, but delayed maturity of the fruits (7days in cv Khalas). AI Arudsabba produced a slightly higher cumulative yield (28 kg) of similar yield stability, but produced fruits of poor quality in regard to fruit size (about 3.5 cm in cv Khalas), fresh weight and a low total sugar content (less than 40% in Khalas, less than 50 % in Khasab). Bahlani had clear advantages, in that it induced sweet fruits, but produced the least stable yields of fruits (cv Khalas: 16 kg in 1996, 7 kg in 1995) with relatively low weight and small fruits.

Experiments were conducted in growth rooms to study the photoperiodic response of Pentland Crown. In field experiments the effects of sprouting techniques and the possibility of mixing of different physiologically aged tubers and the use of plant growth regulator, pp333 were studied. Sprout growth of the tubers used for planting was studied during storage. Light interception in the photo-synthetically active range (PAR), was measured in the crop canopies. Relevant literature relating to the present investigation was briefly reviewed. Tuberization in Pentland Crown was stimulated by relatively short days, lower temperature and higher irradiance. Pp333 allowed closer plant spacing (61 x 20cm) without any visible crowding effect, further it increased the allocation of assimilated to the tubers, which resulted in higher tuber yields and with a higher proportion of medium sized tubers. Sprout growth was linearly related to the initial tuber weight and day degrees above 4oC from dormancy break. Storing tubers in the cold before planting increased the sprout number and thus the proportion of main stems in the field. Time to reach 50% emergence was not reduced with increases in physiological age over 80 day degrees above 4oC. Cold (tubers stored at 3+/- 1oC until a day before planting) delayed tuber initiation but once the tuber had been initiated then the effect of physiological age disappeared and further tuber or overall plant growth or development was no more affected by the physiological age of the seed tuber. Yields from mixing different physiologically aged tubers were not different from those expected. The major factor affecting the growth of the crop was the water supply. The overall photosynthetic conversion efficiency of the canopy (g dry weight MJ-1 was intercepted) was 3.42g in 1980 in absence of any apparent water stress while in 1979 it was only 2.24g due to winter stress.

A series of field and growth room experiments on winter barley (Hordeum vulgare) L. syn. H. sativum Jessen) were undertaken between 1980 and 1983 at the University of Nottingham School of Agriculture, Sutton Bonington. The aim of this study was to attempt to elucidate those factors which influence the suitability of harvested grain for use as seed. Density, nitrogen fertilizer (both rate and timing) and plant growth regulator applications were used to modify crop growth and development with a view to enhancing the suitability of the grain for seed purposes. It has been shown that the final grain yield and yield components could be manipulated by the judicious use of the inputs examined. However yield component modification was dependent upon the variety used. Consistent increases in seed yield as a result of the husbandry inputs were not always detectable but where alterations to crop growth and development did occur this occasionally resulted in a reduction in total grain yield. None of the PGRs applied significantly or consistently influenced the suitability of the grain for seed purposes. All nitrogen trials were conducted on Index 0 nitrogen sites. However the residual nitrogen may have differed between sites and seasons so confounding the effects of nitrogen treatments. Alterations of both nitrogen rate and timing can be used to modify crop growth patterns. Alteration of sowing density resulted in a change in the grain yield components. Increased sowing density resulted in an increase in total ear number with a concomitant reduction in mean grain number per year. As grain yield was shown to be correlated with grain number per unit area the modification of these two components by sowing density did not necessarily influence final grain yield because of yield component compensation. The seed industry is still divided in its attitude to the desirability or necessity of size graded seeds. However if more emphasis is placed on the production of cereal seed crops the work reported here will help to clarify the possible outcome of desirable modifications to the growth and development of the winter barley crop for seed.

Winter wheat (Triticum aestivum L. ) is the most important crop grown extensively in the UK. There is a gap between yield production and world demand for wheat. So, there is a need to fill this gap. The overall objective of the present study is to investigate the physiological determinants of grain yield potential in winter wheat grown in UK conditions using doubled-haploid lines derived from a cross between winter wheat varieties Rialto and Spark. These varieties are known from previous work to contrast for source and sink type traits and for the presence/absence of the 1 BL/ IRS translocation and the Rht-Dl b semi-dwarf allele. Three field experiments (at Sutton Bonington, University of Nottingham 2003/4, 2004/5 and 2005/6) were conducted examining 25 DH lines of the Rialto x Spark population and the two parents. Two post-anthesis shading treatments (with and without shading) were applied to six genotypes (four DII lines and two parents) in 2003/4 and 2004/5. Two post anthesis de-graining treatments (with and without degraining) were applied to twelve genotypes (ten DH lines and two parents) in 2003/4 and 2004/5. Detailed measurements of grain growth were carried out on the two parents for five pre-determined grain positions within the ear. A range of physiological traits were measured, including developmental stages, light extinction coefficient, radiation interception, radiation-use efficiency (RUE), green area and biomass, stem water-soluble carbohydrate reserves, floret fertility, potential grain weight, grain filling rate and duration, final grain weight and combine grain yield. A source-sink balance model which quantified the source: sink balance during grain growth indicated that the four DH lines and the two parents were sink-limited during grain growth. The sink manipulation treatment (de-graining) generally confirmed the sink limitation in this population although small positive responses of grain growth to de-graining for a few lines indicated they may have been close to source limitation. Radiation-use efficiency measured as the regression slope of dry matter on accumulated PAR intercepted between onset of stem elongation and anthesis differed amongst genotypes in 2004,2005 and 2006. Pre-anthesis RUE was positively correlated with each of grains m2 and specific leaf weight (SLW). The 1BL/IRS translocation increased RUE significantly. The characterisation of the 25 DH lines in this study showed that the differences in grain yield were positively correlated with grains m'2 but not individual grain weight. There was positive correlation between stem WSC reserves and yield in one of the experimental seasons, 2006. The ten DH lines and the two parents differed in the length of the period between GS31 and GS61 by nine days. There was a positive correlation between the duration from GS31 to GS61 and radiation interception during this period which positively affecting grains m '2 Rate and duration of grain growth and final grain weight were assessed for five grain positions (G1 to G5) for Rialto and Spark under 50% shading and a control treatment. Rialto had heavier grains associated with a longer grain filling duration than Spark. The five grain positions had similar durations of grain filling but differed in final grain weight and rate of grain growth. Grains in the central spikelet (G1, G2 and G3) were sink-limited as they did not respond to de-graining. However, grains in the basal (G4) and apical (G5) spikelets were marginally source-limited since their final weight was increased by de-graining. These results suggest that breeders should consider selecting for extra grains in proximal grain positions in basal spikelets (e. g. G4) rather than in distal grain positions in central spikelets, because these grains in this position were heavier, had faster filling rate and had the ability to respond to extra assimilates later in the season. Harvest biomass was positively correlated with grain yield amongst the DH lines. So traits to improve biomass whilst maintaining harvest index may be important for future breeding progress. It is suggested that breeders might select for an extended duration between GS31 and GS61 and higher RUE (via high SLW) to improve grains M-2 and yield potential in future years. They also should select for higher stem carbohydrate reserves to increase source size alongside grain sink size.

The four lettuce (Lactuca saliva) cvs. Evola, King Louie, Pic and Robusto were transformed with the binary expression construct pAFQ70.1, using Agrobacterium tumefaciens strain AGL 1. The construct carried the glutathione metabolic genes gshi, gshlI, phgpx and gorI. Both the gshI and gshII genes were fused to sequences encoding the pea glutathione reductase transit peptide (grIp), and were intended to influence glutathione synthesis and metabolism in the chloroplasts. Reverse transcriptase PCR analysis of cvs. King Louie, Pic and Robusto T0 transformants revealed that expression of the transgenes followed a varied pattern. These variations were most likely due to post-transcriptional gene silencing created by the presence of strong promoters, homology with endogenous plant genes and presence of multiple genes in a single vector. The presence of the transgenes, gshI, gshII, phgpx, and gorI, in cv. King Louie T3 homozygous lines was confirmed by genomic DNA dot blots and Southern blots. It was hypothesized that transformants would have an increased glutathione pool in the chloroplasts and thus would be able to withstand the damaging effects of active oxygen species generated by environmental stresses. Leaves of transgenic homozygous T3 cv. King Louie lines were shown to have a 2-fold greater glutathione concentration than their respective azygous counterparts, although total antioxidant activity was similar in all lines. However, this did not result in enhanced stress tolerance, with the homozygous lines exhibiting no physiological or morphological advantage compared to the azygous and wild-type lines when grown under saline stress (150 mM NaCl). Glasshouse trials during the summer of 2005 determined the susceptibility of cv. King Louie T3 homozygous, azygous and wild-type lines to the foliar, stress related disorder tipburn. Wild-type plants grown both under calcium deficient conditions at the University of Nottingham and in a trial at Elsoms Seeds Ltd., Spalding, UK, had a reduced incidence of tipburn compared to transgenic plants of the homozygous and azygous lines. Macroscopic of tipburnt leaves revealed the condition formed sporadically, with small dark sunken necrotic spots spreading along the leaf margin restricting leaf expansion. Microscopic transverse sections of tipburnt leaves showed total collapse, disintegration and necrosis of the leaf structure.

A detailed literature review was done which indicated that there was still some `uncertainty' as to the exact cause of lodging and also identified the need for a quantitative method to assess lodging risk. Separate published models for determining the windthrow of trees and the anchorage of wheat roots were combined, and a model was developed in order to integrate all aspects of lodging in wheat, and express them in terms of risk. The model was broadly sectioned into three components; the plant canopy, stem base, and roots. The aerial force imposed on the stem base and roots was calculated (using both plant measurements and randomly selected weather conditions in July). By comparing this to the failure moment of the stem base and roots, the model then predicted the probability of lodging occurring. At the same time, wheat was grown in a series of field experiments at ADAS Rosemaund, Herefordshire between 1994-1996 and the effects of various agronomic factors on the crop and its yield were found to be similar to those reported in previous work and from practical experience. Lodging was most prevalent during the 1995-96 season causing yield losses of up to 1.3 t/ha, while very little lodging occurred in the previous two seasons. Reductions in grain quality were also associated with lodging in both the 1994-95 and 1995-96 seasons. Lodging was observed to occur by both stem failure and root failure, with root failure being the predominant cause in 1996. Lodging was influenced most of all by 'crop structure', as affected by agronomy, which was clearly illustrated by 93% lodging occurring in the early-sown, high seed rate, high residual nitrogen treatment compared to only 8% lodging in the late-sown, low seed rate, low residual nitrogen treatment. It was found that the latter treatment described, with the addition of full PGR, had no lodging in any season, as a direct result of lodging resistance gained from optimising plant structure due to crop husbandry. The actual 'type' of lodging was also influenced by the state of the soil; in the dry summer of 1995, soil strength was very high (average c. 100 kPa) and lodging occurred by stem failure, whereas during 1996 when root lodging occurred, the surface soil was moist and soil strength was much lower (average c. 20 kPa). Agronomic practices greatly affected lodging risk in the field experiments. A low seed rate (250 seeds/m2) provided the most consistent and effective method of reducing lodging in all seasons, by significantly increasing the stem diameter (by up to 0.35 mm) and improving root structure (by producing up to 7 more crown roots and increasing the size of the root cone diameter by up to 7 mm). Early sowing (late-September) increased crop height (by up to 6 cm) in all seasons except 1994-95 and resulted in increased lodging in the 1995-96 season. High soil residual nitrogen increased lodging slightly but its effect on `crop structure' was much less than seed rate or sowing date in all seasons. Plant growth regulators (PGR) reduced lodging compared to the nil `control' by significantly reducing stem height (average c. 10cm), but not through increasing stem failure moment or thickening the stem wall width. The reduced nitrogen `canopy management' treatment also generally reduced lodging across seasons compared to the nil `control' although, not by as much as or as consistently as with PGRs. Two PGR-use schemes currently available were examined and recommendations given were found to be poor when compared to the experimental findings and much less `comprehensive' than the modelling approach used here. Other results from a range of winter wheat varieties tested found that variation in basal stem structure and crown root structure was large, which was shown by the model to have implications in terms of lodging risk. These findings indicate the need for improved information and better targeting of varietal lodging resistance in the future. Other findings showed that the use of 'Baytan' seed treatment significantly decreased lodging risk by producing a deeper crown root anchorage and a larger root cone diameter. It was also found that severe stem base disease (fusarium and sharp eyespot) reduced the stem failure moment causing up to 40% greater lodging risk compared to uninfected stems. The model was then used to support the experimental findings by converting the large differences caused in plant structure into estimates of lodging risk and results showed that model probabilities matched reasonably well with the actual lodging in the various experimental treatments. Certain measurements such as plant height and angle of root spread were found to be unimportant. In contrast, a model sensitivity analysis found that plant natural frequency, stem base diameter and root cone diameter were crucial `indicators' of lodging risk. It was also found that wind speed and field altitude were less influential than rainfall in increasing lodging risk. A handheld lodging device (torquemeter) was field tested and provided important results which found the relationship assumed in the model between soil strength and root failure to be flawed, so that root lodging was underestimated. This finding has allowed considerable improvements to be made to the below-ground model. The identification of various `indicators' of lodging risk have successfully provided the basis for further development of the model, to enable a more quantitative, predictive lodging risk assessment scheme for use by farmers and consultants.