Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

End date: 2019Subject: search.filters.subject.300000 Agricultural, Veterinary and Environmental Sciences

Search Results

Now showing 1 - 10 of 197
  • Thumbnail Image
    Item
    Multiple trait improvement of radiata pine : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Forest Genetics and Breeding at Massey University, Palmerston North, New Zealand
    (Massey University, 2000) Apiolaza, Luis Alejandro
    This thesis explores the use of multivariate models in a tree breeding program with emphasis in radiata pine. It considers the development of breeding objectives, the efficiency of various strategies for subsampling trees to assess wood properties, and the analysis and exploitation of longitudinal data. A model for a vertically integrated production system is developed — comprising forest production, pulp mill and sawmill — and evaluated for Chilean production and economic circumstances in each of three silvicultural regimes. The traits in the breeding objectives were volume at harvest age (m3/ha) and average basic wood density (kg/m3). Economic values for each trait were calculated as the difference in discounted profit for a unit marginal increase of volume or density. The objectives for different silvicultural regimes were similar, and a single objective — with relative weights 1:1.47 — appears to provide more economic gain than the use of specialist objectives. Various subsampling schemes for wood property traits in progeny tests were studied through simulation in terms of reliability of estimates of genetic parameters, prediction of breeding values and expected genetic gains. Subsampling is subject to the Law of Diminishing returns, and measuring more than 15 trees per family did not provide large gains in accuracy of genetic parameters or in prediction of expected gain. A unified view of multivariate analysis with longitudinal data from progeny trials is presented using a tree model. Several statistical models to deal with covariance structures are specified, the relationship between full multivariate analysis and random regression models is demonstrated, and model selection techniques are presented. Different models are compared for repeated assessments of basic wood density (kg/m3). These models are further developed including additional random effects (block and plot) with an application to height (m) data using a Chilean radiata pine progeny test. Covariance structures reduce the risk of non-positive definite additive genetic matrices, while reducing computational demands for the analyses and providing a description of the genetic control of a trait over time. Longitudinal data were used to predict breeding values close to rotation age, using either mass or combined selection. The method was tested under three covariance models and two breeding delays (time between selection and propagation of sufficient offspring for planting), to determine the best age or combination of ages for selection purposes. A combination of family information and repeated assessments provided the highest genetic gains.
  • Thumbnail Image
    Item
    Mechanisms of copper uptake and transport in plants : a thesis presented in partial fulfilment of the requirements of the degree of Doctor of Philosophy in Soil Science at Massey University, New Zealand
    (Massey University, 2000) Liao, Mingtan
    The Cu concentration in plants varies considerably between species. This suggests different abilities to either absorb Cu from soils or translocate Cu from root to shoot. The main objective of the thesis was to provide a fuller understanding of the mechanisms of Cu uptake and transport in plants which may lead to the development the strategies to improve Cu uptake by pasture crops. Glasshouse experiments with the Cu hyperaccumulator Haumaniastrum katangense showed that Cu hyperaccumulation in shoots was not found. It was concluded that H. katangense plants tested in these experiments were Cu tolerant rather than having hyperaccumulator status. The mechanism of high tolerance to Cu could be due to the restriction of Cu transport from roots to shoots. Nutrient solution culture experiments with the Ni hyperaccumulator plants Alyssum bertolonii and Berkheya coddii showed that co-hyperaccumulation of Cu and Ni did not exist. Alyssum bertolonii was not a Cu-tolerant plant, whereas B. coddii exhibited a much greater degree of tolerance to this metal, and the tolerance of B. coddii to Cu was not at the expense of Ni uptake. It was concluded that B. coddii should be considered as a possible plant for phytoremediation of soils contaminated with both Cu and Ni and it is recommended that field trials be carried out to establish this potential. NFT nutrient solution culture experiments showed that a large proportion of total Cu uptake by chicory and tomato plants was retained by roots except when plants were grown in the basal nutrient solution (0.05 mg Cu L-1). Copper retention by roots, limited Cu translocation to xylem and shoots. Large differences between measured and predicted Cu accumulation by shoots of tomato and chicory suggested that some xylem-transported Cu is recirculated to roots via the phloem. A Cu speciation study showed that more than 99.7% of total Cu in tomato and chicory xylem sap was in a bound form. Increased Cu concentrations in the rooting media induced selective synthesis of certain amino acids which include NA, His, Asn and Gln, all of which have high stability constants with Cu. Nicotianamine and His have the highest binding constants for Cu and the concentrations of NA and His in chicory and tomato xylem saps can account for all the bound Cu carried in the sap. Copper recirculation within plants was demonstrated by an experiment with hydroponically grown tomato plants in a split-root system. Significant amounts of Cu were translocated from roots bathed in a solution of high Cu concentration to another half root system exposed to low Cu. Shoot Cu concentrations were positively correlated to plant water use (mL g-1 DM). A Cu recirculation model was suggested. Efforts have been made to develop the strategies to improve Cu uptake by pastures. The initial uptake of Cu from CuSO4-fertilised soil can be increased by 10-21 % by addition of His and casein. Casein was generally more effective at increasing plant Cu uptake than His and other amino acids. The Cu(OH)2-based fertiliser was less effective than the CuSO4-based fertilisers in supplying Cu to ryegrass grown in pots of Ashhurst stony silt loam and Wairoa pumice soil. In general, among the three CuSO4 fertilisers, Ca-caseinate-CuSO4 resulted in higher Cu uptake by ryegrass grown in both soils. The factors constraining Cu uptake by ryegrass plants from Cu-fertilised soils were elucidated. Linear relationships between ryegrass Cu uptake and total soil solution Cu concentration were soil type dependent, despite each soil having similar soil solution Cu concentrations. Between 98.5-99.5% of the soil solution Cu was in complexed forms. No relationship between the Cu2+concentration in soil solution (expressed as pCu2+) and Cu concentration in plants was found. Free Cu2+ concentrations in soil solution were sensitive to pH change. The extent of the increase in free Cu2+ concentration per unit decrease in pH was dependent on soil type. It is suggested that the rate of Cu uptake by plants is likely to be dependent on both the concentration of organically complexed Cu in the soil solution and the stability of this complex to pH change.
  • Thumbnail Image
    Item
    Distribution of Neotyphodium lolii-endophyte metabolic activity in perennial ryegrass (Lolium perenne, L.) and its implications for alkaloid distribution and photosynthesis : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Microbiology at Massey University, Palmerston North, New Zealand
    (Massey University, 2000) Spiering, Martin Jürgen
    Neotyphodium lolii is a fungal endophyte of perennial ryegrass {Lolium perenne). In this symbiosis, alkaloids are produced that significantly impact on the performance of farmed animals. Little was previously known about the physiological conditions for the endophyte in the plant leading to their production. A strain of N. lolii, previously transformed with the β-D-glucuronidase (GUS) gene of E. coli under the control of a constitutive fungal promoter, was used for investigations into the in planta metabolic activity of the endophyte; distribution of the alkaloids ergovaline, peramine, and lolitrem B; and photosynthesis. In vitro studies with this transformed N. lolii strain demonstrated the utility of constitutive GUS expression for assessing the metabolic state of the endophyte. By using constitutive GUS expression and a method for quantitation of the in planta biomass of the endophyte, the endophyte metabolic state (EMS) in the grass plant was determined. The EMS was high and uniform in plant tissues and genotypes differing in endophyte concentration, indicating that proliferation of the endophyte in the plant is not controlled via the EMS. Ergovaline, peramine, and lolitrem B exhibited each a characteristic within-tiller distribution maintained across different plant genotypes. None of the alkaloids was distributed in exact proportion to the distribution of metabolically active endophyte mycelium. Differences in the accumulation of the alkaloids per mycelium were observed between plant tissues and plant genotypes, suggesting differential rates of synthesis and/or degradation of the alkaloids in the mycelium and translocation within the grass tiller. Rates of net photosynthesis at high light intensities were lower in plants infected by N. lolii, indicating for an effect on photosynthetic capacity. However this effect was plant-age dependent. Plant growth was not strongly affected by the endophyte, but infected plants had consistently lower leaf elongation rates. The changes in leaf elongation and photosynthetic capacity in infected plants might signal for an effect of N. lolii on the nitrogen metabolism of its host. The experiments concerning the in planta EMS, alkaloid distribution, plant growth, and photosynthesis were conducted in a controlled environment the establishment of which was part of this study. In addition, for the detailed mapping of ergovaline within the grass tiller a method for quantitative extraction of this alkaloid was developed and optimised.
  • Thumbnail Image
    Item
    Investigations into the influence of fertiliser history and climate regime on the soil fertility, soil quality, and pasture production of Wairarapa hill soils :|ba thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science at Massey University
    (Massey University, 1994) Moir, James Laing
    The effects of long-term application of single superphosphate (SSP) on soil plant-available nutrient supply and indicators of soil biological quality was investigated on Wairarapa hill soils ranging widely in previous fertiliser history (from 0 to 250 kg SSP ha-1 yr-1) and climate regime (annual and seasonal rainfall distribution). At 12 field sites spring pasture response to strategic N fertiliser application was measured, while the plant-available nutrient (P, N and S) supplying capacity of the soils was assessed in glasshouse studies. Based on the pasture growth patterns in field and glasshouse studies, a new climate-driven, soil fertility dependent pasture growth model was developed and tested. In addition, the suitability of the Biolog™ GN microtitre plating system was assessed as an indicator of soil 'quality', using these Wairarapa hill country soils. Results of soil analyses indicated that small increases in mineralisable N, in the order of 280 kg mineralisable Nha-1, with increased rates of fertiliser (P and S) may represent inefficient use of P and S fertiliser. Soil mineralisable N increased by approximately 8.6 kg mineralisable Nha-1 for every 1 unit increase in Olsen P. The ratio of accumulated plant-available N:P:S of these soils, resulting from long-term SSP applications, is approximately 17:2:1. Olsen P status was shown to be strongly correlated with measures of plant-available N and S. Pasture growth response in the field to strategic N fertiliser (30 kgNha-1) applied in spring was highly variable across sites, and within the range of 0:1 to 31:1 kgDM kgN-1. Simple single factors representing soil fertility indices, or climatic regime, could not explain the variation in site-to-site pasture growth response to applied N. Factors constraining N response are discussed. In glasshouse studies, on samples of the same soils, ryegrass and white clover showed large yield differences (clover, 0.27-2.29 gDM pot-1; ryegrass, 0.22-2.25 gDM pot-1) on low P status and high P status soils respectively. Glasshouse DM yields did not correlate with those measured in the field, confirming that at field sites yield responses to nutrient availability are strongly modified by (site-specific) climate. The relationship between Olsen P and clover yield in the glasshouse (curvilinear, R2 = 0.80) was similar to that previously seen in (spring) field conditions. The S:P and N:P ratios of clover in the glasshouse trials confirm that P availability in these soils is the major growth-limiting factor, probably followed by S or N, which becomes limiting when P availability is adequate to high. A modified Stanford and DeMent bioassay technique was used to estimate the amount of plant available N, P and S in each soil. Using an exhaustive cropping regime, these soils exhibited a large variation (range) in ryegrass yields when soils were the sole source of P and N. Yields for each soil were strongly correlated with various soil tests for N, S and P availability. S availability to plants was less variable across soils, but the smaller variation in S limited yield was still strongly correlated with the variation in a newly developed soil hydrogen peroxide-extractable S test. Results from both glasshouse experiments provide strong evidence that the Olsen P soil test is a valuable soil fertility indicator of plant-available P, N and S on legume-based pasture soils with a history of superphosphate use. The amount of dry matter production, when considered with the quantity of soil used for each treatment (-N, 100g; -P, 50g; -S, 25g), suggest that these soils have large pools of plant-available or mineralisable P and S, and, relative to plant demand, small pools of soil mineralisable N. A four-fold increase in field DM production resulted from a 3-fold increase in soil mineralisable N at these sites. This suggests that the rate of N cycling probably also increases with yield increase, and that the size of the soil mineralisable N pool is not directly related to pasture N supply. A new climate-driven, soil fertility dependent pasture production model has been developed and tested using actual DM yields from the field trial sites. The model assumes that pasture growth is proportional to evapotranspiration, and that the proportionality constant (k) depends on soil fertility Pasture growth per mm of evapotranspiration was strongly related to soil available P status at these sites. From results of the glasshouse study, it was concluded that Olsen P was a strong indicator of 'general' (plant-available P, N and S) across these sites, and therefore suitable for use as the soil fertility proportionality constant in the pasture production model. Soil-limited evapotranspiration is calculated from a simple daily soil water balance model. Values for k varied from 11 to 19 kg DM ha-1 mm-1 of evaporation. With the exception of growth after severe drought conditions, the model shows potential to closely predict actual pasture yield. It is hoped that discrepancies between the modelled and measured production may lead to useful speculation and further research on the interacting effects of weather and fertility on pasture growth. The Biolog™ GN microtitre plate system, for comparing substrate use patterns of 95 single C compounds was assessed as an indicator of soil microbial functional diversity across the 12 test hill soils. Preliminary studies showed that saline extracts of different fertility status pasture soils used for Biolog™ microtitre plate assay inoculation contain significant amounts of readily available C. It was concluded that in order to interpret the substrate use patterns correctly, this effect must be corrected for. The Biolog™ microtitre plate system, for use as an indicator of soil quality and health, was shown to have limited application to this range of pasture soils with differing pasture histories. Adaptive factors, such as constitutive and inducible enzyme activities, were shown to complicate the interpretation of microbial growth on the C substrates. Substrate use patterns also changed when soils were rewetted and incubated. Possible 'indicator' substrates were identified, but it was concluded that these were low-energy decomposition products, and as such, are not useful as indicators of microbial functional diversity across these soils. Further research would be required to establish how stable the substrate use patterns are, or the relevance of these indicators to field soil processes. However, as a research tool, the Biolog™ assay showed potential to separate these soils on the basis of microbial functional diversity. The direction of future research, and limitations of current techniques used in this field are discussed.
  • Thumbnail Image
    Item
    Studies on the dynamics of organic sulphur and carbon in pastoral and cropping soils : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science at Massey University
    (Massey University, 2000) Singh, Bhupinder-Pal
    Soil organic matter (SOM) can be depleted or regenerated by altering land management practices. Soil tests capable of reporting the size of dynamic SOM fractions may be useful for indicating the environmental cost of landuse and management practices. Information on the effect of land management practices on soil organic S content and turnover is scarce. This study evaluated the ability of a sequential chemical fractionation procedure to characterise changes in soil S and C organic fractions on a range of pasture and cropping soils with different management histories. The fractionation involved an initial extraction with ion exchange resins followed by dilute (0.1 M NaOH) and concentrated (1 M NaOH) alkali. In addition, recently rhizodeposited 14C (root+exudate derived) produced during a short-term (one week) 14CO2 pulse-labelling study of intact soil cores growing ryegrass/clover pastures, was used to trace the fate of root-derived C in both chemical and density fractionation procedures. In pasture and cropped topsoils, the major amounts of soil S and C were either extracted in 0.1 M NaOH (49-69% S and 38-48% C) or remained in the alkali-insoluble residual fraction (17-38% S and 46-53% C). These two fractions were more sensitive to change caused by different landuse and management practices than the resin and 1 M NaOH fractions. With a large amount of dynamic soil C remaining in the residual fraction it was concluded that increasing strengths of alkali were not capable of sequentially fractionating S and C in SOM into decreasingly labile fractions. The chemical fractionation allocated recent root and root-released 14C amongst all the fractions. Again, most root 14C appeared in the 0.1 M NaOH and residual fractions. Although small in amount, C of higher specific activity (more recently synthesised root C) was preferentially extracted by resin and 1 M NaOH extracts. Density separation was not capable of recovering recent root and root-released 14C in a single fraction. Root-derived 14C was distributed between light (mostly fibrous root debris) (42%) and heavy (organics attached to clay and silt) (45%) fractions. The dispersing reagent soluble fraction recovered <13% of the 14C. An anaerobic incubation and various acids and oxidising agents were tried, in order to recover a greater proportion of root and root-released 14C as a single identity. These were not very successful in either extracting or increasing the alkali solubility of the root C fraction. A 30% H2O2 pretreatment of soil plus roots, or hot 1 M HNO3 treatment of the residual fraction, were more efficient extractants of the root C fraction and should be investigated further to check their ability to better characterise soil organic S and C fractions with a change in management practices. The 14CO2 pulse labelling study of pasture swards showed a greater allocation of recently photo-assimilated 14C to the topsoil layer with a greater proportion of 14C recovered in roots than in the soil. An in situ soil solution sampling technique with mini Rhizon Soil Moisture samplersTM effectively monitored the rapid appearance of a 14CO2 pulse in soil water at various depths. A comparison of the 14CO2 pulse labelling study under light and dark conditions indicated that, in the light lysimeters, 14CO2 photo-assimilation/translocation/rhizosphere respiration was the main pathway for CO2 generation at various soil depths. In the dark lysimeters, 14CO2 diffusion was the main mechanism and 14C assimilation (either photo-assimilation or assimilation by chemolithotrophs in rhizosphere soil) was small. The 14CO2 activity in soil water from four soil depths of dark and light soil cores, and a CO2 diffusion model, were used to identify the 14CO2 contribution from rhizosphere respiration in the light lysimeters. A model was developed, but the unknown geometry of the air-filled pore space in the undisturbed soil cores made it impossible to precisely calculate the contribution made by root respiration to soil water 14CO2 activity.
  • Thumbnail Image
    Item
    Developing sustainable soil fertility in southern Shan State of Myanmar : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2001) Tin Maung Aye
    Literature review and a farm survey results indicated that the productive capacity of the Red Earths and Yellow Earths (Acrisols in FAO/UNESCO system) in Southern Shan State, Myanmar, continues to decline as poor, near-subsistence, farmers usually fallow-crop these soils and are unable, for economic reasons, to provide the necessary fertilisers and crop management strategies that could improve and maintain soil fertility. This thesis reports on investigations undertaken to determine ways in which the fertility of these soils can be improved in an economical and sustainable manner. A preliminary soil survey confirmed that soils of the Southern Shan State study area had low soil P status, low pH, low SOM (low reserves of N, P and S) and low base saturation, which are likely constraints to crop production on these marginal soils. A farmers' survey indicated farmers were aware of the P availability and soil acidity problems, however, they use low levels of N, P, K fertilisers, green manure and liming material because their economic margins were insufficient to buy expensive P fertilisers and liming materials. Preliminary glasshouse trials were conducted to establish the key soil fertility constraints. These trials included testing the P responsiveness of crops (pigeon pea (Cajanus cajan), rice bean (Vigna umbellata) and upland rice (Oryza sativa L)), the influence of liming materials on legume growth (black gram (Vigna mungo), cowpea (vigna unguriculata), kidney bean (Phaseolus vulgaris), lentil bean (Culinaris lentil), pigeon pea, soybean (Glycine max), stylosanthes (Stylosanthes quyanensis)), and the effectiveness of green manures for building SOM and P reserves in the Red Earths and Yellow Earths. The glasshouse trials confirmed that low P status is the factor most limiting to crops particularly legumes grown in the Yellow Earths. Upland rice, however, did not respond to added P suggesting that upland rice may not be a suitable test plant for evaluating the relative P effectiveness of fertilisers in the Red Earths and Yellow Earths. This pot experiment with the upland rice trial also demonstrated that indigenous Myanmar phosphate rock (MPR) and Farmyard manure (FYM) were ineffective P sources for raising soil plant-available P in the short-term. Local dolomite, however, was an effective liming material and when added with P enhanced the nodule formation of pigeon pea. Laboratory incubation studies showed that incorporating organic amendments (FYM, pigeon pea and upland rice residues) into the Red Earths and Yellow Earths significantly increased soil organic C, improved soil pH buffering, increased the total P content and increased labile-P fractions that could be used for plant growth. The Walkley and Black organic C determination can be used as a suitable 'low tech', portable method for the determination of organic C to monitor soil organic matter levels. Based on the results from the preliminary glasshouse trials, field trials were designed to establish relationships between P fertiliser form, application rate and soil P test levels for maize (Zea mays) and legumes (rice bean and black gram) grown in a Yellow Earth. In soils with initial Olsen-P values of approximately 8 kg P kg-1 soil, two maize field trials consistently indicated that near maximum yield (90%) of maize can be obtained by application of water-soluble P fertiliser (Triple superphosphate, TSP) at 40 to 50 kg P ha-1 in year one and reapplication of TSP at 25 kg P ha-1 in year two. Phosphate supplied as FYM, Tithonia diversifolia, Chinese partially acidulated phosphate rock (CPAPR) and Sechura reactive phosphate rock (SPR) were agronomically less effective as short-term P sources for maize than TSP, with TSP substitution ratio of 0.1, 0.17, 0.61 and 0.07 respectively at an application of 40 kg P ha-1 rate. A legume-wheat rotation field trial showed that rice bean (the legume) yield was significantly increased by the application of TSP at 40 kg P ha-1 plus local dolomite. Subsequently, rice bean plots fertilised with 40 kg P ha-1 as TSP produced the largest wheat grain yields in the Yellow Earth. In all trials the Olsen-P test was a suitable soil P test for providing an index of plant-available P. Olsen-P values at which optimum crop growth occurred (90% maximum yield) ranged between 30 to 40 mg P kg-1 in the Red Earths and Yellow Earths, depending on the season, plant age when harvested and crop grown. Use of the sulphuric acid acidulated CPAPR and elemental S (S°) with SPR confirmed that plant growth in the Yellow Earths was very responsive to sulphur application. Chinese PAPR can be used as a cost-effective P and S fertiliser to increase the crop yield in these Red Earths and Yellow Earths, particularly where S is also deficient. Use of local dolomite (2.5 t ha-1) in the field trials caused significant increases in soil pH in the first season and in the legume-wheat trials resulted in increases in legume yield. The research findings on soil P testing, alternative P sources and liming materials presented in this thesis are discussed in terms of the role they might have in the establishment of sustainable agriculture practice in Southern Shan State, Myanmar. Future research directions that should be taken to realise the productivity of these soils and farming systems are also discussed.
  • Thumbnail Image
    Item
    Magnesium fertiliser effects on forest soils under Pinus radiata : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2000) Mitchell, Andrew David
    Magnesium deficiency is of concern in a number of forest regions in New Zealand and has been linked in recent years to a condition in Pinus radiata called upper mid crown yellowing (UMCY). Magnesium deficiency is also acknowledged as a common nutrient disorder linked to 'new type forest decline' in Europe and the USA. With increases in the number of rotations and increased growth rates through tree breeding, the incidence of Mg deficiency and UMCY is expected to increase. This study investigated the Mg fertility of a range of forest soils, their responses to the application of Mg fertilisers and Mg uptake by P. radiata. New Zealand Forest Research (Institute Ltd) has established a series of Mg fertiliser trials (FR190 series) in a range of forest soils. Five of these trial sites, located in the North Island of New Zealand, where calcined magnesite (calmag) was applied at 150 kg Mg ha-1, were sampled to investigate the effectiveness of calmag in increasing plant available Mg and to determine the fate of the fertiliser. At all of the sites, within two and three years following calmag application, both soil exchangeable Mg and solution Mg concentrations were increased in the top 5 cm. However, the increases were significant only at three of the sites, where the initial soil exchangeable Mg was low. The other two soils had medium to high concentrations of soil exchangeable Mg prior to Mg fertiliser application. Between 70-90% of the applied fertiliser Mg had dissolved and estimated losses due to leaching ranged from 0-20%. Foliar concentrations of Mg were generally improved in the fertilised trees, but the increases were not significant. Symptoms of Mg deficiency and UMCY are worse in trees that have high foliar K:Mg ratios. High foliar K:Mg ratios reflect changes in the pools of soil exchangeable Mg and K. Therefore, the effects of Mg fertiliser application on soil K:Mg molar ratios at the FR190 series trials were examined. In the trials where Mg fertiliser application significantly increased soil exchangeable Mg the soil K:Mg molar ratio was significantly reduced. This could see a reversal of the trend of the soil K:Mg ratios increasing with time and a reduction in the severity of Mg and UMCY symptoms. In the trials that had medium to high concentrations of Mg, the K:Mg molar ratio was not affected by increases in exchangeable Mg from Mg fertiliser application. As there are several Mg fertilisers with varied solubilities available to foresters a study was conducted to determine the rates of dissolution of a range of Mg fertilisers applied at 200 kg Mg ha-1 to a pumice soil under P. radiata in Kaingaroa Forest near Rotorua. Twenty seven months after fertiliser application the mean percentage of Mg dissolved were 100% for Epsom salts, 92% for calcined magnesite 1-2 mm, 91% for Granmag 20 (granulated product from 20% acidulation of calcined magnesite, 2-4 mm), 83% for calcined magnesite 2-4 mm and 70% for forestry grade dolomite. The specific dissolution rate constants (µg fertiliser cm-2 day-1) for the slowly soluble Mg fertilisers were 279 for calcined magnesite 1-2 mm, 220 for calcined magnesite 2-4 mm, 212 for Granmag 20 and 13 for forestry grade dolomite. A computer program based on an elemental sulfur (Sº) oxidation model, where the rate of Sº oxidation depends on surface area of the particles, explained the rate of dissolution of Mg fertilisers within a narrow fertiliser particle size range. Application of Mg fertiliser has been shown to increase plant-available Mg. However, there has been no significant increase in foliar Mg concentrations in the fertilised trees. It was thought that though the bulk soil had sufficient plant-available Mg, some factors in the rhizosphere might be inhibiting Mg uptake by P. radiata. Therefore, trials were conducted to increase the understanding of Mg availability in the soil immediately surrounding the tree roots. Two glasshouse experiments were conducted investigating the tree-induced changes in Mg availability in the rhizosphere of P. radiata seedlings. The first used pumice topsoil fertilised with various forms of Mg fertilisers. The second used pumice sub-soil that had lower exchangeable Mg concentrations and pH buffering capacity. The subsoil was fertilised with different rates of Mg and K fertilisers. There was a significant accumulation of exchangeable Mg in the soil layers near the rhizosplane, compared to the bulk soil for the Epsom salts and granmag fertiliser treatments in the first experiment. A similar accumulation occurred for treatments where Mg fertiliser was applied in the second experiment. Magnesium accumulation at the root surface is probably due to a higher rate of Mg movement by mass-flow compared to Mg uptake by the seedlings. The higher rate of Mg movement was probably caused by high seedling transpiration rates. Magnesium accumulation in the rhizosphere could have also been influenced by ectomycorrhizal fungi growth. Soil pH in the rhizosphere soil of the first experiment was generally unaffected by nutrient uptake of the seedling compared to the bulk soil, probably due to the high buffering capacity of this soil. Whereas, in the second experiment the soil pH, because of the low pH buffering capacity of the soil, was significantly reduced in the rhizosphere compared to the bulk in all treatments. Cation-anion balance without considering N uptake, showed that the seedlings took up an excess of cations compared to anions. Because the ionic form of N taken up by the seedlings was not determined, it was not possible to explain the rhizosphere acidification from the cation-anion balance in the seedlings. Magnesium concentrations in the fertilised seedling in the first experiment increased for all fertiliser types used, but only the increases in root Mg concentrations were significant. In the second experiment Mg fertiliser application significantly increased Mg concentrations in both the shoots and roots. Recently, Forest Research installed a fertiliser trial that manipulated the soil K:Mg ratio through the application of Mg and K fertiliser. This trial was used to study the losses of Mg due to leaching under P. radiata after the application of Mg and K fertiliser. Suction cup lysimeters were installed at 2 depths (10 cm and 45 cm) to monitor changes in soil solution Mg concentrations in the top-soil where the active roots are and the leaching losses of Mg down below 45 cm over an 18 month period after fertiliser application. Magnesium and K fertiliser application resulted in significant increases in soil solution Mg and K concentrations in the 0-10 cm soil layer soon after fertiliser application. However, by 90 to 180 days after application concentrations have returned to levels not significantly different from those of the control treatment. The soil solution K:Mg molar ratio in the 0-10 cm soil layer was significantly increased by both K fertiliser treatments at all sampling times. Magnesium fertiliser application generally decreased the soil solution K:Mg molar ratio, although none of the decreases were significant. Magnesium fertiliser application significantly decreased the soil exchangeable K:Mg molar ratio and K fertiliser application significantly increased the soil exchangeable K:Mg molar ratio. Between 180 to 240 days following application, concentrations of Mg and K in the sub soil lysimeters peaked. Concentrations of solution Mg in the sub soil lysimeters of the fertilised and unfertilised plots were generally greater than solution K concentrations. Estimated leaching losses of Mg were 39.4 kg Mg ha-1 in the Mg fertilised plots and 11.2 to 26.9 kg Mg ha-1 in the K fertilised plots. Estimated leaching losses of K were 8.9 kg K ha-1 for the 200 kg K ha-1 treated plots and 17.4 kg K ha-1 for the 400 kg K ha-1 treated plots. Magnesium fertiliser application did not cause any increase in the leaching losses of K. This thesis has increased the knowledge base of the Mg fertility of a range of forest soils and their response to application of Mg fertiliser. More research is required to determine the reasons for the slow tree response to increases in soil Mg from Mg fertiliser application and the role of ectomycorrhizal in the Mg uptake by P. radiata.
  • Thumbnail Image
    Item
    Kereru (Hemiphaga novaeseelandiae) : impact injuries, morphometrics, moult and plumage : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology at Massey University, Palmerston North, New Zealand
    (Massey University, 2010) Cousins, Rachael Anne
    The New Zealand Woodpigeon or Kereru (Hemiphaga novaeseelandiae) is a monomorphic pigeon that is often seen in urban and rural areas, feeding on native or introduced plants throughout the year. The Department of Conservation (DoC) offices around New Zealand, in particular the lower North Island, receive many Kereru each year due to predation and fatalities caused by impacts with windows and vehicles. Little scientific work has been conducted on such a valuable resource to date, so in this study I accessed and used 50 of these Kereru, as well as 76 reports from the Massey Wildlife Clinic (the wildlife surgery and rehabilitation wing of the Institute of Animal, Veterinary and Biomedical Sciences (IVABS)), 20 specimens from Massey‟s necropsy database and 119 moult records from other workers, to study four aspects of impact injuries and Kereru biology as outlined below. (1) The type and extent of injuries that were sustained through collision events and how this affected rehabilitation. We used radiographs and necropsies to determine the skeletal and soft tissue injuries in 70 Kereru that died in such collisions, and radiographs of 61 birds that were assessed or treated having survived initial impacts. Vehicle collisions tended to result in damage to the extremities (wing and femur), whereas collisions with windows resulted in trauma to the head, fractures/dislocations of the coracoids and clavicles, and ruptured internal organs. Fractured coracoids frequently damaged flight muscles and ruptured the heart. Extensive bruising of pectoral muscles and haemorrhaging of the lungs was due to the force of impact. Rehabilitation time was not related to the number of skeletal injuries sustained, nor was the time until death for those that did not survive. Flight speed and force calculations suggest that a 570g Kereru would collide with 3-70 times the force that smaller birds (5-180g) would; this may explain the discrepancies between the injuries characterised here and those reported for North American passerines. The differences in injuries sustained from collisions with windows and cars can be used to inform rehabilitators about the possible nature of injuries if the source of impact is known. (2) Morphometry, gastrointestinal organ masses and crop contents. Of 50 Kereru that died due to impact collisions, little physical variation was found between sexes; males had longer head/bill lengths. Overall, different structural measures were positively related (mass and tarsus, wing and tail, mass and head-bill and head-bill and tarsus) but variation was generally high between individuals. Fat scores of Kereru were closely related to environmental seasonal variation and 80% of birds were in good body condition. Kereru lack caeca and there were no sexual differences in reference to dry organ mass (liver, intestine, gizzard and crop). Organ masses reflected body mass and size to varying degrees: liver mass was best explained by body mass, gizzard mass by tarsus length as much as body mass, and intestine mass only by body mass. Kereru intestines were proportionately shorter than those of herbivorous grouse, despite grouse having long caeca to help with digestion of plant matter. Kereru seem to rely on long retention times instead, and up to 68g of plant matter were found in the crop, gizzard and intestines. There were no sexual differences in mass of consumed materials found within the gastrointestinal tract, consisting of introduced and native material (foliage/flowers/buds/fruits). Digesta accounted for 0.12 – 13.4% of total Kereru body mass. (3) Kereru flight feather moult, wing area and wing loading. One hundred and sixty nine Kereru moult records showed that Kereru moult over a nine month period (July – March/April), with a restricted moult of tail feathers during the breeding season. Kereru moult is symmetrical in relation to the number of primary feathers moulted, but not in respect to the position on the wing. Kereru often have multiple moult loci and do not follow a conventional moult sequence. This moult strategy reduces the effect that feather gaps have on wing area and thus wing loading. The moult strategy of Kereru is a solution that works to minimise the change in wing area, but at the cost of having a prolonged moult. (4) Plumage colouration assessed using reflectance measurements from light spectrometry. This study is the first to assess UV signals in Kereru and UV signals were found in all eight regions investigated, five plumage (Breast, Crown, Mantle, Wing and Rump) and three bare parts (Bill base, Bill tip and Foot). The greatest intensity of maximum UV signal (uvmax) was in the bare parts with a covariance of the bill tip and foot. No sexual differences or condition dependent signals were found, but age-related UV signals were found in the crown and foot. In the visual spectrum, females had a greater intensity of maximum colour signal (rmax) in the wing. Age-related colouration was seen predominately in the bare parts, in particular the foot which has a higher intensity of colour in juveniles. Even with single-angle light spectrometry Kereru are a highly cryptic species.
  • Thumbnail Image
    Item
    The influence of diet and intake level on hepatic ammonia metabolism and ureagenesis by the ovine liver : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2001) Greaney, Kenneth Barry
    The New Zealand agricultural industry is based on the efficient utilisation of fresh forages, a characteristic of which is a high soluble protein content. A large proportion of the ingested protein is highly soluble in the rumen. A significant proportion of the ingested N is removed from the rumen as ammonia with the bulk of this ammonia being removed from the venous blood by the liver for detoxification to urea. Hepatic urea-N production, or ureagenesis, typically exceeds the rate of hepatic ammonia-N extraction, consequently it has been suggested that the shortfall in N required for ureagenesis is contributed by amino acid-N (Parker et al. 1995; Lobley et al., 1995). This study tested the hypothesis that elevated hepatic ammonia extraction would require a concomitant increase in hepatic amino acid catabolism to supply the additional N required for ureagenesis. In order to evaluate the level of rumen ammonia production and consequently the rates of hepatic ammonia extraction, ureagenesis and amino acid catabolism. the following feeding regimens were tested in sheep held indoors in metabolism crates in three separate experiments; Firstly, lucerne pellets (Medicago sativa) were compared with fresh white clover (Trifolium repens), secondly fresh white clover was offered at either a low or high intake and finally the daily allowance of fresh white clover was fed in two 2 hour periods per day. In each experiment, silicone based catheters were surgically inserted into the posterior aorta and the mesenteric (2), portal and hepatic veins. Following a ten day dietary adjustment period and a ten day nitrogen balance, the sheep were infused with para-aminohippurate (pAH) and 15NH4Cl via the mesenteric vein. The pAH was infused to allow the blood flow across the splanchnic tissues to be estimated, whilst the 15NH4Cl was infused to trace hepatic ammonia metabolism to urea. Blood samples were collected to determine the ammonia, urea, oxygen and amino acid concentrations in the mesenteric, portal and hepatic veins, as well as the posterior aorta. Despite similar DM intakes, the nitrogen intake of the sheep fed fresh white clover was 60% higher (P < 0.001) than that of the same animals fed lucerne pellets. The difference in rumen protein fermentation in these two contrasting diets resulted in higher (P < 0.001) rumen ammonia production in the animals offered fresh white clover. There was, however, only a trend (P = 0.072) toward elevated hepatic ammonia extraction in these animals and urea production was not significantly different to the animals fed lucerne pellets. Hepatic amino catabolism was not elevated in the sheep fed fresh white clover, nor was there a significant difference in the proportion of ME intake that was utilised for ureagenesis between the two groups. In the second experiment the DM intakes of the two groups were different (P < 0 001), with the sheep offered the low intake of fresh white clover consuming 807 g DM/d whilst the high intake group consumed 1118 g DM/d. Even with these differences in intake, portal vein ammonia and urea concentrations were similar. Therefore the rate of hepatic ammonia extraction and urea production were also similar between the two intake groups. However, hepatic extraction of 15N-ammonia was higher (P = 0.033) in the high intake group compared to the low intake group. There was no evidence to suggest that the level of hepatic amino acid catabolism increased with intake level, consequently the proportion of ME intake attributed to urea synthesis was similar for the two intake groups When the experimental animals were restricted to two 2 hour feeding periods per day the DM and N intake decreased by 31% from that of the low intake group in the second experiment. There was no significant effect of time after the onset of feeding on portal ammonia or urea concentrations, hepatic ammonia extraction or hepatic urea production. However portal ammonia concentration and consequently hepatic ammonia extraction and urea production tended to be higher 4-6 hours after ingestion of fresh white clover. However this trend was not observed when the 15N tracer data was used to calculate the hepatic ammonia transfer rate. The ammonia, urea and amino acid hepatic transfer values in this experiment were largely comparable to those recorded for the low and high intake treatments in the second experiment. In these studies, there was no evidence of elevated hepatic amino acid catabolism occurring in response to elevated rates of hepatic ammonia extraction and hence ureagenesis. Additionally there was no suggestion that ammonia provided both of the N atoms of the urea molecule. It is concluded that the liver adapted to the changes in dietary nitrogen supply without incurring significant increases in the metabolic cost of ammonia detoxification to urea. However the nutritional challenges presented to the liver may not have been severe enough to induce measurable changes in hepatic ammonia metabolism. A possible mechanism to account for these observations may be that the liver adapted to the changes in nitrogen supply by altering the activity of the primary regulator of the rate of ureagenesis, carbamoyl phosphate synthetase (CPSI).
  • Thumbnail Image
    Item
    The effectiveness of on-farm control programmes against wildlife-derived bovine tuberculosis in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University
    (Massey University, 2001) Sauter-Louis, Carola
    In New Zealand the Australian brushtail possum (Trichosurus vulpecula), introduced in the middle of the 19th century, is the main wildlife reservoir for Mycobacterium bovis infection for farmed livestock and other wildlife species. Thus, control of tuberculosis (TB) has to involve both livestock and vector animals. Areas with endemic wildlife infection constitute 23% of New Zealand's land area. Vector control is mainly performed by large scale poisoning operations, by both aerial and on-ground baiting, conducted by official agencies, such as Regional Councils. The costs of vector control rose from NZ$18 million in 1995 to NZ$28 million in 1998/99, and finances are not available to cover all areas with endemic wildlife infection. There is a need for farmers to be involved and participate in TB control to complement the official control efforts. This thesis comprises a number of studies that looked in detail at on-farm control measures that could be applied at farm level, their efficiency and cost-effectiveness, in order to determine if and how farmers could take on-farm measures which would complement the official TB control programme. In an initial survey of 27 Wairarapa herd managers, whose cattle herds were TB infected, 'grounded theory' was used to identify factors related to farm management and TB infection in cattle. Most farmers had knowledge or suspicion about potential high risk areas on their farm, where cattle were more likely to become infected with TB. Farms that grazed cattle in paddocks with TB hot-spot areas had a greater herd TB incidence than farms that excluded cattle from such areas, and used adjacent paddocks. Grazing management was found to be flexible, more so on beef farms than on dairy farms. These results formed the basis for designing on-farm control measures. A subsequent intervention study used 67 Wairarapa farms. On-farm control measures were implemented for three years on 34 randomly selected 'focused control' farms. On-farm control measures included targeted vector control in spring and autumn, and adoption of grazing management in summer and winter that excluded cattle from TB hot-spots during these times. These measures were implemented by the research team during the first two years and farmers continued the control work in the third year. At the end of three years the effect of the interventions was evaluated. Focused control farms achieved more effective TB control than standard control farms. They were significantly less likely to have multiple TB animals per year, a higher proportion of focused control farms came off Movement Control, and the two-year cumulative TB incidence was reduced more on focused control farms than on standard control farms. Part of the project was also to compare the Wairarapa project with a contemporary intervention study. The study was conducted on a national scale in four separate areas of New Zealand by a national organisation, using 35 focused control and 70 standard control cattle/deer farms. Farmers were advised by a multi-disciplinary team on possible management changes and vector control for two years. The implementation of these measures was the responsibility of the individual farmers. Three and a half year after the start of the project the effectiveness was evaluated as part of this thesis. Focused control farms reduced the two-year cumulative TB incidence more than standard control farms. Comparison with the Wairarapa project indicated that the hands-on operational approach of the Wairarapa project had advantages over the 'advice only' approach in the national project. All farmers involved in the two intervention studies were surveyed at the end of the intervention studies using a questionnaires, asking about farm management and TB related issues. Only the Wairarapa focused control farmers were interviewed during the project period. Only slight differences existed in these variables between focused and standard control farms in each of the projects, indicating that the allocation of farms to the two farm groups was adequate. Questions were also asked about attitudes towards TB and its control. Overall farmers rated the importance of TB eradication as very high. However, the majority of farmers were not in favour of stricter Movement Control regulations, removal of compensation or having to pay TB testing costs directly. Many farmers saw organisations, such as Government and Regional Council, as being responsible for eradicating TB and did not see any need to conduct control programmes themselves. An economic analysis of the adoption of on-farm control measures was conducted using deterministic, stochastic and decision analysis. Under the current compensation level of 65% for TB test positive animals, the adoption of on-farm control measures generally was beneficial to dairy farms, but for beef farms only if they achieved TB free herd status. Reducing the compensation level to zero did not alter the situation significantly. The net gain in dairy farms increased, the situation in the beef breeding farms changed minimally and on beef finishing farms the adoption of control programmes became beneficial if the number of TB animals was reduced at least by two, without achieving TB free status. The final stage of the project described in this thesis was the development and use of FarmORACLE, a whole-farm simulation model, that allows the user to combine knowledge about TB and its occurrence on farms with farm-specific grazing strategies. The model was used to compare traditional grazing strategies with alternative strategies, that excluded cattle and deer from grazing TB hot-spot paddocks during high-risk times. Four farms were described in detail. In all four farms an alternative grazing strategy was found that resulted in higher production or greater economic returns, while protecting the herd against exposure to tuberculous possums.