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Item Investigating the health benefits of Monty’s Surprise apple phytochemicals : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science at Massey University, Manawatū, New Zealand. EMBARGOED until 18 November 2027.(Massey University, 2024) Nezbedová, LindaCancer is a major health concern worldwide, requiring effective prevention strategies to reduce its burden. There is evidence suggesting that diet plays an important role in disease prevention. Apples are an example of a commonly available fruit that can be easily incorporated into a diet to reduce the risk of chronic disease and some cancers. Apples are rich in phytochemicals with chemo-preventative properties. However, assessing their benefits in humans is complex due to various factors affecting phytochemical composition and low bioavailability. Understanding and controlling for these factors is crucial for maximising their potential in preventing cancer and promoting human health. The PhD project presented in this thesis uses a multidisciplinary ‘from orchard to fork to function’ approach to evaluate the health benefits of phytochemicals in a New Zealand heritage apple cultivar known as Monty’s Surprise, with an emphasis on cancer prevention. This thesis particularly focuses on apple’s most abundant phytochemical group known as phenolic compounds. After controlling fruit harvest and maturity, Monty’s Surprise apple was found to contain high concentrations of health beneficial phenolics, especially procyanidins, with apple skin having higher total phenolic content compared to its flesh. Pureeing was identified as a suitable processing technique with minimal impact on apple’s phenolics, allowing long-term preservation and creating uniform material for use in intervention and feeding trials. Moreover, Monty’s Surprise apple extract depleted of sugars inhibited the proliferation of lung, breast, and colorectal cancer cells in a dose-dependent manner in vitro. Lastly, in a human acute feeding trial, Monty’s Surprise apple puree increased plasma antioxidant capacity and decreased postprandial glucose response compared to sugar-matched placebo. The feeding trial also showed that procyanidins were not detected in the participant’s blood, while epicatechin and chlorogenic acid, which are prevalent phenolics in Monty’s Surprise apple puree, were absorbed into the bloodstream. Therefore, these compounds were available to contribute to the improved health parameters measured in the study. This study offers practical recommendations for optimising harvesting, storage, and processing practices to preserve and more clearly elucidate the health-promoting properties of phenolics in apples. Overall, this research demonstrated the potential health benefits of Monty’s Surprise apple and its phenolics, suggesting its value as a functional food for improving human health and well-being.Item Value added wheat through applied genomic prediction : a genomic approach for breeding low gluten epitope wheat : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Breeding and Genetics at Massey University, Palmerston North, New Zealand. EMBARGOED until 24 July 2026.(Massey University, 2023) Macalister, JamieGluten epitopes are known to trigger coeliac disease (CD) in affected consumers and are believed to be linked to some cases of gluten intolerance. Research suggests that if consumers were exposed to wheat with reduced concentrations of gluten epitopes, the incidence of CD and gluten intolerance may be reduced. Methods have recently been developed allowing researchers to measure gluten epitope concentrations in wheat. This offers wheat breeders the potential to select towards varieties with lower epitope concentrations than existing cultivars. However, the methods for measuring epitope concentrations remain costly and time consuming. Therefore, it is proposed that a genomic based approach for breeding low epitope wheat lines is a more practical method than traditional phenotype-based selections. The genetic factors associated with epitope concentrations remain poorly understood. In this thesis, heritability estimates of between 0.37-0.93 are reported for concentrations of 6 distinct gluten epitopes. The associations between epitope concentrations and baking quality are also assessed and are shown to range from being near zero for some epitopes to strong positive correlations between other epitopes and particular baking quality characteristics. A Genome Wide Association Study and a model for genomic prediction are employed to determine the genetic factors associated with epitope concentrations. In these analyses, 3 significant genomic windows are identified as being associated with concentrations of 3 particular epitopes. Empirical prediction accuracies of between 0.16-0.53 are observed for predictions of epitope concentrations in a breeding population. Additionally, accuracies of between 0.37-0.67 are achieved by adjusting the population structure to represent the ideal circumstances that breeders would aim to achieve in their training and target populations. These results demonstrate that genomic selection (GS) will be an effective method for breeding low gluten epitope wheat. The outcome of this thesis will allow implementation of GS in the New Zealand Institute for Plant & Food Research wheat breeding program where epitope concentrations will be established as a new breeding target. This is expected to lead to the release of niche, low epitope cultivars with a value-add component that benefits growers, industry and consumers.Item Towards better New Zealand adapted industrial hemp (Cannabis sativa L.) cultivars : a quantitative genetic analysis of key traits and evaluation of genetic diversity : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Manawatu, New Zealand(Massey Library, 2023-09-12) Komahan, Dona Harshani ShanikaHemp (Cannabis sativa L.) is emerging as a promising commercial crop in New Zealand. Breeding programmes developing material specifically adapted to the country’s target population of environments are at their early stages of establishment. With 20 approved hemp cultivars, 15 of which are imported, it is vital to prioritize research and development focused on the genetic improvement of hemp to generate cultivars that are well adapted to New Zealand’s crop production environments, offering both economic and agronomic benefits. The primary aim of this thesis is to lay the foundation for future hemp breeding in New Zealand by focusing on three critical initial steps: (1) conducting multi-site trials to evaluate the performance of commercial hemp cultivars based on key traits and characterize the effects of Genotype × Environment interaction (G × E interaction), (2) estimating quantitative genetic parameters and predicting genetic gain for key traits to identify breeding strategies that would improve the efficiency of maximizing genetic gain, and (3) assessing genetic diversity using molecular markers and characterizing available genetic resources. These steps are crucial for developing new cultivars that are both climate-resilient and beneficial to New Zealand’s hemp industry. Multi-site trials were conducted for two years over the 2019/2020 and 2020/2021 growing seasons using six hemp cultivars approved to be grown in New Zealand: CFX-2, CRS-1, Ferimon 12, Katani, Futura 75, and Finola. The 2019/2020 trials were conducted in Palmerston North and Wairarapa, while the 2020/2021 trials were conducted at two nearby sites in Palmerston North with different soil characteristics. Across both multi-site trials, biomass yields extend over a broad range from 1.43 to 28.41 t/ha, and seed yields ranged between 0.018 and 3.78 t/ha. The study’s findings on G × E interactions showed a complex scenario that mostly differed from prior reported research. Although significant (P < 0.05) genotypic variation was observed in most traits, only a few, specifically stand establishment in the 2019/2020 season, along with plant height and stem diameter in the 2020/2021 growing season and biomass yield across both years, showed significant (P < 0.05) G × E interactions, suggesting consistent performance across sites. The traits plant height, stem diameter, biomass yield, seed yield, and thousand seed weight have all revealed high cultivar mean broad sense heritability, indicating potential exploitable underlaying genetic variation that could be used to generate breeding pools for cultivar development. A quantitative genetic analysis was conducted using 50 half-sib families (HS families) focused on six key traits: stem diameter, plant height, number of internodes, seed yield, thousand seed weight, and biomass yield to investigate the magnitude of additive genetic variation within a breeding population. The study also aimed to predict the rate of genetic gain for these traits. Significant (P < 0.05) additive genetic variation was observed among the 50 HS families for traits: seed yield, biomass yield, stem diameter, plant height, and the number of internodes, highlighting each trait’s additive genetic variation available for breeding. Deterministic simulation of the breeding strategies, among HS family selection (AF-HS) and among- and within-family selection (AWF-HS), was conducted to predict genetic gain for these traits. AWF-HS yielded the highest genetic gains compared to AF-HS. The study estimated moderate to strong positive genetic correlations among all traits, generally higher than the phenotypic estimates. The genetic correlation coefficients suggest that genotypes with higher seed and biomass yields can be developed. There was significant (P < 0.05) differences between some HS families and the two commercial check cultivars, Fasamo and Férimon 12. HS families outperforming these commercial checks were identified. A laboratory experiment examined the genetic diversity and the degree of variability within and among six New Zealand-approved hemp cultivars using seven previously developed microsatellite (SSR) markers. STRUCTURE analysis identified two distinct genetic clusters that align with the plant’s reproductive biology (monoecious and dioecious), that further subdivided based on end-use (fibre, seed, fibre and seed, and CBD cultivars). The genetic diversity metrics revealed moderate genetic diversity among the six hemp cultivars. The average observed heterozygosity (Ho) and the expected heterozygosity (He) were 0.44 and 0.50, respectively. The Wright’s fixation index (FIS) varied from 0.26 (Futura 75) to -0.02 (Finola). The Analysis of Molecular Variance (AMOVA) revealed that a large portion of the total genetic diversity was found within individual cultivars. While only 11% of the molecular variation was attributed to differences among the cultivars, 19% was attributed to variations among individuals within each cultivar. Notably, the genetic variation within individual plants (69%) exceeded the variation observed both among individuals and among different cultivars. Additionally, considerable molecular variation was observed between male and female individuals of dioecious hemp cultivars. The genetic diversity metrics of female and male groups indicated that female individuals possess greater variation than their male counterparts. Collectively, results from this Ph.D. study lay the groundwork for future hemp breeding research and development in New Zealand. They provide an initial resource, offering insights into genetic diversity, genotypic variation, and the impact of G × E interactions on key traits evaluated among six introduced offshore cultivars. Furthermore, the estimates of quantitative genetic parameters add value to the existing knowledge base, enhancing the development of hemp cultivars suited to New Zealand crop production environments.Item Plant germplasm diversification strategies : a case study using Limonium : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Palmerston North, New Zealand(Massey University, 2024) Cordoba-Sanchez, JuanaLimonium Mill. was chosen for this research as it has an established market for ornamental use and faces significant challenges in breeding including access to germplasm with traits of interest, self-incompatibility in most species, and pollen/stigma dimorphism which limits the types of cross combinations that can be performed. In interspecific crosses, challenges can be the low hybridisation rate (<1%), and the sterility/low fertility of interspecific hybrids. To address these challenges, increase the germplasm diversity available, and speed the development of cultivars, two breeding strategies were evaluated in this research: ploidy manipulation and physically induced mutations. The main outcomes were: 1. Efficacy of those strategies in: • Increasing the ploidy levels of the selected genotypes and therefore the germplasm diversity for The New Zealand Institute for Plant & Food Research Ltd (PFR)’s germplasm bank. • Increasing the hybridisation rate in interspecific crosses. • Fertility restoration in interspecific hybrids 2. Development of plants with new characteristics or different ploidy levels (i.e., triploids, tetraploids, or even higher ploidy levels). 3. Breeding protocols for Limonium using N2O which could be further used in other plant breeding programmes. The use of Limonium for the development of a new breeding strategies for increasing genetic diversity has a direct impact on other breeding programmes i.e., food crops. In addition, the Limonium industry could have access to continued novelty, ensuring industry access to new cultivars would benefit New Zealand’s economy mainly through royalties.Item Investigation of tropical pasture species to improve dairying in the tropics : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Manawatū, New Zealand(Massey University, 2023) Jayasinghe Mudiyanselage, Priyanath JayasingheDespite the ever-increasing demand for dairy products, dairy production in tropical regions is often lower than in temperate regions, due to a range of factors including the lower nutritive value of pastures. The availability of high-quality tropical pastures is a key requirement to increase the productivity of dairy cows as well as manage enteric methane emissions. Warm-season perennial grasses are the dominant forages in tropical and subtropical regions, and thus exploring their nutritive characteristics and evaluating their likely performance in existing dairy production systems, is imperative in the effort to improve dairy productivity. This thesis was undertaken to investigate tropical pasture species for improving dairying in the tropics via a modelling and simulation approach. A dearth of data comparing the nutritive values of tropical pastures grown across different environments limits the selection of forages for livestock in the tropics. A database was constructed containing a total of 4750 records, with 1277 measurements of nutritive values representing 56 tropical pasture species and hybrid cultivars grown in 26 different locations in 16 countries, in order to compare the nutritive values and greenhouse gas production across different forage species, climatic zones, and defoliation management regimes. The average edaphoclimatic (with minimum and maximum values) conditions within this data set were characterized as 22.5°C temperature (range 17.5–29.30°C), 1253.9 mm rainfall (range 104.5–3390.0 mm), 582.6 m elevation (range 15–2393 m), and a soil pH of 5.6 (range 4.6–7.0). The data revealed spatial variability in nutritive metrics across bioclimatic zones and between and within species. The ranges of these nutrients were as follows: neutral detergent fibre (NDF) 50.9–79.8%, acid detergent fibre (ADF) 24.7–57.4%, crude protein (CP) 2.1–21.1%, dry matter (DM) digestibility 30.2–70.1%, metabolisable energy (ME) 3.4–9.7 MJ kg⁻¹ DM, with methane (CH₄) production at 132.9–133.3 g animal⁻¹ day⁻¹. The arid/dry zone recorded the highest DM yield, with decreased CP and high fibre components and minerals. Furthermore, the data revealed that climate, defoliation frequency and intensity, in addition to their interactions, have a significant effect on tropical pasture nutritive values and CH₄ production. Overall, hybrid and newer tropical cultivars performed well across different climates, with small variations in herbage nutritive value. Results revealed that greater pasture nutritive values and lower CH₄ production can be potentially achieved through the selection of improved pastures and subsequent management. Subsequently, the suitability of three improved tropical perennial pastures: Chloris gayana ‘Rhodes grass cv. Reclaimer’ (RR), Megathyrsus maximus ‘Gatton Panic’ (GP), and Brachiaria ruziziensis x B. decumbens x B. brizantha ‘Brachiaria Mulato II’ (BM) for tropical dairy production was evaluated using their carbon assimilation, canopy structure, herbage plant-part accumulation and nutritive value parameters under irrigated conditions. A field experiment was conducted at Gatton Research Dairy (27° 54′ S, 152°33′ E, 89 m asl) Queensland, Australia, which has a predominantly subtropical climate. Photosynthesis biochemistry, canopy structure, herbage accumulation, plant-part composition, and nutritive value were evaluated. Photosynthesis biochemistry differed between pasture species. The efficiency of CO₂ assimilation was highest for GP and quantum efficiency was highest for BM. Pasture canopy structure was significantly affected by an interaction between pasture species and harvest. Forage biomass accumulation was highest in GP, while BM produced more leaves and less stem compared to both GP and RR. A greater leafy stratum and lower stemmy stratum depth were observed in the vertical sward structure of BM. Brachiaria Mulato II showed greater carbon partitioning to leaves, leaf: stem ratio, canopy, and leaf bulk density. The BM also demonstrated greater nutritive value (Total digestible nutrients (TDN), ADF, NDF, neutral detergent insoluble protein (NDICP), starch, non-fibre carbohydrates (NFC), ME, mineral profile (Mg, P, K, Fe, Zn) and dietary cation-anion difference (DCAD)) for leaf, stem, and the whole plant. Overall, the observed greater quantum efficiency, leaf accumulation, and nutritive value of BM suggested that BM is an attractive forage option for dairying in pasture-based systems in tropical and subtropical climates. The DairyMod-SGS, a mechanistic biophysical pasture model was parametrised and robustly validated for the prediction of the growth of the three tropical pastures (BM, GP, and RR), aiming to use the model as an effective tool to explore the likely performances of newer species under different edaphoclimatic and agronomic management practices. The model was calibrated using measurements of biomass components, canopy structure, and carbon assimilation collected from the field experiment at the Gatton Research Dairy Farm. Subsequently, the model was tested extensively using the published and unpublished data (16 data sets, 32 experiments, 14 different locations across South America, North America, Australia and Africa) to ensure that the parameterised model performed well and was reliable across a diverse set of environments and management practices. In the model parameterisation stage, the model predicted the above-ground biomass with good agreement for all tropical pastures with a high R² of 0.92, 0.98, 0.74 and low RMSE of 341, 583, 848 kg DM ha⁻¹ for BM, GP, and RR, respectively. The model agreement was good for the validation data with R² of 0.86, 0.80, 0.87 and RMSE of 954.5, 790.5, and 633.2 kg DM ha⁻¹ for BM, GP, and RR, respectively. The predicted leaf and stem partitioning was relatively poor, and the model also struggled to simulate realistic pasture growth in Mediterranean and desert environments (R² < 0.50). The present study has improved the robustness and accuracy of DairyMod-SGS in relation to tropical pastures and indicated that the model can be successfully used for investigating the likely performance of improved tropical pastures under a broad range of conditions. The validated DairyMod-SGS pasture model was applied to simulate the long-term pasture production of three improved pastures (BM, GP, and RR) in major dairying regions of Sri Lanka under three management scenarios: 1) rainfed pasture production system under the industry average nitrogen (N) fertiliser rate (Yₜᵂᴺ = yield over time under water and N limitation); 2) rainfed pasture production system under non-limiting N fertilisation (Yₜᵂ = yield over time with no N limitation but water limitation); and 3) potential pasture production system under non-limiting N and irrigation (Yₜ = yield over time with no N and water limitations). Simulations were carried out for 16 sites across Sri Lanka (8 sites in the dry zone (DZ), 5 sites in the intermediate zone (IZ), and 3 sites in the wet zone (WZ)) over a 30-years period (1980–2010). The model simulated that the long-term pasture production greatly varied between climate zones, pasture species and management scenarios. Overall, the Yₜᵂᴺ scenario showed a seasonal cycle following the rainfall pattern, with a reduction in growth rates in dry seasons (May to September). Growth rate and herbage accumulation were greater in GP at Yₜᵂᴺ, and BM at Yₜᵂ and Yₜ, while RR always showed the lowest growth rate. The variability of pasture growth between climate zones was highest in DZ (May to September) whereas the variability between species was lowest in RR. Pasture accumulation of both BM and GP outperformed their standard cultivars currently grown in Sri Lanka. In general, the pasture accumulation under Yₜᵂ increased (doubled) the growth rate, while the Yₜ scenario substantially increased (nearly tripled) the growth rate. Overall, the finding of this thesis suggested that all three pasture cultivars tested (BM, GP, and RR) are suitable for growing across major dairying regions in Sri Lanka, and that appropriate fertiliser and irrigation management can greatly intensify the herbage accumulation. In particular, BM appeared to be promising in terms of nutritive value, and agronomic and physiological traits. However, regional edaphic conditions, and the management ability of the farmers with respect to inputs and defoliation management, will ultimately determine the performance of improved cultivars such as those used in this thesis. There is a need for extension activities to support farmers in the management required to achieve best performance (yield, nutritive value and persistence) from these species. Future research is recommended to: 1) validate the model under Sri Lankan conditions, using both unimproved and improved cultivars, to determine its suitability in estimating tropical pasture yield; and 2) use additional models to evaluate the performance of improved tropical pastures in the context of the whole farm system, to identify the likely impact on dairy production and economic return.Item The effects of defoliation and rootpruning on cocksfoot and perennial ryegrass and the influence of soil moisture on root initiation : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Field Husbandry, University of New Zealand(Massey University, 1949) Edmond, D. B.The world is short of food (1). The population of the world is unequally distributed in relation to the productive ability of the land. Countries, where an extension of the farmed area is possible, are handicapped by a lack of available labour. In general these are the countries where production has not, as yet, reached a maximum level. As labour hinders extension an endeavour must be made to utilise present farm areas in the most efficient manner possible, In this way surpluses of food may be accumulated in these countries, e.g. New Zealand, for despatch to needy areas where the consumption of food is at a low level. New Zealand produces animal products in quantity. To increase this quantity better use must be made of our chief stock food - grass. By more efficient use of our grasslands the production of our existing herds and flocks will be increased. while an increase in our animal population will be inevitable. [From Introduction]Item Seasonal root changes and their relationships to leaf production and persistency of growth in some grasses and clovers : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Field Husbandry at Massey University, by 550 [D.E. Yen](Massey University, 1947) Yen, D. E.The seasonal behaviour of pasture plant species is of fundamental importance to the farmer as one of the indices of value of any particular species, and the uses to which it can be put; and to the plant breeder, since it is his primary object to produce pasture plants which suit the farmer under his particular system of farming. To illustrate this point specifically, the example of the ideals aimed at in the breeding of short rotation ryegrass in New Zealand may be cited. Quoting Levy (1945), "... Italian ryegrass is a one- to two-year plant for the temporary pasture, and the true perennial ryegrass can be used widely in rotational and permanent pastures. There is, however, too large a gap between true perennial ryegrass and true Italian ryegrass, and many years of breeding and selection within these species accentuated the gap rather than reduced it." It can be seen that the short rotation system of farming, incorporating pasture leys of 3-4 years was not well served in the choice of a suitable ryegrass. Thus the plant breeding section of the Grasslands Division (Department of Scientific and Industrial Research) turned its attention towards breeding by hybridisation of perennial and Italian ryegrass, a type that would possess as far as possible the desirable qualities of these two species in combination; that is, it would combine some of the rapid establishment, high winter and early spring growth and palatability of Italian ryegrass with an appreciable degree of persistency of perennial ryegrass. Seasonal growth thus played the major part in the objectives of the resultant programme from which short rotation ryegrass was produced. Comparative trials of yields of the three grasses, perennial, Italian and short rotation ryegrasses were conducted in different localities, serving a very important purpose in providing farmers with direct information regarding the seasonal characteristics of production of the new type. These trials, which are continuing, show that short rotation ryegrass conforms largely to the objectives aimed at, so that the requirement s of the man farming under short rotation system have been met, to a great extent, by the work of the plant breeder. [From Introduction]Item A study of vegetative and reproductive development in Caucasian clover (Trifolium ambiguum, M. Bieb.) cv. Monaro : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science in Seed Technology at Massey University, Palmerston North, New Zealand(Massey University, 1993) Efendi, FahamA four year established stand of Caucasian clover (Trifolium ambiguum,M.Bieb) cv. Monaro grown on Fine Sandy Loam with moderate fertility was studied to assess the vegetative and reproductive development and the effect of defoliation on seed yield and yield components from September 1991 to June 1992. As in many other traditional herbage legumes, an indeterminate growth habit and a protracted flowering period can be a factor limiting seed production in this clover. From the examination of the vegetative growth and flowering behaviour, it was found that the protracted flowering pattern in this clover is mainly caused by continuous production of reproductive shoots from the crowns rather than continuing inflorescence emergence in one stem as results indicated that inflorescences produced were mainly associated with the number of reproductive shoots available at the time of inflorescence emergence. Reproductive growth commenced at the beginning of October when most visible . Inflorescence buds were formed and subsequent flowering occurred about 8 weeks later. This reproductive growth was found to be the most concentrated on reproductive shoots/stems formed in November to December 1991. These reproductive shoots contributed the majority (70%) of proportion to total inflorescences. Inter-row cultivation decreased the number of reproductive shoots produced as well as decreasing the number of inflorescences at harvest. Inflorescences originating from main crowns produced a higher number of floret buds and seeds per inflorescence than those originating from secondary crowns as the main crowns have their own strong taproot system and are more mature. Throughout the flowering season, T. ambiguum consistently abort about 10 % flower buds before the flowers open. On average of 60% of the open florets developed into live pods at maturity, but only one from two ovules in an ovary usually developed into seeds. On average of about 72% of pods had one seed, 11% of pods with two seeds and 16% were without seed. Both in early and middle flowers, seed development studies revealed that maximum yield of high quality seed was obtained only when seeds attained their maximum dry weight at 30 days after pollination, at the time when seed moisture content had fallen to 30 to 40%. At this time the pods were yellowish brown in colour. To ensure the production of good quality seed with high yield in T. ambiguum it is necessary, therefore to wait crop until at least 34 days after pollination for harvesting the seeds. Seeds harvested early at day 14 to 22 did not retain their viability suggesting that these seeds was still immature and could not withstand desiccation. It was found that pod shattering begun at about 8 days after maximum dry weight (mass maturity) was reached. Heavy rainfall and strong dry wind was found to enhance the rate of shattering. Hardseededness was observed firstly in freshly harvested seeds when seed moisture contents were close to 20%. The levels of hardseededness was higher after drying. Inflorescences set later in the season produced more hard seeds due to higher temperatures and increased humidity during maturation stage. The results of this experiment have confirmed the high seeding potential of T. ambiguum (cv. Monaro) and this should facilitate the production of adequate seed supplies of this cultivars. The average seed yield potential, potential harvestable seed yield and actual seed yield was 893 kg/ha, 707 kg/ha and 427 kg/ha respectively. This might be attributed to the facts that the crop examined in this study was a four year established sward which was mature enough to produced a high yield. Another study was done involving late defoliation treatments designed to investigate their possible effects on plant growth and seed production. Cutting the plant to the ground level showed an obvious harmful effects on seed yield in T. ambiguum. The results show that October and November cutting resulted a 67 and 72% decrease in actual seed yield compared to uncut control. This results support Steiner's view (in press) that the plant morphology of T. ambiguum limits its ability to recover from defoliation.Item Examining perennial ryegrass (Lolium perenne L.) persistence through identifying genetic shifts within two cultivars after nine years in the field : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Plant Breeding at Massey University, Palmerston North, New Zealand(Massey University, 2019) O'Connor, Jessica RichellePerennial ryegrass (Lolium perenne L.) is a commercially important forage species in New Zealand agriculture. Ryegrass persistence is important for farmers as it substantially decreases the costs associated with reseeding pastures. Breeding for ryegrass persistence is difficult because of the complex interaction between genotype and environment; and the short time of field trial assessment compared to the expected longevity of pasture. A nine year old cultivar comparison trial at Poukawa, Hawkes Bay, New Zealand was identified and plants surviving in the cultivar plots of ‘Grasslands Samson’ and ‘Commando’ were retrieved. These populations that had survived were termed Persistent. A sample of commercially sourced seed of these cultivars were also grown to represent the ‘Original’ genetic pool of the cultivars sown in the field. Persistent populations were compared to Original cultivar seed to characterise morphology and underlying genetics associated with persistence. Results were interpreted to determine if a genetic shift had occurred in Persistent populations due to advantageous phenotypes surviving. Three methodologies were used to compare populations: 1) In a glasshouse, eight morphological traits were measured after 10 weeks growth for Original and Persistent populations of ‘Grasslands Samson’; 2) Half-sibling families were generated from Persistent and Original populations for both cultivars and were assessed for additive genetic variation of seven traits as one metre rows in the field over 13 months; 3) Simple sequence repeat (SSR) markers were used to explore the genetic composition of Original and Persistent populations of each cultivar. Analysis and interpretation of data showed genetic shifts were cultivar specific. The greatest differences were identified between populations of ‘Grasslands Samson’. Compared to the Samson Original population, Samson Persistent plants had significantly greater means for four traits in the glasshouse and half-sibling families showed evidence of shifting population means of traits associated with animal grazing avoidance. SSR marker results were confounded by late detection of contamination in samples. Analysis of a reduced sample size showed no significant differences between any of the four populations using F statistics and genetic structure analysis. These results suggest future studies could reduce risk of contamination by collecting single tillers from the field of Persistent populations. Further investigation of the genetics of persistence should focus on the role of lamina sheath lengths in tiller production, and using the half-sibling families identified in this study for germplasm development and quantification of genotype-by-environment interactions.Item Limonium hybrid production and post-pollination biology : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Botany at Massey University(Massey University, 1995) Watson, Ian NThe aim of this thesis is to determine barriers to interspecific hybridisation in selected Limonium species. Production of new commercially viable hybrids is essential to the development of the Limonium cut flower market. Very few studies have been published with respect to pollination and post-pollination biology of this genus so this study contributes a better understanding of events leading to fertilization and some of the factors involved in interspecific hybrid production. The thesis initially introduces the genus and its cultivation. Later chapters involve aspects of post-pollination biology and determination of normal development associated with fertilization, including pollen tube growth, ovary and ovule growth and embryo production. This information is used to judge the success, barriers and problem associated with new hybrid Limonium production. Interspecific hybrids were not obtained, but the information provided serves to highlight difficulties in hybrid production and provides opportunities for more directed breeding programmes.
