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Item Measurement and modelling of salt and nutrient dynamics under Salicornia irrigated with saline groundwater, desalination reject-brine, and aquabrine : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Soil and Environmental Sciences, School of Agriculture and Environment, Massey University, Palmerston North, New Zealand(Massey University, 2024-07-27) Al Tamimi, MansoorEnvironment Agency-Abu Dhabi (EAD) has implemented several scientific research projects with Plant and Food Research (PFR) New Zealand and OnlyFromNZ Limited (OFNZ) to determine the irrigation requirements for date palms, arid forestry, and field crops, for Law 5 which states that groundwater in the Emirate is the property of the Government which has the responsibility for management, organization and licensing the activities related to groundwater. The Government entity is EAD-Environment Agency of Abu Dhabi). can be implemented using sound scientific bases to protect the interests of all. This is a cooperation with external partners, plus both governmental and non-governmental agencies. These projects aimed to determine the irrigation requirements for date palms, forests, and field crops. While these projects have determined irrigation requirements, they have not, to date, addressed the environmental impacts of farming on groundwater quantity and quality. This Ph.D. research explored the trade-offs between improved technologies for the use of alternative water supplies, such as desalination brines, and the environmental consequences of brine re-use. The results will form part of the future solutions at the nexus among food, energy, and water in Abu Dhabi. This doctoral research builds on nearly a decade of scientific knowledge developed in collaboration with the New Zealand teams. It identifies the opportunities for reject brine from desalination units in aquaculture and halophytic agriculture, as well as the environmental consequences of the fate of this salt and nutrients. Measurements are critical to understand groundwater impacts and the benefits of using saline groundwater and brines from desalination plants to irrigate halophytes in hyper-arid environments. In 2020, a pilot trial was set up using irrigation with highly saline waters. However, two difficulties were encountered, and the pilot trial was a failure. The first part of the thesis describes how the practical challenges of the measurement technologies used in this saline environment were overcome. Further, experiments were then carried out to quantify the efficiency and impact of salt leaching in removing salt from the rootzone. Two years of field experimentation were undertaken to determine the economic productivity and environmental impact on groundwater of irrigating the halophyte Salicornia bigelovii with three types of saline waters in the hyper-arid United Arab Emirates. In the first year, the irrigation waters employed were groundwater (GW) at 25 dS m⁻¹, reverse-osmosis brine (RO) from a desalination unit at 40 dS m⁻¹, and Aquabrine (AQ) effluent from land-based aquaculture in tanks filled with RO brine, also at 40 dS m⁻¹. Bubblers (BUB), pressure-compensated drippers (PCD), or subsurface irrigation tape (SUB) were used to apply the three waters Salicornia fresh tip, harvest forage, and seed yields were highest for AQ applied through BUB, reaching 650 g m⁻². The dry forage yield with AQ through BUB was found to be 2-2.6 kg m⁻², compared to 1-2.3 kg m⁻² for the other irrigation waters and emitter devices. The highest water productivity WPI (kg m⁻³) across all three crop outputs resulted from Aquabrine applied by pressure-compensated drippers. Gross economic water productivity (GEWP₁, $ m⁻³) was assessed based solely on gross revenue. The highest GEWP₁, at US$5.8-6.2, was achieved with AQ applied through PCD and SUB, primarily due to revenue from fresh tips. Notably, the GEWP₁ significantly exceeded the cost of desalination at $1.5 m⁻³. Drainage and leaching were measured using fluxmeters. The greatest salt load into the groundwater, at 135-195 kg m⁻², was observed with BUB irrigation. For PCD and SUB, the salt load ranged between 14-36 kg m⁻². Simple mass-balance calculations of these salt loadings were then employed to predict the impact on the saline quality of aquifers. An exemplar loading of 75 kg m⁻² was used, resulting in a projected annual salinity rise of 2.6 dS m⁻¹ y⁻¹ for an aquifer with a saturated depth of 100 m. This significant increase in groundwater salinity would represent a continual decline in the resource's utility. This simple mass-balance arithmetic highlighted the need for modelling. New data from the following year’s experiments highlighted the economic value of using nitrogen-rich saline waters, either from groundwater or reject brines from desalination units, to irrigate the halophytic crop Salicornia bigelovii for food, fodder, and fuel in a hyper-arid environment. The greatest benefit was, again, achieved using pressure compensated drippers. Field measurements of drainage and leaching under the crop showed that, in sum, all of the salt, as well as the nitrogen drawn up from the groundwater were returned back to the aquifer as leachate. The only loss of water to the system was through crop evapotranspiration ET𝒸. A simple heuristic model of groundwater quantity and quality was developed to infer the environmental impacts of irrigating crops with saline and high-nitrate groundwater in a hyper-arid environment. The time-rise in solute concentration in groundwater is found to be a hyperbola. The parameters needed for this simple model are the fraction of the land above the aquifer that is irrigated, the initial depth of the saturated thickness of the aquifer, the saturated water content of the aquifer, and the annual rate of crop evapotranspiration. An indicator of the rate-of-rise in solute concentration, akin to a half-life, is the numbers of years to double the solute concentration in groundwater. This can be found as Ө hₒ /2 ET𝒸, where Ө is the saturated water content, hₒ is the original thickness of the saturated layer, and ET𝒸 is the annual rate of crop evapotranspiration. The general model is simple and straightforward to parameterise. It is easily understood and useful for assessing the impacts and trade-offs of policy and regulatory options. The knowledge gained from these experiments and the predictions resulting from the heuristic modelling have been used to highlight future needs to be addressed for the critical issues at the food-water-energy nexus in hyper-arid regions.Item Impacts of shocks and coping strategies of vegetable farm households in Sri Lanka during COVID-19 pandemic : a dissertation presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Agriculture and Rural Development at Massey University, Palmerston North, New Zealand(Massey University, 2024-11-22) Rathnayake, Sanduni Anuththara KumariOver time, smallholders in developing countries, including those in Sri Lanka, face a variety of shocks and develop coping strategies in response. The COVID-19 pandemic resulted in a novel shock to many farm households in developing countries, often negatively impacting their livelihoods. This exploratory qualitative case study provides a comprehensive study on the impact of the pandemic on Sri Lankan smallholder vegetable farm households and their coping strategies. Data were collected from vegetable farm households and key informants in Nuwaraeliya and Kandy districts, mainly using the interview method and data were analysed qualitatively. Vegetable farm households in Sri Lanka faced multiple, diverse shocks characterised by cumulative, consecutive, interrelated, and ongoing events during the pandemic. This mix of shocks resulted in various impacts on vegetable farm households, but the common outcome on all households was f inancial due, in the main, to increased household costs and decreased household income. Farm households that predominantly depended on income from vegetable selling and farm households that produced only specialised types of vegetables for specialised markets were more adversely affected than others. Smallholder vegetable farm households were diverse in circumstances, production and marketing systems, household capitals, reliance on vegetables as an income source and livelihood activity. At any point in time different strategies related to production, marketing and financial hardships were being used by farm households to respond to the impacts of shocks they experienced. However, there was no consistent mix of strategies. The poorest continued to borrow, while others relied on savings and assets and then started to borrow when resources were depleted. How similar strategies were implemented varied across households depending on the social networks of households. While acknowledging the benefit of diversification for farm households during shocks, this study also illustrates that diversification does not guarantee that it will support farm households in buffering the impacts during a wide-scale shock that extends over a long period. However, market diversification supports farm households to buffer the impacts of shocks with broad-scale impacts. This study also identified the significance of individual household members’ personal characteristics such as motivation and enthusiasm in developing strategies and argues for including this attribute in human capital in the sustainable livelihood framework. Research insights strongly suggest that interventions intended to support farm households in buffering the impacts of shocks need to focus on the household level, prioritising the poorest of the poor while remaining open to addressing the needs of other farm households who might be wealthier but adversely affected by shocks. Providing direct financial support and implementing different financial services to accommodate the varied circumstances of farm households will benefit them during shocks. Interventions to build household and local community resilience will safeguard farm households as it will exclude the risk of overreliance on external government support.Item Bananas grown in Aotearoa for feeding the infant gut microbiota : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biological Sciences at the College of Sciences, Massey University, Manawatū, New Zealand(Massey University, 2024) Frame, Simone FrancesThe human gut microbiota is established immediately at birth and thereafter is modulated by a range of environmental influences including the nutrients available within breast milk (and microbiota) or formula which support selective colonisation. Upon weaning to solid foods, the infant gut microbiota begins to become more akin to that of an adult in both microbial composition and metabolite production. Bananas are recommended by New Zealand health officials as an appropriate first food, however at present the only commercial variety available is Cavendish, imported largely from Ecuador and the Philippines. Although, in Northland and Gisborne regions other banana varieties are successfully cultivated, they have not been recognised by the commercial sector as valuable produce. Here we identify the nutritional composition of an array of banana cultivars grown in New Zealand, which are hybrids of acuminata (A) and balbisiana (B) species of banana and how these varieties impact SCFA production by the infant gut microbial population. We further identified the distinct shifts in microbial populations between three banana cultivar genome groups represented as AAA, AAB and ABB. Cavendish is AAA. Genomic mapping of unknown banana cultivars provided insight into the diversity of banana cultivars growing in New Zealand, in which the ecophysiology of bananas growing in this climate has presented different phenotypic characteristics to those of countries where banana horticulture is prevalent. These findings will contribute toward particularly, Māori communities building an emerging commercial banana industry and creating a nutritional database for New Zealand grown banana.Item Quantifying the spatial distribution of avocados for optimising yield estimation : a thesis presented in fulfilment of the requirements for the degree of Master of Engineering in Mechatronics at Massey University, Manawatū, New Zealand(Massey University, 2024) Williams, JackThis thesis addresses the need for accurate yield estimation in commercial avocado orchards, leveraging insights from prior research on AI technology for avocado counting. The literature review identified a gap in understanding the spatial distribution of avocado fruit, leading to the development of a 3D positional data collection methodology. In this project a coordinate mapping device employing a laser distance measure and high precision rotary encoders was developed, tested and later implemented in a commercial Hass avocado orchard, resulting in a unique 3D positional dataset of 2,909 measured avocados from 27 trees. The results provide valuable insights into how avocados are distributed on the trees, leading to recommendations for an ideal image capturing procedure. It was found that 98% of all fruit would be included in a field of view extending out to half the row spacing along the row direction and 2.4 m in any other direction from the tree's base. Challenges such as occlusion prompt the need for further research, including simulations and trials based on the collected dataset. Recommendations are made to guide future research towards refining image-capturing procedures for implementing image-processing AI, leading to efficient and accurate individual tree counts. These counting methods can be employed in conjunction with traditional or satellite-based block sampling techniques, facilitating an accurate overall block yield estimation and providing growers with the necessary insights to make informed commercial harvest decisions.Item Fertiliser management strategies for improving fruit nutrient composition and quality in Hass avocado : 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, 2024-09-13) Monserrate Rojas, Fredy AlexanderThe avocado industry has the third largest export value of the fruit flesh sector in New Zealand and is focused on exporting premium fruit quality (FQ). However, postharvest internal fruit rots, especially body rots (BR), are a significant issue for fruit harvested late in the season, when the demand from the main export markets is higher. Enhancing fruit nutrient composition, especially increasing Ca concentration and the Ca+Mg:K ratio, and decreasing the N:Ca ratio, has been associated with a lower incidence of internal fruit rots. This study involved a survey of commercial avocado orchards and a fertiliser field trial in the Bay of Plenty (BoP) Region. The study investigated the effects of nitrogen (N), potassium (K) and calcium (Ca) fertiliser practices on fruit nutrient composition and the production of unsound fruit during the late harvest, or fruit affected by any FQ disorder in 5% or more of their surface. Both components of the study showed a general decline in Ca concentrations in the flesh and skin of late harvest fruit. In the two-year field trial, the average Ca concentration decreased on average by ~50% in fruit flesh and ~16% in fruit skin, between the early (September) and late (January) harvests. The fruit Ca concentration decreased as the flesh dry matter increased from around 23% at the early harvest, to around 33% at late harvest. The decline in fruit flesh Ca concentration was the main factor influencing higher N:Ca ratios and lower Ca+Mg:K ratios in the late harvested fruit. However, in the fruit skin it was the combined effect of the lower Ca concentrations and higher N and K concentrations that resulted in higher N:Ca ratios and lower Ca+Mg:K ratios during the late harvest. Overall, the practice of keeping the avocado fruit on the tree until late harvest results in unfavourable changes in fruit nutrient ratios. The fruit Ca concentration did not increase with the soil exchangeable Ca concentration at any sampling in the commercial avocado orchards included in the survey study. In the field trial, which had a high initial soil exchangeable Ca concentration, the addition of calcium nitrate fertiliser before the early fruit set also did not increase fruit Ca concentrations at any harvest time. These results support the idea that under conditions of high soil Ca status (over 12 meq Ca/100g), which is common of high-performance avocado orchards in the BoP Region, additional Ca inputs have a negligible effect on fruit Ca concentration. Nitrogen fertiliser use was the main factor influencing changes in fruit N:Ca ratios and the production of unsound fruit due to internal fruit rots. In the field trial, the lowest N fertiliser rate of 50 kg N/ha/year decreased the skin N:Ca ratio by 22% and fruit unsoundness by 20% compared to the use of 150 kg N/ha/year, which resulted in the highest N:Ca ratio and fruit unsoundness. It is common for avocado orchards in the BoP Region to use N fertiliser rates greater than 100 kg N/ha/year. Therefore, it is likely that current N fertiliser use practices contribute to the observed unsoundness of fruit harvested late in the season due to internal fruit rots. Additional research is needed to assess lower N fertiliser rates, in the range of 50-100 kg N/ha/year, over an extended period and across different sites, to further validate and refine these N fertiliser recommendations. In addition, the strong correlation observed between the skin N:Ca ratio and fruit unsoundness in late harvested fruit confirmed its potential use as a suitable indicator of internal fruit rots. In the field trial, two fertiliser practices potentially reduced the severity of BR, the most common FQ disorder of late harvested fruit, compared to the 150 kg/ha/year of N and K that resulted in the highest BR severity. When N and K fertilisers were applied together at their lowest rates (50 kg/ha/year), the severity of highly affected fruit (BR severity >15%) by BR was reduced. In addition, the use of the lowest rate of N combined with the highest rate of K fertiliser (300 kg K/ha/year) reduced the severity of moderately (BR severity >5%) and highly affected fruit by BR. However, in orchards where soil K levels are already optimal, the application of high K rates may be inefficient and costly. In addition, fruit quality assessments in this study were not conducted on treatments that compared the lowest rate of N and more moderate rates of K, between 50 and 300 kg K/ha/year. Therefore, further research is needed to further refine these recommendations, including investigate a benefit from applying a higher proportion of the fertiliser K before fruit set.Item Rhododendron taxonomy and diversity of ex situ collections for conservation : (subsection) Maddenia species as a case study : a thesis presented in the partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Agriculture and Horticulture at Massey University (Manawatū campus], Palmerston North, New Zealand(Massey University, 2024-02-01) Hu, LingIn the ‘big genus’ Rhododendron of over 1,000 species, more than half of the species are threatened, at risk, or lacking data for biodiversity conservation. Ex situ collections, especially those from the wild, are crucial for safeguarding the diversity of species. However, lack of knowledge on existing wild diversity in botanic garden collections, and complex taxonomy, are two main problems in species assessments and conservation decision making. This research studied subsection Maddenia, a group of ~65 taxa encountering the two problems but seldom studied, as an exemplar to investigate species taxonomy and ex situ diversity. An ex situ conservation gap analysis was undertaken, using ecogeographical representation as a proxy for genetic representation in current botanic garden collections worldwide. Fifty-five of the total 65 taxa were found in cultivation, with over 86% of the living collections conserved in 66% of global botanic gardens. Half of the 18 threatened taxa, and nine of the 12 Data Deficient taxa require further wild collection to achieve a minimum level of ecogeographical representation in ex situ collections. Occurrence of ex situ collections in countries of origin is limited, and the distribution of ex situ collections worldwide is northern hemisphere centric. The results highlight the necessity of having more ex situ collections in the 10 native countries, and the importance of inter-institutional data sharing and robust documentation of collections. Determination of ploidy level of species was the second study, as the presence of polyploid samples may affect phylogenetic analysis. Ploidy levels were estimated for 263 accessions of 47 taxa (including 135 wild accessions) using flow cytometry. Meiotic chromosomes were counted for representative species of both diploids and polyploids to verify the flow cytometry results. This study showed that all taxa except one were diploid. The exception was that polyploids (2–8x, 12x) occur in the R. maddenii complex, where only seven of the 62 accessions tested were diploid while the rest were polyploid. This high level of polyploidy, combined with (i) the wide geographical distribution of the R. maddenii complex, and (ii) the previous ‘lumping’ of 12 taxa into the two subspecies, suggests the possibility of either some cryptic species or the need to re-evaluate some of the synonymized species. If new species were revealed, some may require conservation action. However, a greater number of wild-collected accessions and of different geographic origins are needed to explore this possibility. Following the ploidy study, molecular phylogeny of 40 taxa, including diploids and polyploids, was analysed using target capture sequencing. Phylogenetic trees from maximum likelihood and Bayesian analyses largely supported the morphological groupings of the Maddenii Series, Ciliicalyx Subseries and Megacalyx Subseries, but not the Ciliatum Subseries as classified by Davidian (1982). Of particular interest was the clustering in one clade of all of the R. maddenii complex, including all polyploid samples. This occurred irrespective of the method of analysis; however, there was no clear pattern of relationships to ploidy levels within the clade. The molecular phylogeny delimited several species and suggested a revision of the boundary of ‘subsection Maddenia’, although further research, to include a wider range of species, is needed to determine whether the new boundaries should be wider or narrower than before. The feasibility of using controlled pollination for safeguarding germplasm of prioritised species in ex situ collections was studied. Fruit set and seed germination identified the self- and cross-incompatibility of R. excellens (Vulnerable), which requires methods other than controlled pollination to conserve the intraspecific diversity in botanic gardens. R. dalhousiae var. dalhousiae (Least Concern), R. dalhousiae var. rhabdotum (Vulnerable), R. lindleyi (Least Concern), and R. nuttallii (Near Threatened) were both self- and cross-compatible, but the compatibility between self and cross pollinations differed from taxon to taxon and from accession to accession. These results suggest the choice of intraspecific pollination should be tested for each species before a programme of propagation is initiated. These aspects studied for subsection Maddenia can be immediately applied to conservation of this group of plants by working with the Global Conservation Consortium for Rhododendron. Meanwhile, the methods used here provide an exemplar for investigating other Rhododendron species or plant groups that encounter similar problems, to guide conservation efforts.Item Quantifying and reducing nitrogen leaching under intensive vegetable production in Horowhenua : 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, 2023-12-14) Avendaño Veas, Fernando AlejandroVegetable growers often need to apply relatively large quantities of nitrogen (N) fertiliser to successfully grow their crops, and this can lead to large losses of N via runoff and/or leaching to receiving water. Growers are under increasing pressure to reduce N leaching. Therefore, practices that increase N use efficiency and mitigate N losses are receiving increasing attention from growers, regulators, and scientists both in New Zealand and worldwide. For instance, high N levels have been observed in the Arawhata stream and Lake Horowhenua in the Arawhata catchment, where most of the fresh vegetables consumed in the lower North Island of New Zealand are grown. There is currently little research data available which quantifies N leaching from different practices of vegetable production systems in New Zealand, including for the Arawhata catchment. Therefore, the first objective of this study was to identify the likely range of N leaching rates under vegetable production in the Arawhata catchment. Nitrate-N in soil and N losses were measured under a series of crops at two field trial sites which were established on two local farms: a site with a potato-onion rotation (Potatoes site) and a site under a beetroot-Pak choi rotation (Green vegetables site). Soil nitrate-N was sampled at depths of 0-30 and 30-60 cm at the Potatoes site, and at 0-20 cm at the Green vegetables site. Mean soil nitrate-N in the topsoil (0-20 and 0-30 cm) ranged between 9.3 and 18.3 ppm, while mean soil nitrate-N in the subsoil (30-60 cm) ranged between 7.3 to 9.6 ppm. N leaching was measured using suction cups and lysimeters. Mean nitrate-N concentrations in soil water ranged between 16.9 to 61.9 mg L⁻¹, and N leaching ranged from 95 to 225 kg N ha⁻¹. These field measurements of N leaching were used to calibrate and validate the APSIM Next Generation model. APSIM simulates N dynamics, including leaching, under crops at the paddock scale. APSIM was then used to investigate N leaching rates under a wider range of climate conditions (31 years), the effect of soil type on leaching, and to quantify the ability of different mitigation strategies to reduce N losses under intensive vegetable farming in the region. The mitigation scenarios at the Potatoes site included: potato harvest at maturity and ryegrass cultivation during the drainage season, and potato harvest at maturity and cultivation of winter catch crops. The mitigation scenarios at the Green vegetables site included: potential of drainage management, a range of alternative cover crops and catch crops instead of ryegrass, and other crop rotations. These mitigation scenarios resulted in an N leaching reduction of 7 to 47% in the Potatoes site, and of 6 to 52% in the Green vegetables site. The final objective of this research was to evaluate the impact of field-scale mitigation measures on the Arawhata stream by coupling the N losses simulated in APSIM with a catchment-scale model (SWAT+). This simulation exercise suggested that by considering crop rotations that use less N fertiliser and frequently grow cover crops, N loads in the Arawhata stream could be reduced by 17% to 21%.Item Finding value in an alternative caring food network : a study of how localised regenerative small-scale growers can build social value in our food system : a thesis presented in partial fulfilment of the requirements for the degree of Master of Arts - Human Geography, Massey University, New Zealand(Massey University, 2022) McLeod, Heidi AnneThrough its significant dairy farming sector, Taranaki epitomises modernised food production and distribution within a global food system. Alongside this, a burgeoning community of small-scale growers exist who do not aspire to large scales or optimised profitability. These growers support localised food production, diversity in distribution, regenerative practices, and caring social values. I argue they are fundamentally 'resocialising' food in a way that enhances social, cultural and economic values, and are creating wellbeing for local communities through an ethic of care. There is little literature regarding the social attributes of food grown by small-scale growers for local consumption. This thesis aims to contribute to that body of work by offering an ethnographic account of small-scale growers. I argue that these growers build and strengthen a sense of community thereby creating an interconnected web of organised care relationships that form a 'meshwork', connecting people to place within Taranaki. I will show that understanding the relationship between people and food procurement goes beyond a financial exchange, disentangling food from a global food system where it may be 'food from nowhere' to situating it in a localised setting where through processes of resocialisation, it becomes 'food from somewhere' (McMichael, 2016). However, despite creating positive social values, small-scale growers struggle to hold their space within the global food system because they are frequently deprioritised, undervalued, or unrecognised. This thesis concludes by showing Taranaki’s regenerative small-scale growers are able to create a meshwork of food production and distribution that resocialises food through values of care.Item The effect of nitrogen fertiliser on the sensometabolomic profile of steamed potatoes : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Horticultural Science at Massey University, Manawatu, New Zealand(Massey University, 2020) Ross, Sarah BeatrixFor growers of high-value potatoes (Solanum tuberosum L.), flavour is an important product characteristic to consider, as a driver of consumer purchasing behaviour. Recent potato flavour research has focused on combining sensory and analytical techniques to better understand flavour. However, there is a lack of understanding around the relationship between consumer flavour preferences and flavour-related composition. In addition, there is very little known about the impact of agronomic factors on these aspects combined. For nitrogen, a nutrient of concern in New Zealand because of its environmental implications, understanding on how different rates of nitrogen fertiliser affect flavour is limited. Therefore, this study used a combined approach of consumer sensory evaluation with metabolite testing (sensometabolomics) to determine if nitrogen fertiliser affects the perception of steamed gourmet potato flavour and composition. Two potato varieties, ‘Annabelle’ and ‘Andean Sunside’, were treated with three different rates of nitrogen fertiliser during crop growth: 0 kg N ha⁻¹, 150 kg N ha⁻¹, and 300 kg N ha⁻¹. One hundred and eleven regular potato consumers assessed steamed potato samples for liking, using a labelled affective magnitude scale, and flavour, using rate-all-that-apply, across 14 flavour attributes. The levels of key flavour-related metabolites and variables were measured in the same potatoes, including dry matter, sugars, glycoalkaloids, polyphenols, umami amino acids, total nitrogen, nitrate, and volatile compounds. Principal component analysis was used to assess the association between changes in composition and flavour. Nitrogen fertilisation significantly affected composition and flavour in Annabelle and Andean Sunside, and ranked liking in Andean Sunside. In both Annabelle and Andean Sun- side, total nitrogen, asparagine, and glutamine levels significantly increased with the rate of nitrogen fertiliser applied, from 0 kg N ha⁻¹ to 300 kg N ha⁻¹. In Annabelle alone, nitrate, 2- butanone, 2-methyl-2-(E)-butenal, methional, and benzaldehyde increased with nitrogen, while dry matter and both α-solanine and α-chaconine concentrations decreased. The effect of fertiliser on β-ocimene was variable. In Andean Sunside, α-solanine, β-ocimene, and phenethyl alcohol all increased with nitrogen supply, while glucose and fructose con- centrations significantly decreased. Levels of (Z)-hex-3-en-1-ol, linalool, and benzyl alcohol significantly increased between 0 and 150 kg N ha⁻¹ treatments. The effect of nitrogen on quercetin-3-rutinoside was inconsistent in Andean Sunside. While average liking was not significantly affected by nitrogen, Andean Sunside 0 kg N ha⁻¹ samples were ranked significantly higher in liking compared to 300 kg N ha⁻¹ samples. Overall, nitrogen fertilisation appeared to slightly, but significantly, increase the intensity of attributes with more negative associations. Annabelle 300 kg N ha⁻¹ samples contained significantly higher intensities of nutty, musty, and sour attributes, while Andean Sunside 0 kg N ha⁻¹ samples were significantly more buttery, and less cardboard and green grass- flavoured, compared to 150 kg N ha⁻¹ samples. Therefore, for Annabelle, either 0 and 150 kg N ha⁻¹ treatments were recommended to reduce the intensity of off-flavoured attributes. For Andean Sunside, decreasing the rate of nitrogen applied was recommended to reduce the intensity of off-flavours and increase the intensity of buttery flavour, as observed in 0 kg N ha⁻¹ samples. Changes in composition could not be associated with changes in perceived flavour, within the varieties and treatments used in this study.