Pacific and Pasifika Theses

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/4764

The theses listed in this collection were all completed at Massey University in a range of different departments and institutes. They have been included in this collection if the topic is strongly related to Pasifika/the Pacific.

Browse

Filters

2019 - 201912020 - 20211

Settings

Subject: search.filters.subject.Nutrition

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Development of sustainable nutrient management strategies for taro growers on Taveuni Island, Fiji : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science, Massey University, Palmerston North, New Zealand
    (Massey University, 2021) Lal, Rohit
    Taro (Colocasia esculenta) is a major component of the socio-cultural, dietary and economic livelihood of Pacific Island countries, including Fiji. However, Fiji’s total taro exports have substantially declined over the last decade, mainly due to a reduction in production from Taveuni Island. A trend of decreasing taro yields has been further exasperated by recent extreme climate events, which have reduced the availability and affordability of planting material. The combination of lower yields and increased costs, have reduced farmers’ returns on existing farm land, which has contributed to further deforestation of forest reserves. The overall aim of this study was to develop improved nutrient management practices on existing farm land, to help growers to achieve sustainable taro yields and financial returns. This study included a survey of 73 taro farmers, which involved a quantitative analysis of taro yields and soil fertility. Fresh taro corm yields were very low, being an average of 6.9 t/ha. About 75% of the farms surveyed had low soil Olsen phosphorus (P) levels of < 10 mg/kg and 65% had low soil exchangeable potassium (K) levels of < 0.4 me/100g. Fertiliser nutrient inputs were also low, with semi-commercial farmers using an average of 31 kg nitrogen (N), 17 kg P and 27 kg K/ha, and commercial growers using an average of 41 kg N, 26 kg P and 40 kg K/ha per crop. The survey also identified that fertiliser placement and application timing practices may also reduce nutrient use efficiency by the crop. Two successive field experiments were repeated over three sites, on Taveuni Island, to evaluate a range of nutrient management strategies to improve soil fertility and taro productivity. When no N and P fertiliser was applied, average fresh taro corm yields were very low (6.2 t/ha), irrespective of K and sulphur (S) fertiliser inputs. The addition of up to 200 kg N/ha and 120 kg P/ha, resulted in a substantial average yield increase to 14.9 t/ha. Taro yields were also responsive to K fertiliser use, with significant increases in yield up to 200 kg K/ha, the highest rate of K assessed. There was a strong linear relationship between N fertiliser use and taro sucker population up to 300 kg N/ha. In the second experiment, sucker numbers increased with increasing N fertiliser rate up to 280 kg N/ha. Further increasing N rates up to 360 kg N/ha did no further increase sucker production. When no fertiliser was applied, average taro sucker population across the three sites was about 20,500 suckers/ha, which increased to about 122,500/ha at 280 kg N/ha. The response of sucker numbers to N was not influenced by P fertiliser use, but there was a small effect with increasing K fertiliser rate, from 100 to 200 kg K/ha. Following natural disasters, when sucker numbers are limited, the use of N fertiliser may be an effective short-term strategy to help re-establish the taro industry and minimise inflated sucker prices. The use of the legume mucuna, as a green manure crop intercropped with taro, reduced N fertiliser requirements. Mucuna provided a benefit, for both corm yield and sucker numbers, equivalent to N fertiliser applied at a rate of approximately 80-100 kg N/ha. Some of the benefit may also be due to improved weed suppression and a mulching effect from mucuna. Mixing P fertiliser in the planting hole increased corm yields by 38%, compared to the when P fertiliser was placed at the bottom of the hole. Despite the high rates of P fertiliser used in the first experiment there were no significant P carry-over effects on taro yields in the second experiment. This was due to the higher soil P status from P fertiliser application being confined in close proximity to the planting holes. The Soil Plant Analysis Development (SPAD) chlorophyll meter was evaluated as being effective at predicting N status of taro crops and yield potential, when other major nutrients were non-limiting. When SPAD readings were greater than 65, at 8 and 12 weeks after planting (WAP), then the taro yields were mostly high (i.e. > 12 t/ha). SPAD readings less than 40, at 8 and 12 WAP, would indicate that plant N status is likely to limit taro yield and that a review of N fertiliser use is required. The recommended nutrient management strategy for taro farmers with farms with degraded soil fertility, involves the use of inter-cropping taro with a mucuna green manure crop in combination with fertiliser at the following nutrient rates; 120 kg N, 120 kg, 200 kg K/ha and 80 kg S/ha. At current taro corm and sucker prices, this recommended strategy is expected to provide a net income of NZ$35,835, which is 247% higher than for the average grower practice. The recommended practice also produces 74% more taro suckers than the current grower practice. Increasing sucker production is an important strategy to enable taro growers to increase production quickly following a natural disaster, helping farmers be more resilient to the effects of Climate Change.
  • Thumbnail Image
    Item
    Review of the potential for harmonisation of sustainable food system indicators, and the assessment of key aspects of nutrition and health in two atoll Islands of Kiribati, a West Pacific Island State : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Wellington, New Zealand
    (Massey University, 2019) Eme, Paul Eze
    Sustainable diets, which links nutrition and food systems, cuts across all seventeen Sustainable Development Goals (SDG), with particular relevance to SDG 2. Despite much recent attention being given to sustainable diets and food systems, methodologies for assessing sustainable diets are complex and may not be generally applicable. This thesis describes a series of studies, which aimed to review the methodologies for assessing sustainable diets and potential for development of a harmonized indicators; assess the knowledge, attitude and practice (KAP) on nutrition of the households in South Tarawa and Butaritari Islands; conduct dietary assessments amongst the household members using a 24-h diet recall and weighed food records methodology in the Islands; and carry out anthropometric and body adiposity measurements of the householders and secondary school students. A total 468 households were randomly selected in South Tarawa (n=161) and Butaritari (n=307) for the 24-h dietary recall and a sub-sample of 28 households participated in the weighed food record. Another 320 subjects were recruited for the KAP study on nutrition; and 483 adults and 194 adolescents were selected for the anthropometric and body adiposity study respectively. Food consumption patterns of the households in the islands reflected high consumption of non-traditional diets and refined foods, which manifested in inadequate micronutrient intake estimates and low dietary diversity The KAP study showed the majority of respondents had good knowledge and attitudes towards good nutrition, however, these were not adequately reflected in their nutritional practices. Based on measures of bioelectric impedance, two-thirds of the subjects (68.4%) had a very high body fat (BF) %, 22.2% had high BF%, 8.8% had normal BF% and 0.6% had low BF%. Based on body mass index (BMI), about three-quarters of the subjects (73.2%) were obese and 22.5% were overweight. Obesity prevalence among the adolescents was low based on BMI and BF% criteria. In conclusion, despite the investments on nutrition programmes in Kiribati, no change was noticed from the results of 1985 Kiribati National Nutrition Survey and the findings of this study. Policies and interventions to sustainably improve diets in Kiribati, and thus reduce diet-related morbidity and mortality, need to address elements of sustainable diets.