Postgraduate Profiles

David Minemba

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Thesis: Understanding the sweet potato rhizosphere under Phosphorous stressed soils

The storage root (or tuber) yield of sweet potato plant range between 3-50 t/ha under different growing conditions or even within cultivars in same plots. These wide yield variations occur as plants are exposed to different stress factors, both biotic and abiotic. While many studies have been conducted to find solutions to most known stress issues, no specific work focused on understanding the role of root exudates of sweet potato plant and the chemical and biological process that occur in its rhizosphere. The chemical compounds of root exudates and the microorganisms in the soil rhizosphere basically alter soil chemistry and the biological processes. This biological activity in the rhizosphere assist the plant to cope with most stressful conditions. Therefore the objective of this PhD study is to determine for sweet potato the specific root exudates secreted under Phosphorus stress conditions and the dominant microbial population in the rhizosphere.

Why my research is important

Sweet potato is mostly grown for its starchy storage root, which is not only used as an important food source, but also serves as raw material for industrial purposes such as starch and alcohol production. It is grown extensively in the tropics and warm temperate regions in the world from 40o N to 40o S of the equator and from sea level to 2800 meters in altitude. Sweet potato is a dominant staple crop in Papua New Guinea, (06o 00 S, 147o 00 E). An estimate of 3 million tonnes is grown annually for local consumption. The outcomes from this study will provide useful understanding on the coping ability of sweet potato in most P impoverished soils that exist in PNG and elsewhere.


Jun 2015

Jun 2019