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Accueil du site → Doctorat → Afrique du Sud → 2022 → Potato (Solanum tuberosum L.) production in a changing climate : analysis of responses to elevated temperature and moisture conditions

University of South Africa (2022)

Potato (Solanum tuberosum L.) production in a changing climate : analysis of responses to elevated temperature and moisture conditions

Mdlalose, Samukelisiwe Precious

Titre : Potato (Solanum tuberosum L.) production in a changing climate : analysis of responses to elevated temperature and moisture conditions

Auteur : Mdlalose, Samukelisiwe Precious

Université de soutenance : University of South Africa

Grade : Doctor of Philosophy Ph D. (Agriculture) 2022

Résumé partiel
This study was undertaken to investigate the effects of increasing atmospheric temperature, combined with either drought or flooding, on the growth, development and productivity of the Markies and Fianna potato cultivars. Furthermore, the effects of abiotic stress on the metabolomic profile of these two potato cultivars were studied and a comparison of their quality, growth and yield was drawn. These two potato cultivars (i.e. Markies and Fianna) were planted over three growing seasons. The first experiment (2016) was a preliminary study, undertaken to evaluate the methodology to be used for research on the effects of environmental stresses brought by climatic changes (that is, drought, flooding and increasing temperature) on potato growth and development. During this experimentation year (2016) growth chambers were used to control temperature on three levels : Growth chamber 1 (24°C), Growth chamber 2 (25°C) and Growth chamber 3 (27°C). Due to the size constraint of growth chambers, only 32 plants could be planted. The other two growing seasons (2017 and 2018), each experiment consisted of 108 potatoes planted (total 216 plants) and were exposed to three different water treatments, i.e. normal (control), flooding and drought ; administered using portable water in a completely randomised block design in the greenhouse. In total, 98 metabolites were detected through LC-MS from the potato leaves. In addition, representative tubers of the treated plants were collected 91 days after planting. The tuber samples were freeze-dried, and ground to a fine powder in liquid nitrogen. The fine powder of the tuber samples was analysed by nuclear magnetic resonance spectroscopy (NMR) to identify their metabolomic profiles. The NMR data was analysed using principal component analysis and orthogonal partial least square discriminant analysis to identify any variations between the treatments. In both models, plants exposed to drought clearly separated from the plants that received either excess or moderate water. The potato tubers that experienced drought and flood treatments had the highest quantities of aspartic acid, asparagine, and isoleucine. The treatments resulted in varied quantities of metabolite production in both cultivars. Plants defense metabolites, such as phenylalanine, 2-aminobutyric, amino acids, valine, isoleucine and leucine were increased in the drought and flood experiments, supporting the notion that abiotic stress can result in strong expression of compounds such as these, as a tolerance mechanism

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