Effect of temperature on plant growth and stress tolerant traits in rooibos in the Western Cape, South Africa

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  • Dunja MacAlister
  • ,
  • A. Muthama Muasya, University of Cape Town, Univ Cape Town, University of Cape Town, Dept Biol Sci
  • ,
  • Olivier Crespo, University of Cape Town
  • ,
  • John B.O. Ogola, University of Venda
  • ,
  • Sipho Maseko, Tshwane University of Technology
  • ,
  • Alex J. Valentine, Stellenbosch University
  • ,
  • Carl-Otto Ottosen
  • Eva Rosenqvist, University of Copenhagen, Denmark
  • Samson B.M. Chimphango, University of Cape Town

Mediterranean systems, such as in South Africa, are particularly vulnerable to the predicted increases in mean surface temperatures which will likely affect the growth and physiology of many plants and subsequently affect agricultural productivity. Aspalathus linearis (Burm.f.) R. Dahlgren (rooibos) is an important commercial, endemic crop that is produced in the Cederberg region, South Africa. This region experiences a Mediterranean-type ecosystem that is characterised by hot, dry summers (November – February) and cool, wet winters (May – August). This study assessed the effects of temperature on the growth and stress tolerant traits of A. linearis over two years. Crop biomass and selected physiological traits were determined in the field, along a temperature gradient, at four farm sites in the Cederberg during the summer and winter 2017 and summer 2018. Aspalathus linearis plants showed evidence of transpirational leaf cooling during summer and this, combined with lower chlorophyll and high phenolic content, could be considered acclimatized adaptive changes allowing the plants to mitigate the heating effects of elevated temperatures. Although changes in soil nutrients and increasing temperatures had a negative impact on crop biomass, the phenolic content, a measure of tea quality, did not vary with sites. This suggests that a shift in rooibos farming to cooler and wetter areas further south, for better growth and higher yields, would not compromise the quality of rooibos tea.

Original languageEnglish
Article number109137
JournalScientia Horticulturae
Volume263
Number of pages14
ISSN0304-4238
DOIs
Publication statusPublished - 2020

    Research areas

  • Aspalathus linearis, Climate change, Leaf cooling, Thermotolerance

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