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Systematic Review ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Plant Sci. | doi: 10.3389/fpls.2019.00939

Environmental Factors Variably Impact Tea Secondary Metabolites in the Context of Climate Change: A Systematic Review

 Selena Ahmed1*,  Timothy Griffin2,  Debra Kraner1,  Katherine Schaffner2, Deepak Sharma1*, Deepak Sharma2, Alicia Leitch1,  Colin M. Orians3,  Wenyan Han4, John R. Stepp5, Albert Robbat3,  Corene Matyas5,  Long Chunlin6, Xue Dayuan6, Robert Houser2 and  Sean Cash2
  • 1Montana State University, United States
  • 2Tufts University School of Nutrition Science and Policy, United States
  • 3Tufts University, United States
  • 4Tea Research Institute, Chinese Academy of Agricultural Sciences, China
  • 5University of Florida, United States
  • 6Minzu University of China, China

Climate change is impacting food and beverage crops around the world with implications for environmental and human wellbeing. While numerous studies have examined climate change effects on crop yields, relatively few studies have examined effects on crop quality (concentrations of nutrients, minerals, and secondary metabolites). This review article employs a culturally relevant beverage crop, tea (Camelia sinensis), as a lens to examine environmental effects linked to climate change on the directionality of crop quality. Our systematic review identified eighty-six articles as relevant to the review question. Findings provide evidence that shifts in seasonality, water stress, geography, light factors, altitude, herbivory and microbes, temperature, and soil factors that are linked to climate change can result in both increases and decreases up to 50% in secondary metabolites. A gap was found regarding evidence on the direct effects of carbon dioxide on tea quality, highlighting a critical research area for future study. While this systematic review provides evidence that multiple environmental parameters are impacting tea quality, the directionality and magnitude of these impacts is not clear with contradictory evidence between studies likely due to confounding factors including variation in tea variety, cultivar, specific environmental and agricultural management conditions, and differences in research methods. The environmental factors with the most consistent evidence in this systematic review were seasonality and water stress with 14 out of 18 studies (78%) demonstrating a decrease in concentrations of phenolic compounds or their bioactivity with a seasonal shift from the spring and /or first tea harvest to other seasons and seven out of ten studies (70%) showing an increase in levels of phenolic compounds or their bioactivity with drought stress. Herbivory and soil fertility were two of the variables that showed the greatest contradictory evidence on tea quality. Both herbivory and soil fertility are variables which farmers have the greatest control over, pointing to the importance of agricultural management for climate mitigation and adaptation. The development of evidence-based management strategies and crop breeding programs for resilient cultivars are called for to mitigate climate impacts on crop quality and overall risk in agricultural and food systems.

Keywords: Climate Change, crop quality, secondary metabolites, Agriculture, food systems

Received: 11 Mar 2019; Accepted: 04 Jul 2019.

Edited by:

Jens Rohloff, Norwegian University of Science and Technology, Norway

Reviewed by:

Carsten Kulheim, Michigan Technological University, United States
Derek Stewart, The James Hutton Institute, United Kingdom  

Copyright: © 2019 Ahmed, Griffin, Kraner, Schaffner, Sharma, Sharma, Leitch, Orians, Han, Stepp, Robbat, Matyas, Chunlin, Dayuan, Houser and Cash. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Prof. Selena Ahmed, Montana State University, Bozeman, United States, selena.ahmed@montana.edu
Mr. Deepak Sharma, Montana State University, Bozeman, United States, dsharma.ce@gmail.com