Environmental Factors Variably Impact Tea Secondary Metabolites in the Context of Climate Change

Abstract

Climate change is impacting food and beverage crops around the world with implications for environmental and human well-being. 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 86 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 10 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.

Emerging Advanced Technologies to Mitigate the Impact of Climate Change in Africa

“…A population of such magnitude requires an assured and steady supply of basic food that guarantees socioeconomic stability across the world. This means, to meet food demands of this growing population, crop yield has to double in the next 30 years, representing an annual yield increase of 2.2% [3,6]. Currently, development and global distribution of natural and synthetically generated fertilisers (particularly nitrogen, phosphorus and potassium), coupled with the green revolution, which has encouraged utilization of non-traditional breeding methods to maximise plant architecture and light harvesting, have increased production of a number of staple foods.…”

“…West Africa, for instance, has been identified as a climate-change hotspot, with climate change likely to lessen crop yields and production, with resultant impacts on food security. Reductions of 20% and 32% in maize production as a result of climate change have been projected [6][7][8]. The high impact of the effects of climate change in Africa have been attributed to its geographical position and limited adaptive capacity [9], exacerbated by widespread poverty and low levels of development.…”

Is Agricultural Emissions Mitigation on the Menu for Tea Drinkers?

“…Consumers were required to taste both the pre-monsoon and monsoon harvested samples because a concurrent study was assessing the sensory characteristics and consumer WTP for tea harvested in different seasons. In addition, feedback from the focus groups and prior research indicates that harvest season is especially important to the quality and flavor of green teas [49][50][51]. A detailed explanation of the tea tasting protocol can be found in the Supplementary Materials.…”

Physiological and Defense Responses of Tea Plants to Elevated CO2: A Review

“…The concentration of atmospheric CO 2 is still increasing, and it will possibly reach 800 ppm by the end of the 21st century (IPCC, 2014). It is inferred that with increasing CO 2 , the adversities of extreme climate events such as heatwave, drought, and frost will be increasing, which will variously affect tea yield, quality and ecosystem (Li et al, 2018(Li et al, , 2019aAhmed et al, 2019). Nonetheless, tea plantations play a significant role in CO 2 sequestration and thus tea gardens can be useful in mitigating global warming (Pramanik and Phukan, 2020).…”

“…Although the effects of climate change on the yield of food crops have extensively been studied, its impact on tea has received less attention. In particular, research on the effect of elevated CO 2 on tea is still in its infancy (Ahmed et al, 2019). However, recently more attention has been paid to the issue and inter-governmental initiatives have been taken to address climate change effects on tea under the umbrella of the Food and Agriculture Organization of the United Nations (Han et al, 2018).…”