Advances in Phytochemistry, Textile and Renewable Energy Research for
Industrial Growth – Nzila et al. (Eds)
© 2022 Copyright the Author(s), ISBN: 978-1-032-11871-0
Open Access: www.taylorfrancis.com, CC BY-NC-ND 4.0 license
Evaluation of shading on tea yield and phenolics in aerated and unaerated
products
R.K. Korir & S.M. Kamunya
KALRO-Tea Research Institute, Kericho, Rift Valley, Kenya
R.C. Ramkat
Moi University, Eldoret, Rift Valley, Kenya
African Center of Excellence in Phytochemicals, Textiles and Renewable Energy (PTRE)
R.C. Muoki ∗
KALRO-Tea Research Institute, Kericho, Rift Valley, Kenya
ABSTRACT: Varying climatic conditions have pronounced effects on the tea plant. This study was to evaluate
the effects of shade on yield and quality in aerated and unaerated products. Cultivar TRFK 6/8 was maintained
under three shading regimes (30, 60, and 90%) and unshaded control in three seasons of a year.Yield components
included shoot growth, shoot density, and monthly seasonal yields. Biochemical parameters included catechins,
caffeine, and polyphenols. Yield components, catechin, and caffeine were negatively affected while polyphenols
was positively affected by an increase in shading. Product diversification is possible in existing populations
through the production of unaerated tea under moderate shading (30 and 60%) during the cold/wet season and
high-quality aerated product during warm/hot seasons while maintaining optimum yields. There is a need to
undertake genomic studies so as to provide insights into complex regulatory networks and the identification of
genes relevant to biochemical changes due to shading in tea.
1 INTRODUCTION
The tea (Camellia sinensis (L.) O. Kuntze) plant plays
a significant role to the economy of most developing countries cultivating the crop. Tea made from the
leaves of the plant, processed into green or black
tea, is drunk as a mild stimulant due to the caffeine
content, since time in memorial (Tong et al., 2014).
Overproduction of black cut, tear, and curl (BCTC)
tea in Kenya has led to the stagnation/decline in the
unit prices of processed tea despite increased costs
of production, resulting in decreased returns for tea
growers. As the world market for black tea continues
to shrink, that for green tea and other forms of specialty teas is growing. For instance, in the year 2018,
Japan earned 27.27 USD per kilogram made (kg.mt)
for green tea compared to 2.93 USD per kg.mt for
black CTC in Kenya. Japan also produces Matcha; the
highest-quality green tea made from tencha which is
grown under shade and contains a high amino acid content together with a low catechin content. Sweetness
is associated with amino acids, particularly theanine,
which has a taste that is described as “umami” or
∗ Corresponding author
“brothy,” while catechins and caffeine contribute to
the astringency of the liquor (Liu et al., 2017).
Shading has been shown to effectively improve the
quality of tea beverages by causing a reduction of the
concentration of flavonoids, which are the main compounds that contribute to astringency, in the leaves
(Wang et al. 2012). Further, tea plants in their original habitat grow under natural shade. Therefore, the
use of shade trees in tea plantations was adopted to
emulate the natural conditions (Eden, 1976). Shading
is also a cultural practice used to mitigate the effects
of adverse weather conditions. Shade trees in tea plantations are important in the reduction of temperatures,
that ultimately reduces excessive transpiration and
moisture losses. In addition, shading protects the plant
against losses arising from hail damage and frost bite
which is approximated at 2 million kilograms per year
(Figure 1).
The present study was therefore designed to guide
the tea industry to ameliorate the environmental conditions in the existing plantations. This would improve
tea yields and quality for the processing of specialty
and diversified products without necessarily uprooting and replanting, which is a very costly venture for
the resource-constrained smallholder farmers.
176
DOI 10.1201/9781003221968-24
Industrial Growth – Nzila et al. (Eds)
© 2022 Copyright the Author(s), ISBN: 978-1-032-11871-0
Open Access: www.taylorfrancis.com, CC BY-NC-ND 4.0 license
Evaluation of shading on tea yield and phenolics in aerated and unaerated
products
R.K. Korir & S.M. Kamunya
KALRO-Tea Research Institute, Kericho, Rift Valley, Kenya
R.C. Ramkat
Moi University, Eldoret, Rift Valley, Kenya
African Center of Excellence in Phytochemicals, Textiles and Renewable Energy (PTRE)
R.C. Muoki ∗
KALRO-Tea Research Institute, Kericho, Rift Valley, Kenya
ABSTRACT: Varying climatic conditions have pronounced effects on the tea plant. This study was to evaluate
the effects of shade on yield and quality in aerated and unaerated products. Cultivar TRFK 6/8 was maintained
under three shading regimes (30, 60, and 90%) and unshaded control in three seasons of a year.Yield components
included shoot growth, shoot density, and monthly seasonal yields. Biochemical parameters included catechins,
caffeine, and polyphenols. Yield components, catechin, and caffeine were negatively affected while polyphenols
was positively affected by an increase in shading. Product diversification is possible in existing populations
through the production of unaerated tea under moderate shading (30 and 60%) during the cold/wet season and
high-quality aerated product during warm/hot seasons while maintaining optimum yields. There is a need to
undertake genomic studies so as to provide insights into complex regulatory networks and the identification of
genes relevant to biochemical changes due to shading in tea.
1 INTRODUCTION
The tea (Camellia sinensis (L.) O. Kuntze) plant plays
a significant role to the economy of most developing countries cultivating the crop. Tea made from the
leaves of the plant, processed into green or black
tea, is drunk as a mild stimulant due to the caffeine
content, since time in memorial (Tong et al., 2014).
Overproduction of black cut, tear, and curl (BCTC)
tea in Kenya has led to the stagnation/decline in the
unit prices of processed tea despite increased costs
of production, resulting in decreased returns for tea
growers. As the world market for black tea continues
to shrink, that for green tea and other forms of specialty teas is growing. For instance, in the year 2018,
Japan earned 27.27 USD per kilogram made (kg.mt)
for green tea compared to 2.93 USD per kg.mt for
black CTC in Kenya. Japan also produces Matcha; the
highest-quality green tea made from tencha which is
grown under shade and contains a high amino acid content together with a low catechin content. Sweetness
is associated with amino acids, particularly theanine,
which has a taste that is described as “umami” or
∗ Corresponding author
“brothy,” while catechins and caffeine contribute to
the astringency of the liquor (Liu et al., 2017).
Shading has been shown to effectively improve the
quality of tea beverages by causing a reduction of the
concentration of flavonoids, which are the main compounds that contribute to astringency, in the leaves
(Wang et al. 2012). Further, tea plants in their original habitat grow under natural shade. Therefore, the
use of shade trees in tea plantations was adopted to
emulate the natural conditions (Eden, 1976). Shading
is also a cultural practice used to mitigate the effects
of adverse weather conditions. Shade trees in tea plantations are important in the reduction of temperatures,
that ultimately reduces excessive transpiration and
moisture losses. In addition, shading protects the plant
against losses arising from hail damage and frost bite
which is approximated at 2 million kilograms per year
(Figure 1).
The present study was therefore designed to guide
the tea industry to ameliorate the environmental conditions in the existing plantations. This would improve
tea yields and quality for the processing of specialty
and diversified products without necessarily uprooting and replanting, which is a very costly venture for
the resource-constrained smallholder farmers.
176
DOI 10.1201/9781003221968-24