is a journal of the Tea Research Institute. It is published twice annually, in July and December, by the Tea Research Institute (TRI), P.O. Box 820-20200 Kericho, Kenya, e-mail:websit
The Tea Research Institute does not necessarily agree with, nor take responsibility for information contained in articles submitted by contributors other than the Institute's.
Not to be reproduced in part or whole without the permission of the Institute Director, Tea Research Institute.
Instructions to authors are given at the last page of this issue.
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Tea 35(1) 2014, 1-2
WEATHER AND TEA YIELDS
By B.C. Cheserek
Weather during the period January to June, 2014
of Rift Valley generally had increased
was varied and different from the long-term
production with a mean positive variance of
pattern (see summary in Table 3) especially the
6.98%. However, only Embu and Tharaka-Nithi
rainfall distribution. The period was generally
Counties in the east of Rift valley had negative
drier (886mm) as compared to the long-term
variance, while Meru County had the highest
positive variance of 13.4% in all tea growing
(1132mm). The months of January, February
counties during the period. In the west of Rift,
and April recorded much lower rainfall than the
Kericho County recorded the highest negative
long-term average of these months (Table 3).
variance of -13.5% followed by Bomet County
Estimated cumulative potential soil water deficit
(-5.44%), while Trans-Nzoia County had the
of 224.6mm in the months of January, February
highest positive variance of 8.98%. This
and April was recorded. The soil moisture
decrease in Kericho and Bomet Counties is
deficits recorded during the month of April was
partially attributed to uprooting and replanting
an unusual occurrence. Such deficits subject tea
programme in the large scale farms in these
plants to moisture stress. Although there was
counties. Twenty four hail incidences with an
one frost occurrence at Changoi, in the
accompanying loss of 146,392.4 kg made tea
beginning of the year, soil moisture stress
were reported from west of Rift compared to 28
caused a drastic decrease in tea production in
incidences reported the previous year with a loss
over 46% the tea growing Counties with a mean
of 985,751kg made tea (Table 2). Hail
negative variance of -0.19% compared to a
incidences were highest in April and June.
positive variance of 42.7% during the same
Nandi region recorded the highest number of
period last year (Table 1). The counties in east
hail incidences during the period.
Tea 35(1) 2014, 3-7
ARMILLARIA ROOT ROT (Armillaria mellea) OF TEA: BIOLOGY, PATHOGENICITY,
SYMPTOMS AND CONTROL
By Hillary Cheruiyot
root rot causes high mortality and yield losses of tree crops globally.
It survives in soils, dead
or dying wood stumps or plant roots for decades as rhizomorphs or mycelium. The fungus is the most
challenging production factor in tea growing areas. It causes up to 50% annual yield losses in Kenya. The
species A. heimii
and A. mellea
are the most common in Africa.
Amount of inoculum and the proximity to
the tea plant determines plant damage. Quantification of inoculum is important in understanding the
spread and pathogenicity of Armillaria.
Inoculum contact is the main mode of spread among tea bushes.
Predisposing factors include drought, insect attack or other diseases. Longitudinal cracks at the collar
region, resin exudation and sheets of creamy white mycelia inside the bark with mushroom like-smell are
distinguishing characteristics. Cultural practices are the best control methods. Eradication of the fungi by
ring barking of trees during land preparation and uprooting diseased bushes enhances control. Biological
management using Trichoderma
antagonist, inhibits mycelial and rhizomorphal growth
thus controlling Armillaria.
Tea 35(1) 2014, 8-16
GENOTYPIC STABILITY AND ADAPTABILITY OF TEA CULTIVARS IN RELATION TO
CATECHIN LEVELS ACROSS FOUR ENVIRONMENTS
By Leonida Cherotich1, Samson M. Kamunya, Amos Alakonya1, Solomon W. Msomba2, Marie A.
Uwimana3 and P.O Owour4
1Institute of Biotechnology Research (IBR), Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200,
City Square, Nairobi, Kenya
2Crop improvement Tea Research Institute of Tanzania, P.O. Box 2177, Dar Es Salaam, Tanzania.
3Office Des Cultures Industrielles du Rwanda The' (OCIR The'), P.O. Box 1344, Kigali, Rwanda
4Department of Chemistry, Maseno University, Private Ba, Maseno, Kenya
In East Africa, tea-growing areas fall in several agro-ecological regions, which differ widely in elevation
and climatic factors, but with favorable soil conditions. Therefore, understanding the effect of interaction
between genotype and environment on catechin content and clonal adaptability is a prerequisite for
successful adoption of diverse and improved cultivars. A study was carried out to determine genetic
stability and adaptability based on catechin levels of 20 improved clones across four distinct
environments. The trial established in two distinct sites in Kenya, in randomized complete block design
with three replicates, and consisted of 10 popular cultivars widely cultivated in the Lake Victoria Basin
and additional 10 newly improved clones. Tea quality data entailing extraction and quantification of
catechins, caffeine and total polyphenols was generated for the 20 clones being evaluated. Genetic
stability and adaptability among the 20 clones under study varied significantly (P<0.001) across
environments. Clone TRFK 31/11 and BBK35 were the most adaptable and stable with a b>1. On the
other hand, clone TRFK371/3 and TRFK 7/3 could be exploited in marginalized environments. A survey
however, needs to be undertaken to determine the suitability of any site for tea cultivation, well ahead of
tea planting. Where possible the study should indicate if a poor environment could be improved to allow
for tea cultivation if cost effectiveness of such venture is demonstrated.
Tea 35(1) 2014, 17-23
EFFECT OF HOMO BRASSINOLIDES ON LEAF GAS EXCHANGE IN CLONAL TEA
By W. K. Ng'etich1 and J. K. Bore
1University of Eldoret, P. O. Box 1125, Eldoret
An experiment was conducted to assess the effects of exogenously applied brassinolides
on tea. The
results showed that stomatal conductance decreased linearly (P≤0.05) with rates of applied growth
regulator. The decrease involved temperature regulation during a period of water stress in that there
was a linear decrease in leaf temperature with increase in rate of applied Bountee. Net assimilation
rate varied linearly with applied Bountee. There was no effect on leaf gas exchange when water was
not limiting. Specific leaf mass increased linearly with applied Bountee. Leaf colour as measured with
Norsk Hydro leaf colour tester showed a gradual increase with increase in applied Bountee. Tea yields
however, were not significantly (P≤0.05) affected by rates of Bountee, but significant differences
occurred during a period of water stress.
Tea 35(1) 2014, 24-32
GAMMA IRRADIATION INDUCES CHANGES IN BIOCHEMICAL PROPERTIES OF TEA
By Kamau, P., Maritim, T., Chalo, R., Kamunya, S. and Wanyoko J.
Induced mutations have effectively increased genetic variability and availability of novel commercial
varieties in cultivated crops. Seeds of 3 commercial tea clones, TRFK 301/5, TRFK 303/577 and GW
Ejulu-L, were treated with 150 Gy gamma irradiation and the resultant mutants coded St. 1003, St.
1004 and St. 1005, respectively and examined for black tea quality parameters. Gamma irradiation
had significant effects (P≤0.05) on all quality parameters studied namely garlic acid (GA),
epigallocatechin (EGC), catechin (+C), epicatechin (EC), epigallocatechin gallate (EGCG) and
epicatechin gallate (ECG) and total catechins (TC). Compared to their parental clones, most progenies
of clone GW Ejulu-L registered significantly higher (P≤0.05) EGCG content, whereas clones 1004/7
and 1005/10 showed high TC content, an indication of potential to select high black tea quality
varieties among the mutants. Further, over 230% higher catechins was recorded among progenies of
TRFK 303/577 (St 1004) as compared to the parental clone. Most notably, all test clones had lower
caffeine levels as compared to their parents indicating potential to select low caffeine teas. A
significant variation in total polyphenols (TP) content was observed with most of the irradiated
progenies outperformed their parental clones. The study alludes gamma irradiation to be an effective
method of inducing biochemical variations in tea with marked possibility of giving rise to novel tea
cultivars for diversified tea products.
Tea 35(1) 2014, 33-43
INHERITANCE OF CATECHIN AND CAFFEINE IN TEA (Camellia sinensis (L.) O. Kuntze)
By Nelson M. Lubang'a1, Samson M. Kamunya, Oliver Kiplagat1, John K. Wanyoko, Richard M. Chalo
1University of Eldoret, P.O. Box 1125, 30100, Eldoret, Kenya.
Diallele designs are used in many breeding programmes because of the important genetic information
they offer to plant breeders. Eight biochemical traits of tea (Camellia sinensis
(L.) O. Kuntze) were
studied to investigate the underlying gene action, and estimate the general combining abilities (GCA) and
specific combining abilities (SCA) of parents and crosses using diallele mating system. There were
significant (P<0.05) differences among the genotypes for all the traits under study. The general
combining ability (GCA) effects were significant for six of the traits, namely GA, EGC, Caffeine, ECG,
EGCG and total catechin implying that these traits are governed by additive gene effects. SCA on the
other hand was significant for EGC, Caffeine, EC, EGCG, and total catechin. Maternal effects were
significant for EGC, EGCG and total catechin signifying importance of the choice of female parents in
breeding programmes targeting these traits. Non-maternal effects were present in EGCG and total
catechin. The study revealed that parents which would produce above average progenies for total
catechins are AHP S15/10 and EPK TN14-3. The best combiners for total catechins were EPK TN14-3 x
TRFK 6/8 and AHP S15/10 self. This information, which has hitherto been lacking will be very valuable
for tea breeding programmes targeting high black/green tea qualities.
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