Abstract
SUMMARY The physiological basis for differences in yields from well-watered and draughted plants of four contrasting clones of tea was studied in terms of light interception, dry matter production and partitioning at a high altitude site in Southern Tanzania where there are marked seasonal variations in rainfall and temperature. The plant dry weights, including roots, were measured eight months after field planting and subsequently at intervals of three to four months, corresponding to the different seasons, during the following two years. Fully irrigated plants of one clone (S15/10) were also harvested after four years in the field. Clones differed in the rates of canopy spread and hence in their capacity to intercept solar radiation. The ‘radiation use efficiency’ (the net total dry matter production per unit of intercepted short-wave radiation) was similar for the four well-watered clones and ranged from 0.40 to 0.66 g MJ −1 , which corresponds closely to values reported for other woody tropical plants. A 16-week drought treatment imposed two years after planting reduced the mean light interception of the four clones by about 25% and the mean radiation use efficiency by 78% to 0.09 g MJ −1 . Clone S15/10, a cultivar from Kenya which produces large yields, partitioned a greater proportion of dry matter to leaves and harvested shoots than the other clones, and correspondingly less to large structural roots. This resulted in a maximum harvest index of 24%, substantially greater than other values reported in the literature. There were seasonal differences in partitioning, with more dry matter being diverted to roots and less to shoots during the cool season. Although the drought treatments had no significant effect on root growth, the amount of dry matter partitioned to leaves, stems and harvested shoots declined by 80–95%. The roots of all four clones extended in depth at similar rates (about 2 mm d −1 ), those of Clone S15/10 reaching 2.8m after four years. The results are discussed in terms of appropriate field cultural practices and possible selection criteria for high yielding clones.
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Claims 12
Claim · model-written summary
Tea clones differed in their rates of canopy spread and so in capacity to intercept solar radiation.
- Taxon
- Camellia sinensis
Camellia sinensist0 - Outcome
- rates of canopy spreade1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Young Tea (Camellia sinensis) Clones”
e1“Clones differed in the rates of canopy spread and hence in their capacity to intercept solar radiation”
Claim · model-written summary
Radiation use efficiency was similar across the four well-watered tea clones, at 0.40 to 0.66 g MJ -1.
- Taxon
- Camellia sinensisCamellia sinensist0
- Outcome
- radiation use efficiencye2
- Direction
- no_changeinferrede2
- Value
- 0.40 to 0.66 g MJ −1e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Young Tea (Camellia sinensis) Clones”
e2“The ‘radiation use efficiency’ (the net total dry matter production per unit of intercepted short-wave radiation) was similar for the four well-watered clones and ranged from 0.40 to 0.66 g MJ −1”
Claim · model-written summary
A 16-week drought reduced mean light interception of the four clones by about 25%.
- Taxon
- Camellia sinensisCamellia sinensist0
- Treatment
- 16-week drought treatmente3
- Outcome
- mean light interceptione3
- Direction
- reducede3
- Value
- about 25%e3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Young Tea (Camellia sinensis) Clones”
e3“A 16-week drought treatment imposed two years after planting reduced the mean light interception of the four clones by about 25% and the mean radiation use efficiency by 78% to 0.09 g MJ −1”
Claim · model-written summary
A 16-week drought reduced mean radiation use efficiency by 78%, to 0.09 g MJ -1.
- Taxon
- Camellia sinensisCamellia sinensist0
- Treatment
- 16-week drought treatmente3
- Outcome
- mean radiation use efficiencye3
- Direction
- reducede3
- Value
- 78%e3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Young Tea (Camellia sinensis) Clones”
e3“A 16-week drought treatment imposed two years after planting reduced the mean light interception of the four clones by about 25% and the mean radiation use efficiency by 78% to 0.09 g MJ −1”
Claim · model-written summary
Clone S15/10 partitioned a greater proportion of dry matter to leaves and harvested shoots than the other clones.
- Taxon
- Camellia sinensisCamellia sinensist0
- Material
- Clone S15/10e5
- Outcome
- proportion of dry mattere5
- Direction
- greatere5
- Comparator
- the other clonese5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Young Tea (Camellia sinensis) Clones”
e5“Clone S15/10, a cultivar from Kenya which produces large yields, partitioned a greater proportion of dry matter to leaves and harvested shoots than the other clones, and correspondingly less to large structural roots”
Claim · model-written summary
Clone S15/10 partitioned less dry matter to large structural roots than the other clones.
- Taxon
- Camellia sinensisCamellia sinensist0
- Material
- Clone S15/10e5
- Outcome
- large structural rootse5
- Direction
- lesse5
- Comparator
- the other clonese5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Young Tea (Camellia sinensis) Clones”
e5“Clone S15/10, a cultivar from Kenya which produces large yields, partitioned a greater proportion of dry matter to leaves and harvested shoots than the other clones, and correspondingly less to large structural roots”
Claim · model-written summary
Clone S15/10 reached a maximum harvest index of 24%, substantially greater than values reported in the literature.
- Taxon
- Camellia sinensisCamellia sinensist0
- Outcome
- harvest indexe7
- Direction
- greatere7
- Value
- 24%e7
- Comparator
- other values reported in the literaturee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Young Tea (Camellia sinensis) Clones”
e7“This resulted in a maximum harvest index of 24%, substantially greater than other values reported in the literature”
Claim · model-written summary
Dry matter was diverted more to roots and less to shoots during the cool season.
- Taxon
- Camellia sinensisCamellia sinensist0
- Organ / stage
- rootse1
- Outcome
- dry matter being diverted to rootse1
- Direction
- moree1
- Qualifier
- less to shootse1
- Setting
- cool seasone1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Young Tea (Camellia sinensis) Clones”
e1“There were seasonal differences in partitioning, with more dry matter being diverted to roots and less to shoots during the cool season”
Claim · model-written summary
The drought treatments had no significant effect on root growth.
- Taxon
- Camellia sinensisCamellia sinensist0
- Treatment
- drought treatmentse2
- Outcome
- root growthe2
- Direction
- no_changeinferrede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Young Tea (Camellia sinensis) Clones”
e2“Although the drought treatments had no significant effect on root growth, the amount of dry matter partitioned to leaves, stems and harvested shoots declined by 80–95%”
Claim · model-written summary
Drought declined the amount of dry matter partitioned to leaves, stems and harvested shoots by 80–95%.
- Taxon
- Camellia sinensisCamellia sinensist0
- Treatment
- drought treatmentse2
- Outcome
- the amount of dry matter partitioned to leaves, stems and harvested shootse2
- Direction
- declinede2
- Value
- 80–95%e2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Young Tea (Camellia sinensis) Clones”
e2“Although the drought treatments had no significant effect on root growth, the amount of dry matter partitioned to leaves, stems and harvested shoots declined by 80–95%”
Claim · model-written summary
Roots of all four tea clones extended in depth at similar rates, about 2 mm d -1.
- Taxon
- Camellia sinensisCamellia sinensist0
- Organ / stage
- rootse4
- Outcome
- extended in depthe4
- Direction
- no_changeinferrede4
- Value
- about 2 mm d −1e4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Young Tea (Camellia sinensis) Clones”
e4“The roots of all four clones extended in depth at similar rates (about 2 mm d −1), those of Clone S15/10 reaching 2.8m after four years”
Claim · model-written summary
Roots of Clone S15/10 reached 2.8 m depth after four years.
- Taxon
- Camellia sinensisCamellia sinensist0
- Material
- Clone S15/10e4
- Organ / stage
- rootse4
- Outcome
- extended in depthe4
- Value
- 2.8me4
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Young Tea (Camellia sinensis) Clones”
e4“The roots of all four clones extended in depth at similar rates (about 2 mm d −1), those of Clone S15/10 reaching 2.8m after four years”
The same questions in other papers
drought · growth · Camellia sinensis (black tea)Results agree
6 papers in the same direction as this paper
- no effect
- negative
- negative
3 papers more in this group
See all 7 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.