Analysis of Canopy Photosynthesis in Mature Tea(Camellia sinensis L.) Bush at Late Autumn.

Kano, Kunio; Komaki, Shinya; Matsuo, Kiyoshi; Hirose, Daisuke; Tatsumi, Jiro

doi:10.1626/jcs.64.310

Cited by 17 publications

(6 citation statements)

References 7 publications

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“…In agreement with the findings of Okano et al (1995Okano et al ( , 1996, De Costa et al (unpublished results) also found that the top two layers (i.e. 0-10 cm and 10-20 cm canopy depths) contributed 80-90% of P g (Figures 2A and 3A).…”

Section: Co 2 Concentrationsupporting

confidence: 88%

“…There is considerable variation in the reported saturating light intensities, ranging from 600-800 µmol (PAR) m -2 s -1 (Sakai, 1975;Squire, 1977;Gee et al, 1982;Mohotti, 2004) through 1000 µmol m -2 s -1 of PAR (Sakai, 1987;Smith et al, 1993aSmith et al, , 1994 up to 1200-1500 µmol m -2 s -1 ) (Okano et al, 1995). This indicates probable genotype x environment interaction effects.…”

Section: Photosynthesismentioning

confidence: 99%

“…Therefore, distribution of incident radiation within the canopy through light penetration along with P n as determined by the internal and external factors discussed above determine the magnitude of P c . Using 13 CO 2 , Okano et al (1995) showed that 85% of P c of tea growing in autumn in Japan was carried out by the top 5 cm leaf layer of the canopy and that the maximum canopy depth effective for photosynthesis was only 10 cm. However, Okano et al (1996) concluded that in spring, at the plucking stage, nearly 90% of P c was conducted by developing new leaves and the contribution by overwintering mature leaves was only 10%.…”

Section: Co 2 Concentrationmentioning

confidence: 99%

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Ecophysiology of tea

Costa

Mohotti

Wijeratne

2007

Braz. J. Plant Physiol.

118

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Tea [Camellia sinensis (L.) O. Kuntze] is one of the most important beverage crops in the world. The major tea-growing regions of the world are South-East Asia and Eastern Africa where it is grown across a wide range of altitudes up to 2200 m a.s.l.. This paper reviews the key physiological processes responsible for yield determination of tea and discusses how these processes are influenced by genotypic and environmental factors. Yield formation of tea is discussed in terms of assimilate supply through photosynthesis and formation of harvestable sinks (i.e. shoots). The photosynthetic apparatus and partial processes (i.e. light capture, electron transport and carboxylation) of tea show specific adaptations to shade. Consequently, maximum light-saturated photosynthetic rates of tea are below the average for C 3 plants and photoinhibition occurs at high light intensities. These processes restrict the source capacity of tea. Tea yields are sink-limited as well because shoots are harvested before their maximum biomass is reached in order to maintain quality characters of made tea. In the absence of water deficits, rates of shoot initiation and extension are determined by air temperature and saturation vapour pressure deficit, with the former having positive and the latter having negative relationships with the above rates. During dry periods, when the soil water deficit exceeds a genotypically-and environmentally-determined threshold, rates of shoot initiation and extension are reduced with decreasing shoot water potential. Tea yields respond significantly to irrigation, a promising option to increase productivity during dry periods, which are experienced in many tea-growing regions. Key words: climate change, photoinhibition, photosynthesis, shoot growth, temperature, vapour pressure deficit, water potential † All authors have contributed equally to this articleEcofisiologia do chá: O chá [Camellia sinensis (L.) O. Kuntze] é uma das mais importantes culturas para a produção de bebidas no mundo. As principais regiões de cultivo dessa espécie se concentram no sudeste da Ásia e na África oriental, onde é cultivado numa ampla faixa de altitudes, até 2200 m acima do nível do mar. Neste artigo, revisam-se processos fisiológicos centrais determinantes da produção do chá e se discutem como esses processos são influenciados por fatores genotípicos e ambientes. A produção do chá é discutida em termos de suprimento de assimilados provenientes da fotossíntese e formação de drenos (ramos) removidos na colheita. A maquinaria fotossintética e processos parciais (i.e. captura de luz, transporte de elétrons e carboxilação) da fotossíntese, em plantas de chá, exibem adaptações à sombra. Conseqüentemente, as taxas máximas de fotossíntese saturadas à luz são inferiores às da media de plantas C 3 , observando-se também fotoinibição sob altas irradiâncias. Esses processos restringem a capacidade da fonte em plantas de chá. A produção do chá é limitada pelo dreno conquanto os ramos são colhidos antes de atingirem sua biomassa máxima, o q...

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Section: Co 2 Concentrationsupporting

confidence: 88%

Section: Photosynthesismentioning

confidence: 99%

Section: Co 2 Concentrationmentioning

confidence: 99%

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Ecophysiology of tea

Costa

Mohotti

Wijeratne

2007

Braz. J. Plant Physiol.

118

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“…The first 10 cm below the plucking table consists of the maintenance foliage, which is responsible for the production of photo-assimilates needed to support the growth of new shoots (Manivel & Hussain, 1982a). Okano et al (1995) found that 85% of photosynthesis ) the associated reduction in interception of solar radiation has a significant impact on yield and long term plant vigour. The rates at which new shoots are able to grow is therefore retarded as a result of increased competition for a smaller pool of available photoassimilates.…”

Section: Discussionmentioning

confidence: 99%

Yield decline in mechanically harvested clonal tea (Camellia sinensis (L) O. Kuntze) as influenced by changes in source/sink and radiation interception dynamics in the canopy

Madamombe

Tesfamariam

Taylor

2015

Scientia Horticulturae

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Highlights• Mechanical harvesting removes foliage indiscriminately and decreases tea yield.• Desirable shoot number and mass are reduced under mechanical harvesting.• The maintenance layer is depleted in mechanically harvested bushes.• There are a greater number of strong sinks in mechanically harvested bushes.• Sink/source dynamics altered by mechanical harvesting. AbstractHigh labour costs and shortages and the cost of production has resulted in tea (Camellia sinensis (L) O. Kuntze) industries in central and southern Africa becoming unprofitable. This has led to the full mechanization of shoot harvesting, however, a reduction in yield has been observed with mechanical harvesting. It was hypothesized that the decline in yield as a result of mechanical harvesting is a result of the indiscriminate harvesting of shoots which leads to a change in sink/source and radiation interception dynamics within the canopy. As a result whole plant photosynthesis is impacted; which ultimately impacts tea bush productivity. Studies conducted at 2 Tingamira estate, Chipinge, Zimbabwe showed significant yield differences between hand plucking and machine harvesting treatments, with higher yields under hand plucking across all seasons (43 945 kg green leaf ha ) and ride-on machines (36 268 kg green leaf ha -1 ) (p<0.05). This reduction in yield was associated with a decrease in both the number and mass of desirable shoots over each season. The cause of this change was largely attributed to the indiscriminate removal of foliage by the machines which resulted in the proliferation of immature shoots, with an associated increase in sink strength and competition for available photo-assimilates. In addition, the depletion of the maintenance layer in mechanically harvested bushes, as indicated by reduced fractional interception of photosynthetically active radiation in the top 10 cm in these bushes and reduced photosynthetic rates in these bushes, suggests that these bushes were also source limited, as compared to hand plucked bushes. Therefore the changes in tea bush architecture, as a result of mechanical harvesting, resulted in changes in sink/source dynamics which led to a proliferation of immature shoots which competed for limited photo-assimilates.

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“…At the stage of internode elongation, heading and middle ripening, 13CO z (0.5g of barium carbonate) was generated by applying 5% lactic acid solution for 10 minutes inside the canopy frame (40 X 40 X 120 cm) covered with plastic film under a PAR of higher than 1700 J1E m-Z S-l between 11 a.m. and 13 p.m. (Okano et al, 1995). The six hills of rice plant were enclosed into the frame.…”

Section: Co Z Feeding Experimentsmentioning

confidence: 99%