Rates of net photosynthesis (P N ) and transpiration (E), and leaf temperature (T L ) of maintenance leaves of tea under plucking were affected by photosynthetic photon flux densities (PPFD) of 200−2 200 µmol m −2 s −1 . P N gradually increased with the increase of PPFD from 200 to 1 200 µmol m −2 s −1 and thereafter sharply declined. Maximum P N was 13.95 µmol m −2 s −1 at 1 200 µmol m −2 s −1 PPFD. There was no significant variation of P N among PPFD at 1 400−1 800 µmol m −2 s −1 . Significant drop of P N occurred at 2 000 µmol m −2 s −1 . PPFD at 2 200 µmol m −2 s −1 reduced photosynthesis to 6.92 µmol m −2 s −1 . PPFD had a strong correlation with T L and E. Both T L and E linearly increased from 200 to 2 200 µmol m −2 s −1 PPFD. T L and E were highly correlated. The optimum T L for maximum P N was 26.0 °C after which P N declined significantly. E had a positive correlation with P N .Additional key words: leaf temperature; photosynthetic photon flux density.
Finding promising purple tea germplasm that would target new tea products for diversification and value addition boost the tea industry’s economic growth. Accordingly, 10 tea germplasm viz. TRA St. 817, TRA St. 293, TRA St. 400, TRA 177/3, TRA 376/2, TRA 376/3, TRA 427/7, TRA P7, TRA P8, and TV1 were evaluated in terms of gas exchange parameters, multiplication performance, and biochemical markers such as chlorophyll, carotenoids, and anthocyanin content, which are related to the purple tea quality. The investigated gas exchange and biochemical parameters revealed significant differences. Germplasm TRA St.817 was physiologically more efficient (24.7 μmol m–2 s–1), followed by TRA St. 293, exhibiting the highest net photosynthesis, water use efficiency (19.02 μmol mmol–1), carboxylation efficiency (0.73), chlorophyll fluorescence or photochemical efficiency of PSII (0.754) and mesophyll efficiency (ci/gs ratio: 2.54). Net photosynthesis was positively correlated with water use efficiency, carboxylation efficiency, mesophyll efficiency, and photochemical efficiency of PSII (r = 0.965**, 0.937**, 0.857**, 0.867**; P = 0.05), respectively, but negatively correlated with the transpiration ratio (r = −0.878**; P = 0.05) based on Pearson correlation analysis. The total anthocyanin content (4764.19 μg.g–1 fresh leaf weight) and carotenoid content (3.825 mg.g–1 fresh leaf weight) were highest in the TRA St.817 germplasm, followed by germplasm TRA St. 293 (2926.18 μg.g–1 FW). In contrast, total chlorophyll content was significantly low (1.779 mg.g–1 fresh weight), which is very suitable for manufacturing purple tea. The highest carotenoid concentration in TRA St. 817 was 3.825 mg.g–1 FW, followed by TRA P8 (3.475 mg.g–1 FW), favoring the formation of more volatile flavor constituents. The promising germplasm, TRA St 817, has a multiplication success rate of 91.4% through cleft grafting. The outcome reveals that TRA St.817 is a promising germplasm that can be used to make speciality teas, i.e., purple tea.
Partitioning of 14 C-labelled photosynthates to various parts of un-pruned tea clones TV1 and TV25 was assessed in vivo by exposing maintenance leaves to 14 CO 2 at monthly intervals throughout the year. The plants from shoot apex to root tip were divided into twelve components to assess the allocation and retention of 14 C-photosynthates by the maintenance foliage. Out of the total photosynthates produced by the maintenance leaves, only 11.08 % was allocated to the commercially useful harvestable two and a bud shoots which is accepted as the harvest index of tea. The photosynthetically active maintenance leaves retained 19.05 % while 24.56 % was distributed to the branches. The bottom and the top parts of the trunk utilized 7.44 and 7.21 %, respectively. The thick roots at the base of the trunk, medium sized roots, pencil size roots, and feeder roots imported 7.28, 7.72, 7.65, and 8.01 % of 14 C assimilates, respectively. Except retention by leaves, all the plant parts of vigorous clone TV25 required higher percentage of assimilates than TV1. The mean quantities of net photosynthates utilized by the stem and the roots were 69.37 and 30.63 %, respectively.
The objective of this study is to correlate the genetic diversity among tea cultivars with drought tolerance/susceptibility on the basis of morphological, physiological and molecular markers. Twelve highly polymorphic inter simple sequence repeat primers targeting the tea dinucleotide repeats predominantly present in drought stressed transcripts were used to screen out the germplasms into two groups showing drought tolerance and susceptible characteristic with polymorphic information content of 0.3. A similarity index of 0.58 was observed among the cultivars. Morpho-physiological diversity among the cultivars was studied using eighteen morphological and two physiological markers. Correlation studies showed significant association between the ranks of the morpho-physiological distances and molecular genetic distances at P=0.05%. The dinucleotide repeats targeted along with morpho-physiological correlation can be used in tea breeding for drought tolerance as the markers are in sync with the long term field trials based on which the plants were classified for drought trait.
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