UPASI TEA RESEARCH FOUNDATION

Nirar Dam BPO, Valparai-642 127 | Coimbatore (Dis), Tamil Nadu, INDIA.
Recognized by DSIR

PHYSIOLOGY OF GROWTH & DEVELOPMENT

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Agronomic practice influence dry matter production and favourable partitioning in tea. On field transfer, young tea plants showed growth inhibition due to apical dominance. When the apical meristem is removed by means of centering, dormant buds grow out and form new shoots. Growth retardants suppress apical dominance and induce the growth of latent buds without hindering the metabolic activities of the plant. Centering of young tea plants four to five months after planting is advantageous in promoting an early spread. Newly formed shoots allowed to grow freely are tipped at determined heights. Tipping enhanced effective canalization of assimilates in terms of root carbohydrates. The axillary and the accessory buds formed after two stage tipping contribute to canopy formation.

Pruning reduced the leaf area index drastically and the balance between the growth of shoots and roots is disturbed. The recovery of tea bush from pruning depends upon health of the bushes in terms of root carbohydrates. It also influences the favourable partitioning of dry matter in tea. A significant increase in promoter:inhibitor ratio was also observed on the application of Plant growth regulators (PGRs) which reduced the banji (dormant shoots) percentage significantly.

Tea plants have a rythemic growth pattern, dormancy and flush, coinciding with either management practice or unfavorable environmental conditions or a combination of both. Environmental conditions regulate the levels of endogenous promoter inhibitor ratio in the plant system. Plucking system determines the amount of maintenance foliage left on the bush. Continuous mother leaf plucking resulted in lower yield and retained excessive maintenance foliage. Harder form of plucking though resulted in higher crop, affected the ratio between the leaf and stem. Harvesting to mother leaf through dry spell led to sustained crop ensuring the normal metabolic functions.

Photosynthetically active functional units of the tea bush are considered for gross productivity. Continuous use of shears for harvesting in tea led to crop loss due to the physiological imbalance which in turn adversely affected the bush health. Photosynthetic rate declined due to the damage caused by shears on the maintenance leaf thereby affecting the metabolic activity significantly.

Increase in the abscisic acid content tilted the promoter:inhibitor ratio towards inhibitor side which in turn influenced the formation of dormant buds in tea. More number of banji shoots in the harvest, not only affects the productivity; they also deteriorate the quality of made tea to an extent. Responses of tea plants to applied plant growth regulator are encouraging. An increase in economic yield was noticed when plants were applied with commercial plant growth regulators without affecting either the quality or bush health. Foliar application of NK and antitranspirants imparts drought tolerance, sustaining physiological activities by regulating balanced water relations.

Tea leaves attain their peak efficiency in photosynthesis when fully expanded and remain photosynthetically active for longer period. A quadratic relationship existed between the age of a tea leaf and net photosynthetic rate. A progressive increase in photosynthetic rate was recorded for four months and then declined.

As the axillary bud unfolded the sink capacity decreased while the photosynthetic carbon assimilation capacity of maintenance leaf increased. There was a significant increase in photosynthetic efficiency from bud to fully expanded leaves. Expanding second and third leaves show a significant variation in fixing atmospheric carbon dioxide. One leaf and a bud showed a significantly higher sink capacity than two or three leaves and a bud. Plucking three leaves and a bud along with banjis seems to be the ideal standard which facilitates sink-induced photosynthesis, in turn enhancing productivity index.

As the distance between the “source” and “sink” increased, a substantial reduction in the mobilisation of photosynthates was noticed. Several factors were found to influence their mobilisation. When the photosynthetic rate increases the amount of assimilates translocated to the sink also increased dramatically. The maintenance leaves below 20 cm of the canopy would not be disadvantageous per se, but the synthesis and maintenance of superfluous amounts of photosynthates would require an increased expenditure of energy.

Pruning reduced the leaf area index drastically and the balance between the growth of shoots and roots is disturbed. The recovery of tea bush from pruning depends upon health of the bushes in terms of root carbohydrates. It also influence the favourable partitioning of dry matter in tea. A significant increase in promoter:inhibitor ratio was also observed on the application of Plant growth regulators (PGRs) which reduced the banji (dormant shoots) percentage significantly.