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Effects of Different Rates of Gibberellic Acid (ga3) on Shoot Growth Dynamics and Yield of Mature Clonal Tea (camellia Sinensis L.)

T. Ahmed*
SSO
Bangladesh Tea Research Institute, Srimangal–3210, Moulvibazar, Bangladesh

W.A.J.M. De Costa
Professor
Department of Crop Science, Faculty of Agriculture, University of Peradeniya, Sri Lanka

M.A. Wijeratne
SRO
Tea Research Institute, Low-Country Station, Ratnapura, Sri Lanka

Abstract/ Executive Summary:

The yield of tea (Camellia sinensis L.) consists of tender shoots which are produced on axillary buds of tea bushes on the plucking table. In the present study, it was hypothesized that foliar application of Gibberellic acid (GA3) could influence shoot growth dynamics and yield components of tea and ultimately affected its yield. Therefore, the above hypotheses were investigated on a mature clonal tea (cv. TRI2025) in a field experiment at the Tea Research Institute, Low-Country Station, Ratnapura, Sri Lanka. Different rates of GA3 were used as treatments and sprayed on the foliage at monthly intervals which continued up to six months. GA3 showed a significant effect on length of shoot replacement cycle (LSRC), shoot extension rate, average shoot fresh weight, formation of banji shoots, harvested shoot density and ultimately affected on the harvested yield of tea. Higher made tea yield was observed in GA3 @ 500ppm which was similar with GA @ 200ppm but significantly different with GA3 @ 100ppm and the control, respectively.

Keywords: GA3, Shoot growth dynamics, Shoot density, Tea yield

Location: Tea Research Institute, Low Country Station, Ratnapura

Start Date: 00-05-2012

End Date: 00-11-2012

Program Area: Resource Development and Management

Commodity: Tea, Gibberellic acid (GA3)

Objectives:

Nandi et al. (1995) stated that GA3 induced bud-break earlier by two weeks while ABA and NAA were found to be inhibitory to shoot growth. Therefore, this study was undertaken to investigate the effects of different rates of Gibberellic acid (GA3 ) on shoot growth dynamics, yield components and yield of tea.

Methodology:

The experiment was carried out at the Tea Research Institute, Low Country Station, Ratnapura (60 40'N, 800 25'E and 30 m amsl) and continued over a period of six months (from May 2012 to November 2012). It was a single factor experiment having four treatments of different rates of Gibberellic acid (GA3 ) namely, no application of GA3 (control); GA3 @ 100ppm (a.i.); GA3 @ 200ppm (a.i.) and GA3 @ 500ppm (a.i.). The experimental design was a completely randomized design with four replications and all together there were 16 experimental plots. 10 bushes were demarcated in each plot. A standard tea cultivar TRI2025 was used and tea bushes were 12-year old with double-hedge spacing (0.6m x 0.9m x 1.5m) and were in the first year of the third pruning cycle. Application of fertilizers and cultural practices were carried out according to the recommendations of TRI, Sri Lanka. The GA3 were sprayed at monthly intervals and on every occasion control tea plants were sprayed with water.

Plucking was done in the morning on weekly rounds for estimation of the plot yield in g per plot. After taking the fresh weight of harvested leaf, counting was done for each plot to get the number of active shoots, banji shoots and then total number of harvested shoots. The number of shoots for each plot was then converted into the number of harvested shoots per bush and m-2 .

To know the effects of treatments on shoot growth dynamics, six shoots each having three leaves with an active bud were randomly selected from the centre of the bush from each plot at two months intervals. Selected shoots were plucked and tagged for future identification. Three of the tagged shoots were plucked when they reached at the standard of two leaves with active bud. The following measurements were made on these harvested shoots e.g. fresh weight per shoot and length of shoot replacement cycle (LSRC) for attaining the standard of two leaves with a bud. The other three tagged shoots were left without harvesting until they become dormant. The following measurements were made on these shoots e.g. days required for the shoot to become dormant and the number of leaves that were produced before becoming dormant. To get the shoot extension rate, after completing the harvesting operation in weekly round five (5) remaining shoots (arimbu) from the centre of the plucking table were tagged from each plot which was almost similar in size. At the time of tagging the length of each shoot was measured by a ruler and recorded. After a week, at the time of harvesting the length of each tagged shoot was measured again and the difference between the two readings of a particular shoot gave the value of shoot extension rate (mm week-1) of that shoot.

Source of Information: Tea J. Bangladesh, 43: 1-9, 2014 ISSN: 0253-5483

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Shoot growth dynamics and yield-related parameters of tea were significantly affected by the foliar application of GA3. Having the greater shoot extension rate, greater shoot weight, shorter LSRC, higher harvested shoot density and less banji shoots the highest yield of tea was reported in GA3 @ 500ppm which was similar with 200ppm but significantly different with others. Hence, to maximize the tea yield, it may be suggested to apply GA3 @ 200ppm for a few rounds during the dry period of the year

Knowledge Management: Journal