Abstract
The four experiments on agronomic practices were conducted at the Bangladesh Tea Research Institute (BTRI) Farm, Srimangal, Moulvibazar during the period from 1998 to 2001 in order to find out the optimum population density at different fertilizer levels and suitable pruning methods in young tea clone BT2 in the 1" experiment; as well as optimum pruning cycle, optimum plucking round and optimum plucking system in mature tea in 2nd, 3rd and 4th experiment, respectively. Five spacings namely, 0.90mx0.60m, 1.07mx0.60m, 1.07mx0.75m, 1.20mx0.75m and 1.07mx0.60m x 0.60m, that is, plant population of 18,518, 15,576, 12,461, 11,111 and 19,960 ha ̈1; three fertilizer doses of N, P2O, and K2O @ 20-100, 10-50 and 20-100 kg ha'', respectively were used and each of these fertilizer doses was splitted into three levels namely, Level 1 (20-10-20, 40-20-40, 60-30-60 and 80-40-80, Level 2 (30-15-30, 50-25-50, 70-35-70 and 90-45-90 and Level 3 (40-20-40, 60-30-60, 80-40-80 and 100-50-100 and used in the 1st, 2nd, 3rd and 4th year, respectively. Moreover, three young tea formative pruning operations namely, decentering, breaking and pegging were done in this study. Four types of 4-year pruning cycle combinations namely; LP- DS-MS-LS, LP-UP-DS-UP, LP-MS-DS-MS and LP-OS-DS-OS were practiced for determining the best pruning cycle in mature tea. Five plucking rounds starting from 6 days to 10 days and 2 plucking systems viz., Fish and Janam were included in the study. The highest plant population (19,960 ha ̈1) in spacing 1.07m x 0.60m x 0.60m with pegging and with fertilizer level 3 gave the highest yield in each of the four years study. The average data of 4 years study with the highest plant population 19,960 ha' gave 22.78% higher yield than that of currently maintaining plant density of 11,111 plants ha" with 1.20m x 0.75m spacing in Bangladesh. This could be because of the highest number of bushes per unit area of land with maximum plucking points per plant which contributed higher harvest at the initial stage of plants growth. Interactions between spacing and fertilizer, spacing and pruning as well as fertilizer and pruning failed to show any significant effect on the yield and other parameters. But correlation study showed a positive relationship between base diameter and tea yield and this could be due to the growth of healthy shoots responsible for higher yield from thicker base diameter of plants.
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Four-year pruning cycle of LP-UP-DS-UP gave 4.8% higher yield in mature tea than that of the currently practicing pruning cycle of LP-DS-MS-LS in Bangladesh. Six-day and Seven-day plucking round gave 1.55% and 5.46% higher yield, respectively than that of Ten-day round. Moreover, the shorter plucking round 6-7 day was found very congenial to follow during the peak period of plucking because the highest quality components (two leaves & a bud) was recorded higher from the shorter rounds (6-7 day intervals) than that of the longer rounds (8-10 day intervals). The number of shoots and shoot weight recorded higher from Janam system of plucking than those of Fish plucking and thus contributed 14.29% more yield than that of Fish plucking.
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This study revealed that the highest plant population of 19,960 ha at spacings of 1.07m x 0.60m x 0.60m with the highest doses of N, P2O, and K2O @ 40:20:40, 60:30:60, 80:40:80 and 100:50:100 kg ha' in 1st, 2nd, 3rd and 4th year, respectively with pegging method of pruning appeared as the promising agronomic practices for establishment of orthotropic type of young tea of BT2. A 4-year pruning cycle of the combination LP-UP-DS-UP adopting 7-day plucking round with Janam system of plucking emerged as the suitable cultural practices for the higher yield in mature tea of BT2 under the prevailing environmental conditions of BTRI Farm.