THE IMPACT OF MACHINE PICKING HEIGHT ON GROWTH, YIELD AND QUALITY OF SOME TEA VARIETIES IN THAI NGUYEN

Abstract

The study’s objective is to identify the appropriate height of the tea picking machine (the distance from light pruning of the previous year to the first pruning spot by machine in the next year) in Dong Hy district, Thai Nguyen province. The study has been conducted on the tea terraced-field with the yield of 12 tons per hecta per year where PH₁, LDP₁ and Trung du varieties have being planted. In the spring season, the tea plants have been plucked by hands, then by machine at the height of 5, 10 and 15cm from May to the late October. It has been shown that when we use machine to pick tea at the height of 10 cm and 15cm, the tea canopy grows better; the biomass of stemp, branches and leaves when pruning at the year-end and the tea bud yield have been higher than when we pick at the height of 5 cm. However, between 2 picking levels of 10 and 15cm, there has been no certain difference in the growth of the tea canopy and tea bud yield of all the tea varieties. At the different height levels when using picking machine, there has been no clear difference in the tea bud volume and quality of tea shoots. From the study results, the authors have proposed the process of picking tea by machine for the PH₁, LDP¹ and Trung du tea varieties as follows: plucking by hands on March and April, then picking by machine at 10cm of height above the old pruning spot and after that, using machine to pick at the spot 2-3 cm higher than the old one.