EFFECT OF SHADING LEVELS BEFORE HARVESTING ON PRODUCTIVITY AND GREEN TEA QUALITY OF KIM TUYEN VARIETY IN SUMMER

Green tea production in Vietnam is now becoming cradles for the country tea industry. Yield and quality are always the pillars for this commodity. In this research, the impacts of different shading levels, under shading on yield potential and fresh material quality were evaluated. The study was conducted for Kim Tuyen variety in summer season in Phu Tho province. Four tested shading levels were 90%, 70%, 50% and full sun (the control), applied 14 days prior to harvest. The study confirmed that the Kim Tuyen variety yielded significantly higher than the control in the treatments of 70% and 50% provided shade, reached 8.61 tons/ha and 8.38 tons/ha, respectively. However, by providing 90% shade, tea yield was reduced significantly. In terms of drinking quality of the outcome green tea product, the treatments of 70% and 90% shade stood at the top two of organoleptic tasting quality, whereas the treatment of 50% shade was not significantly different in comparison to the control. The organoleptic tasting score of these top treatments reached 17.3 - 17.4 points. Especially, they demonstrated a remarkable high score in aroma and taste. Finally, with the exception of tea mosquito bugs, the detected number of other main pests found to be reduced when higher levels of shade provided, including leafhopper, red mites, and thrips. Consequently, this treatment provided the highest net benefit for green tea production, reached VND 118.5 million/ha.