Abstract:

Based on the daily meteorological data from 83 weather stations in Guizhou province from 1961 to 2025 and the ratio of tea polyphenol content to amino acid content (TP/AA) of spring tea collected from seven sampling sites (Meitan, Huaxi, Fenggang, Tongzi, Daozhen, Zheng'an and Duyun) for the years 2013, 2016, 2018, 2021 and 2023, this study employed methodologies including fuzzy mathematics, stepwise regression and Gaussian mixture models. Seven pre−harvest periods (3d, 5d, 7d, 9d, 11d, 13d and 15d prior to harvesting) were established. The average climate suitability index for each period was calculated. Key factors affecting TP/AA were screened by correlation analysis, enabling the simulation of spring tea quality and climate quality assessment. The results showed that the climate suitability for the spring tea season in Guizhou province from 1961 to 2024 ranged from 0.62 to 0.81. Overall, there was an increasing trend over time, with 93% of stations showing an increasing trend and 37% of stations showing a significant increase (P<0.05). The spatial distribution showed a decreasing trend from south to north and from east to west in Guizhou. Average climate suitability 15d before harvesting was identified as the major factor affecting the phenol to amino acid ratio. By further dividing the 15-day pre-harvest period into five consecutive sub-periods, a TP/AA simulation model was jointly constructed, which demonstrated good simulation accuracy for both the training and test sets (P=0.009). Based on the comprehensive climate suitability index and simulated phenol to amino acid ratio, Gaussian mixture clustering was employed to establish thresholds and grades for evaluating the climatic quality of spring tea: comprehensive index＞0.75 or simulated ratio≤4.98 as superior, 0.67<comprehensive index≤0.75 or 4.98<simulated ratio≤5.78 as excellent, 0.56<comprehensive index≤0.67 or 5.78＜simulated ratio≤6.40 as good and comprehensive index≤0.56 or simulated ratio＞6.40 as common. These results provide a scientific basis for climate−based quality evaluation and harvest timing regulation of spring tea.

Key words: Guizhou spring tea, Pre?harvest period, Climate suitability, Stepwise regression, Climate quality evaluation