Fig. 2

Correlations between the Gs and Pn of tea grown under conventional agriculture (panel A) and sod culture (panel B) in four seasons (●=spring, ▼=summer, ■=fall, ◆=winter, The solid ones are CA and the hollow ones are SC.) monitored from June 2019 to May 2020. Plants were subjected to light irradiations of 0, 5, 10, 15, 25, 50, 75, 100, 200, 400, 800, 1,200, 1,500, 1,800, and 2,000 μmol m^− 2 s^− 1 PPFD for 75 min. Each symbol represents the average of five mature leaves on one plant, and five plants were randomly selected for tillage and season treatments. Each line represents the time point of 48 values (two seasons multiplied by 15 PPFD) from the model’s validation datasets. The correlation coefficients (r) are calculated and significance (p) is at the 0.0001 probability (*****) level