Figure 1.

Net photosynthetic rate (Pn) as influenced by various concentrations of exogenous melatonin following cold stress. Two years-old tea (Camellia sinensis L.) seedlings of Longjing 43 were pretreated with various concentrations of melatonin (10, 50, 100, 200, and 500 µM) and challenged with cold stress (−5 °C for 3 h) in temperature-controlled chambers. Pn was measured in mature tea leaves after a 3 h recovery from cold stress. Each data point presents the mean of six replicates (± S.D. (standard deviation)). Means denoted by different letters are significantly different (p < 0.05) based on the Tukey’s test.