Effects of Plant Growth Regulators on Flower Abscission and Growth of Tea Plant Camellia sinensis (L.) O. Kuntze

The flowering of tea plant Camellia sinensis (L.) O. Kuntze consumes large amounts of water and nutrients and negatively affects the growth of tea plant. The effects of plant growth regulators, including ethephon, α-naphthalene acetic acid, salicylic acid, chlormequat, and paclobutrazol, were investigated on the abscission of flower buds and flowers on the tea plant. The occurrence of anthracnose Gloeosporium theae-sinesis Miyake and tea green leafhopper Empoasca onukii Matsuda on the tea plant were also investigated after exogenous application of these chemicals. Ethephon (at 800, 1200, and 1600 mg l−1), paclobutrazol (at 150, 300, and 600 mg l−1), and chlormequat (at 300 and 600 mg l−1) significantly promoted the abscission of flower buds and flowers and finally reduced the number of tea flowers in the tea plantations. These three compounds had almost no effect on the number of tea shoots. Moreover, paclobutrazol and chlormequat also suppressed the occurrence of anthracnose on the tea plant. Paclobutrazol and chlormequat induced the high catalase and peroxidase activities in the tea plant. In addition, the photosynthetic characteristics and biochemical components such as tea polyphenols in the tea plant leaves treated with plant growth regulators decreased significantly. There was a certain correlation between effects of ethephon and paclobutrazol on flower abscission and the expression of ACS and ETR. Overall, plant growth regulators could effectively reduce tea flowers and suppress anthracnose on the tea plant.