Photosynthesis of Young Shoots on Greenhouse ‘Jinmudan’ Tea Plant

Objective Photosynthetic characteristics of young shoots at developmental stages on ‘Jinmudan’ Tea plant in a greenhouse were analyzed for improved cultivation.

Method A portable GFS-3000 photosynthesis measurement device was used to determine the net photosynthetic rate (P_n), transpiration rate (T_r), maximum net photosynthetic rate (P_nmax), saturated light intensity (LSP), and light compensation point (LCP) of “small unfurled” shoots (SUFS) and “medium unfurled” shoots (MUFS) located on top of branches of Jinmudan Tea plant. The collected data were fitted with light exposure to formulate a response function using the modified rectangular hyperbolic model.

Result The measurements on P_n of the shoots ranged 2.63-4.74 μmol·m⁻²·s⁻¹ with the 1^st MUFS on a plant being the lowest and the 3^rd MUFS the highest, while T_r ranged 2.31-5.97 mmol·m⁻²·s⁻¹ with the 1^st MUFS being the lowest and the 2^nd MUFS the highest. Among the young shoots on a plant, the greatest P_nmax of 7.40 μmol·m⁻²·s⁻¹ and LSP of 1208.10 μmol·m⁻²·s⁻¹ were found on the 3^rd MUFS and the lowest of 3.20 μmol·m⁻²·s⁻¹ and that of LSP of 867.03 μmol·m⁻²·s⁻¹, on the 1^st MUFS. The LCP ranked as 1^st MUFS at 32.95 μmol·m⁻²·s⁻¹ > 2^nd MUFS at 25.93 μmol·m⁻²·s⁻¹ > 3^rd MUFS at 20.53 μmol·m⁻²·s⁻¹.

Conclusion In general, P_n of MUFS was greater than that of SUFS. The 3^rd MUFS could more efficiently utilize strong or weak light as well as have a greater overall photosynthesis potential.