Comparison of photosynthetic characteristics of three litchi cultivars at full-bloom stage

Objective  To investigate the diurnal patterns and photosynthetic characteristics of the leaves of litchi (Litchi chinensis) at full-bloom stage, and provide references for cultivation and management of litchi at flowering stage.

Method  Under natural conditions, the photosynthetic parameters of three litchi cultivars including 'Feizixiao', 'Guiwei' and 'Nuomici' at full-bloom stage were measured using a LI-6400 portable photosynthesis system.

Result  The curves of diurnal changes in net photosynthetic rate (Pn) had two peaks and clear midday depression for all three cultivars, the first peak was measured at 10:30, and the second peak was at 13:30. The average daily Pn of 'Nuomici' (3.76 μmol·m^-2·s^-1) was significantly higher than those of 'Feizixiao' (2.38 μmol·m^-2·s^-1) and 'Guiwei' (2.41 μmol·m^-2·s^-1). Pn of three cultivars were significantly positively correlated with photosynthetic available radiation (PAR). In addition, Pn of 'Guiwei' was significantly positively correlated with air temperature (θ_a), and Pn of 'Nuomici' was significantly positively correlated with stomatal conductance (Gs).

Conclusion  PAR is the primary ecological factor influencing Pn of the three litchi cultivars, and the effects of other factors on photosynthesis of litchi leaves vary among different cultivars.