Abstract:

Abstract: In order to explore the photosynthesis light response to soil moisture of cassava South China 8 (SC8). We planted SC8 in pots with the range 20%～80% of soil relative water content (SRWC) . And measured the net photosynthetic rate (Pn) ,stomatal conductance (Gs) ,intercellular CO2 concentration (Ci) and several other parameters by employing LI-6400 portable photosynthesis system after planting about four weeks. The results showed that Pmax, AQY, LCPand LSP were little variation with the SRWC increased when the SRWC was more than 50%.The Pmax, AQY and LSP obviously decreased with the SRWC decreased when the SRWCwas less than 50%,but the LCP obviously increased with the SRWC decreased.The main effect on photosynthesis of SC8 both stomatal factors and non-stomatal factors. The dominant factor was stomatal when the light was low (PAR ≤ 400μmol ? m-2 ? s-1),but the non-stomatal factor was dominant factor when the light was high (PAR ≥ 600μmol ? m-2 ? s-1).The limitation function of stomatal and non- stomatal factors to photosynthesis was low SRWC rather than high SRWC.And the lower limit threshold value of appropriate SRWC for SC8’s photosynthesis probably was 50%.