[Diurnal change of photosynthetic characteristics of native Vetiveria zizanioides in western Guangdong].

The determinations on the photosynthetic parameters of native Vetiveria zizanioides in Western Guangdong in autumn showed that the net photosynthetic rate (P(n)) of V. zizanioides had a diurnal change with two peaks, transpiration rate (T(r)) and stomatal conductance (G(s)) were similar with P(n), while intercellular CO2 concentration (C(i)) was in adverse. There was a significant positive correlation between P(n) and photosynthetic active radiation (PAR) (P < 0.01) , T(r) and PAR (P < 0.01), air temperature (T(a)) and relative humidity (RH) (P < 0.01), and G(s) and T(a) (P < 0.05). Same environmental factors had different effects on P(n), T(r) and G(s), and PAR had most intensive effect on the photosynthesis of V. zizanioides. Among the test photosynthetic parameters, T(r) was most sensitive to the environmental factors.