Effects of different rootstocks on diurnal variation of photosynthesis of Red Globe grape

The purpose of this study was to determine the effects of environmental factors on grape photosynthesis so as to offer the theoretic basis for choosing and application of rootstock in production,and discuss the mechanism of rootstock-scion interaction.The grapevine of Red Globe grape taken as scion was grafted onto different rootstocks,LDP-294(Vitis piasezkii Maxim.var.pagnucii) and Beida.The net photosynthetic rate(Pn),transpiration rate(E),stomatal conductance(Gs),photosynthetic active radiation(PAR),and intercellular CO2 concentration(Ci) of two grafted cultivars and self-rooted individuals of Red Globe grape were measured with portable Ci-310 gas analysis system under natural conditions.The results showed that the daily variation of net photosynthetic rate and transpiration rate in the leaves of two grafted cultivars appeared single-peak curve,while photosynthetic active radiation and intercellular CO2 concentration appeared double-peaks curve.The daily variation of all the indices except for stomatal conductance rate appeared single-peak curve in self-rooted.The net photosynthetic rates of the two grafted cultivars were higher than that of self-rooted.The stomatal conductance and transpiration rate were the two dominant factors affecting the photosynthesis of Red Globe grape.The photosynthetic performances of Red Globe grape grafted with different rootstocks varied.The rootstocks of LDP-294 and Beida could apparently increase the photosynthetic capacity of Red Globe grape.