Quantifying the impact of daily and seasonal variation in sap pH on xylem dissolved inorganic carbon estimates in plum trees.

摘要: In studies on internal CO2 transport, average xylem sap pH (pH(x)) is one of the factors used for calculation concentration dissolved inorganic carbon in ([CO2*]). Lack detailed pH(x) measurements at high temporal resolution could be a potential source error when evaluating [CO2*] dynamics. this experiment, we performed continuous ([CO2]) and stem temperature (T-stem), complemented with 30-min intervals during day various stages growing season (Day Year (DOY): 86 (late winter), 128 (mid-spring) 155 (early summer)) plum tree (Prunus domestica L. cv. Reine Claude d'Oullins). We recorded to calculate based T-stem corresponding measured [CO2]. No statistically significant difference was found between mean calculated instantaneous daily pH(x). However, using an value from different part than [CO2] estimate led error. The varied 3.25 +/- 0.01% under-estimation 3.97 * over-estimation, relative true data. Measured did not show variation, unlike [CO2], which increased declined night. As progressed, (3.4%, 5.3%, 7.4%) (5.43, 5.29, 5.20) decreased. Increase will increase its solubility according Henry's law, dissociation negatively affect Our results are first quantifying due interaction seasonal time scale. changes across season, but overall effect remained within range 4%. it possible that more substantial other species, particularly if sensitive (pHx > 6.5).