Effect of waterlogging on carbon isotope discrimination during photosynthesis in <i>Larix gmelinii</i>

2017-08-07T04:46:28Z (GMT) by Fang Li Atsuko Sugimoto
<p>Soil moisture is a major factor controlling carbon isotope discrimination (Δ<sup>13</sup>C), which has been demonstrated to decrease under dry conditions in many studies; however, few studies on Δ<sup>13</sup>C under waterlogging condition have been conducted. In this study, a pot experiment was conducted with <i>Larix gmelinii</i>, a major larch species in the east Siberian Taiga, to investigate the effect of waterlogging on Δ<sup>13</sup>C during photosynthesis. Assimilation rate and Δ<sup>13</sup>C<sub>RD</sub> (instantaneous Δ<sup>13</sup>C calculated with Rayleigh distillation equation) decreased drastically soon after waterlogging, followed by recovery in their values, which was caused by a change in stomatal conductance. Thereafter, assimilation rate decreased gradually, whereas Δ<sup>13</sup>C<sub>RD</sub> decreased more gently. These results were thought to be caused by the decrease in both stomatal conductance and carboxylation. Our results indicate that extreme wet events may cause a decrease in Δ<sup>13</sup>C, which is important information for detecting flooding events in the past using tree-ring isotope analyses and for studying impacts of flooding on plants in areas where waterlogging might occur.</p>