Leaf traits related to productivity in Populus deltoides during the post-flooding period

Abstract

Flooding stress induces changes in trees at plant and leaf level that can reduce growth and productivity. In this work, we explored changes in leaf traits related to productivity during the post-flooding period in three poplar clones with different degrees of flooding sensibility. Our hypothesis was that changes in leaf traits could lead to a higher photosynthetic activity in the post-flooding period to compensate for the reduction in carbon fixation under flooding. Plants were grown in pots in a greenhouse. Flooding was induced by filling the pots with tap water up to 5 cm over the surface soil for 28 days. After this period, flooding ended and plant recovery was followed for 44 days. Flooding decreased total leaf area, stomatal conductance and photosynthetic rate, but leaf size, stomatal, leaf area, chlorophyll and Rubisco content were not affected. Stomatal index was reduced in one clone and leaf thickness was increased in another one. During the post-flooding period, the formerly flooded plants of all clones produced leaves with increased area and thickness compared to the control plants, but specific leaf area and chlorophyll and Rubisco content were not altered. Stomatal index was only decreased in one clone. The leaves expanded in the postflooding period did not increase their photosynthetic capacity, but had a higher water use efficiency and a lower stomatal conductance. The plants compensated for the reduced growth under flooding by substituting the leaf area loss instead of increasing the photosynthetic activity.