Photosynthetic induction is slower in young leaves than in mature leaves in a tropical invader, Chromolaena odorata

Abstract

Chromolaena odorata is a noxious invasive perennial herb in tropics and subtropics throughout the world. However, photosynthetic induction of this invader is not well understood. Here, we measured the induction of gas exchange and chlorophyll fluorescence in young and mature leaves of Chromolaena odorata. During photosynthetic induction, the young leaves exhibited higher biochemical and total limitations to photosynthesis than that of the mature leaves. Photosynthetic induction in this invader was affected by a mix of biochemical and stomatal limitations. Under a strong photosynthetic photon flux density, nonphotochemical quenching was rapidly activated to dissipate excessive light energy in both young and mature leaves. Furthermore, the induction of photosynthetic electron flow was faster than that of net photosynthetic rate for both young and mature leaves. The rapid activation of nonphotochemical quenching can dissipate excess light energy and regulate photosynthetic electron flow during photosynthetic induction, especially in the young leaves.

Keywords

• induction limitation; nonphotochemical quenching; photoprotection; photosynthetic electron flow.