10.1371/journal.pone.0088421.g007 Hu Yang Hu Yang Jinwen Li Jinwen Li Jingping Yang Jingping Yang Hua Wang Hua Wang Junliang Zou Junliang Zou Junjun He Junjun He Temporal dynamics of SPAD readings over leaf lifespan fitted to a piecewise function. Public Library of Science 2014 Agricultural production Environmental impacts Agroecology Agronomic ecology Ecosystems agroecology crops Crop management ecology ecosystems Artificial ecosystems Ecosystem modeling Plant ecology Plant-environment interactions spad readings lifespan fitted piecewise 2014-02-10 03:22:09 Figure https://plos.figshare.com/articles/figure/_Temporal_dynamics_of_SPAD_readings_over_leaf_lifespan_fitted_to_a_piecewise_function_/929332 <p>Leaf lifespan was divided into three growth stages: growth, function, and senescence. The leaf age difference is the difference in leaf physiological age between upper and lower leaves. The dynamics of leaf SPAD readings of upper and lower leaves were assumed to follow the same trajectory (piecewise function). Angle <i>β</i> served as an index of the SPAD reading distribution gradient.</p>