Response of leaf traits and photosynthetic fluorescence characteristics
of Fraxinus malacophylla seedlings to rainfall patterns during dry and
rainy seasons
Abstract
Global climate change has led to a shift in rainfall patterns. And as
water is an essential ingredient for plant photosynthesis, shifts in
rainfall patterns will inevitably affect plant growth. In this study,
the response of leaf traits and photosynthetic fluorescence properties
of Fraxinus malacophylla seedlings to rainfall patterns during the dry
and rainy seasons was investigated using a natural rainfall duration of
5 d (T) and an extended rainfall duration of 10 d (T+) as rainfall
intervals; and a monthly average rainfall as control (W), with the
corresponding rainfall treatments of a 40% increase in rainfall (W+)
and a 40% decrease in rainfall (W-). The results showed that Pn, Gs,
and Tr basically all tended to increase and then decrease with
increasing rainfall in the dry season, and generally reached the highest
under the W treatment; and Pn, Gs, Ci, and Tr mostly remained high at 5d
relative to 10d; PI was overall higher under the W treatment throughout
the dry season. Extending the rainfall interval at the beginning of the
rainy season significantly reduced Fm; throughout the rainy season, Gs,
Ci, and Tr basically showed a decreasing trend with increasing rainfall,
reaching the highest under the W-treatment, and mostly higher at 5d than
at 10d. These results suggest that natural rainfall intervals and
natural rainfall amounts are more favorable to the growth of Fraxinus
malacophylla seedlings in the dry season; reduced rainfall and multiple
rainfalls in the rainy season tend to promote photosynthesis in Fraxinus
malacophylla. This study reflects the different survival strategies of
Fraxinus malacophylla under different rainfall patterns, as well as
providing a theoretical basis for understanding how Fraxinus
malacophylla can grow better under rainfall variability and for future
management.