Abstract：In order to explore and analyze the potential photosynthetic ability of deep green tissues
inside stem of asparagus lettuce and possible maintain mechanism，so as to provide theoretical reference for
improving the yield and quality of asparagus lettuce，this paper took field planted asparagus lettuce as material
and leaves as reference，contrastively detected the chlorophyll fluorescence characteristics in the upper，
middle and lower segments of deep tissue inside the stem，and chlorophyll，water and zeatin contents; and
analyzed the relevance between them．The results showed that the values of maximum photochemical efficiency
Fv/Fm in the middle and upper stem segments were above 0.75，amounting to the leaves of many other higher
plants．While，the Fv/Fm value in the lower stem segment was relatively lower．Seeing from the results
of chlorophyll fluorescence induction，the photochemical energy consumption of the upper and middle stem
segments occupied bigger proportion than the lower segment．While，tissues in the lower segment took a
larger proportion of constitutive energy dissipation．Besides，The relative electron transport rates in tissues of
each asparagus lettuce stem were significantly weaker than that in leaves，but its absolute values were not low
as compared with the leaves of many other higher plants．The content of chlorophyll based on fresh weight in
leaves was significantly higher than that in stem tissues，of which that in the middle segment stem tissue was
the highest．Stem tissues contained more water and zeatin content than the leaves．Especially，these contents
in the middle segment tissues were the highest．The contents of chlorophyll，water and zeatin in each segment
of stem tissues were positively correlated．Based on these data，we believed that the deep tissues of asparagus
lettuce stem had stronger photosynthetic potential．The high content of zeatin could promote the tissues in stem
keeping long-term green state under dark condition．At the same time，chlorophyll in these green tissues could
be a matter maintaining high water contents in stem and directly influencing the yield and quality of asparagus
lettuce．
