The genus Trapa possesses three distinct photosynthetic organs,including submerged leaves,floating leaves,and adventitious roots.In this study,we compared the anatomical structures and photosyn-thetic characteristics of these organs at different growth stages of Trapa quadrispinosa Roxb.Results showed that:(1)Submerged leaves exhibited a simpler structure compared to the bifacial anatomy of floating leaves;(2)Adventitious roots at both the juvenile and mature stages retained typical root structures and evident chloroplasts;(3)Significant differences were observed in chloroplast size and morphology among submerged leaves,floating leaves,and adventitious roots;(4)Floating leaves contained significantly higher levels of chlorophyll a(Chia),carotenoid(Car),and total chlorophyll(ChIs)compared to other organs,while juvenile adventitious roots and floating leaves exhibited higher chlorophyll b content(Chlb);(5)Floating leaves demonstrated superior photosynthetic efficiency,with higher maximum photochemical quantum yield(Fv/Fm),actual photochemical quantum yield(YⅡ),and photochemical quenching(qP)compared to the other organs.(6)Based on oxygen exchange rates,the order of the four photosynthetic organs from high to low was juvenile adventitious roots＞submerged leaves＞floating leaves＞mature adventitious roots.Overall,during the seedling stage,photosynthetic capacity was higher in adventitious roots than in sub-merged leaves.In contrast,during the adult stage,floating leaves surpassed adventitious roots in photo-synthetic capacity.
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