Morphological structure and photosynthetic adaptations in mulberry seedlings growing in low light to light intensity

In order to provide technical data for mulberry cultivation,adaptations of leaf,root and photosynthesis in mulberry seedlings during the course of transferring seedlings from low light in seedling greenhouse(27%of sunlight intensity)to sunlight in the field were researched,taking Qiuyu as experimental material.The results showed that the leaf thickness,palisade tissue thickness and ratio of chlorophyll a/b in mulberry leaves of transferred seedlings were slightly higher than those in low light and significantly lower than those in sunlight.Chlorophyll content in mulberry leaves of transferred seedlings was similar to that in low light and significantly higher than that in sunlight.Root dry mass per plant and ratio of root to shoot in transferred mulberry seedlings were significantly higher than those of mulberry seedlings growing in low light.Carboxylic efficiency of RuBP,light saturation point,the photosynthetic rate at light saturation in leaves of transferred mulberry seedlings were slightly higher than those in low light and significantly lower than those in sunlight,and apparent quantum yield was significantly higher than that of seedlings growing in low light.The changes of actual PSⅡefficiency and non-photochemical quenching in leaves of transferred seedlings alone with light density lay between lowlight and sunlight.Although thermal dissipation rate in leaves of transferred seedlings was higher than that of seedlings growing in low light,its photosynthetic energy was lower.It suggested that leaf morphological structure and photosynthetic energy in mulberry seedlings during the course of transferring seedlings from low light in seedling greenhouse to sunlight in the field could not recover to the capacity in seedlings growing in sunlight,and photosynthetic adjustments in transferred seedlings to sunlight depended on root dry mass increasing and status transferring.