Abstract: The shade-endurance and photosynthesis characterstics of American blackberry‘Hull’were studied under light transmittance of 100% , 50% , 25% and 13%. The result showed that the net photosynthetic rate ( Pn) had two peaks at 9: 00 and 13: 00 respectively in a day, under full light with ‘Wuxiu’
phenomenon. There was only one Pn peak appeared at 11: 00 after shading. No significant differences were found between full light and 50% light treatment in branch and leaf growth, leaf thickness, palisade and sponge tissue, fresh-leaf mass per dm² , dry-leaf mass per dm², per fruit mass and soluble solid content. Chlorophyll content was significantly higher in 50% light than that in full light. When light transmittance below 25% , the branches grew excessively and the leaves became yellow, and no flower buds formed. Itwas indicated that American blackberry has good shade-endurance, moderate shading is helpful to its growth and development.

Key words: Blackberry, Shading, Growth, Photosynthetic characteristics