Abstract: In this study, the currently cropped Rehmannia glutinosa was leaf-clipped to simulate the shortage of photosynthate in successively cropped R. glutinosa, and ¹⁴C-istope tracer and ELISA techniques were adopted to analyze the distribution of photosynthate and the levels of endogenous hormones in successive R. glutinosa, aimed to approach the source-sink relationship of the phosynthate and to explore the mechanism of continuous cropping obstacle of R. glutinosa. Leaf-clipping did not have the same impact as continuous cropping obstacle. The volume and activity of phosynthate pool under leaf-clipping were bigger than those under continuous cropping. The photosynthate in continuously cropped R. glutinosa was remained in shoot, suggesting that the low activity of the sink affected the transportation of the photosynthate. The levels of endogenous hormones also changed at the early growth stage of continuously cropped R. glutinosa. Our results suggested that the small volume and low activity of the sink could be an important factor limiting the development of R. glutinosa roots in continuous cropping. The feedback regulation of the sink to source by endogenous hormones inhibited the photosynthesis capacity and the partitioning of photosynthate to sink, resulting in the continuous cropping obstacle.

Key words: Bagging, Litchi chinensis, Fruit quality, Pesticide residue