| Abstract: | In Cucumis sativus L. net photosynthesis of leaf number 12 increaseduntil 12 d after its unfolding and then decreased gradually. Sink demand was varied by imposing the number of fruits perplant without changing the number of leaves per plant. Net leafphotosynthesis did not respond to sink demand during the first16 d of fruit growth. Subsequently, a substantial reductionin photosynthesis was found only when all fruits were removed.This reduction was accompanied by a decrease in the rate oftranspiration, indicating a higher stomataL resistance. Neither starch nor mono- and disaccharides accumulated noticeablyat reduced sink demand, suggesting that there was no end-productinhibition of photosynthesis. Dry matter content of the leaves increased and specific leafarea decreased when sink demand was reduced. When modelling cucumber production, effects of sink demand onleaf photosynthesis can be ignored. Key words: Cucumis sativus, photosynthesis, sink-source, sink demand |
