Abstract:

This study analyzed the effect of root restriction (potted cultivated) on carbohydrate metabolism in ‘Luoyanghong’ tree peony (Paeonia suffruticosa luoyanghong) leaves. The result showed that root restriction significantly reduced the net photosynthetic rate (P_n), sucrose phosphate synthase (SPS) activity and acid invertase (AI) activity of tree peony leaves. The declined SPS activity and AI activity in tree peony leaves showed that both source and sink strength were inhibited by root restriction. Before anthesis, sucrose and starch levels were significantly lower in root restriction tree peony leaves than that in control. However, from flowering-stage to late-flowering stage, sucrose and starch were accumulated in root restriction tree peony leaves mainly because of the low sink strength which limited the driving force to transport sucrose to sink organ and to hydrolyze starch. Hexose content in root restriction tree peony leaves were lower than the control overall and its change was smooth during anthesis period. The reduced P_n of root restriction tree peony was mainly because of the lower level of sink strength, and the reduction of leaf area and accumulation of carbohydrates in leaves can also explain it to a certain extent.

Key words: root restriction, tree peony, carbohydrate metabolism, leaf