Abstract:PAR (photosynthetic active radiation) is an important factor affecting tomato ( Lycopersicon esculentum Mill.) plant growth, development and yield. But high irradiation may not always be beneficial to the plant at all growth stages. The effects of two strengths of shading (40% and 75% increases in shaded area) for 8 days at three growth stages (i.e. early flowering (EF), peak flowering (PF) and late flowering (LF)) on photosynthesis, dry matter accumulation and allocation of dry matter to roots, stems an...