Cucumber plants (Cucumis sativus L. cv. Athene F1) were grown with four treatments: unrestricted root volume fruiting (UF); unrestricted root volume non-fruiting (UN); restricted root volume fruiting (RF); and restricted root volume non-fruiting (RN). Restricting root volume to 40 ml reduced leaf area, and by day 60 leaf area was only 20% that of unrestricted plants. Leaf area reduction in restricted plants was due to a combination of smaller and fewer leaves. Root restriction strongly depressed total dry matter production in both root and shoot. Significant differences of treatments in shoot and root growth rates were akpparent 30 days after sowing. RN plants had a 70% lower net photosynthesis (Pn), stomatal conductance (gs) and transpiration rate (E) measured on day 50, while root restriction had no effect on Pn in fruiting plants, although gs and E were significantly decreased due to restriction. Respiration capacity of restricted roots decreased sharply after day 24 compared with unrestricted root systems. Initially, O2 may have been the limiting resource and root respiration capacity a major factor involved in root restriction, since it causes imbalances in root growth substances and related hormones that alter the plant's morphology.