ROOT RESTRICTION AND SHADING EFFECTS ON SUMMER SQUASH

Abstract

Summer squash (Cucurbita pepo L.) was grown under greenhouse conditions in 0.35, 2.00, or 7.60 liter containers with full light or with 50% full light to determine the effects of root restriction and reduced light on crop growth and development. Leaf area was determined nondestructively over the course of the experiment, and destructive plant samples were taken weekly to determine dry matter accumulation and partitioning. The experiment was repeated to validate results. There was a decline in production of plant leaf area and dry matter accumulation in response to increased root restriction under full light conditions. However, under 50% light, root restriction had less impact on plant growth when comparing the 2.00 and 7.60 liter container plants. Under the most severe root restricting conditions, light level had little impact on leaf area production and dry matter accumulation. There were no consistent differences in leaf chlorophyll attributable to root restriction or reduced light; however, there was a trend for decreased leaf weight per unit of leaf area under low light conditions. Fruit dry matter production was notably diminished under severe root restriction in full light, and under all root environments under 50% light.