Transplant Quality, Yield, and Heavy-Metal Accumulation of Tomato, Muskmelon, and Cabbage Grown in Media Containing Sewage Sludge Compost1

Abstract

Abstract Transplant quality, as measured by height and dry weight, of cabbage (Brassica oleracea L. Capitata group) and tomato (Lycopersicon esculentum Mill.) was lower for plants grown in media containing sewage sludge compost with a high heavy-metal concentration (HM) than for plants grown in peat-vermiculite (P-V) or low-metal (LM) sewage sludge compost media. Compost source had no significant effect on transplant quality of muskmelon (Cucumis melo L.) seedlings. Marketable yield of cabbage, tomato, or muskmelon was similar regardless of the media used to grow the transplants. The concentration of Zn, Cu, Mn, Ni, and Cd were significantly higher in transplants grown in HM media than in those grown in LM media. With the exception of Cd, metal levels in transplants grown in LM media were similar to those grown in P-V. Transplant media had little influence on the heavy-metal concentrations found in either foliar samples or the edible portions of the crops studied. Heavy-metal concentrations in foliar samples of all 3 crops were lower than those found in transplants. The lowest concentrations were found in tomato and muskmelon fruit, and in cabbage heads. The Cd concentrations in edible portions were very low regardless of the source of compost in the transplant media, indicating that sewage sludge composts, particularly those low in heavy metals, can be used safely in the growing media of vegetable transplants.