2014 ASHS Annual Conference

Bibb-type lettuce is one of the leading greenhouse vegetables grown in North America and the world. Almost all greenhouse lettuce is produced hydroponically using computerized production systems such as ebb and flow, NFT, and floating raft systems. Greenhouse production of lettuce is relatively small compared to field grown. But because it is clean and free from soil, its high quality is desirable by restaurateurs and home consumers. A greenhouse experiment at the Dr. James S. Craigie Research Center in Cornwallis, Nova Scotia was designed to test the effects of Stimplex^® extract (a derivative from Ascophyllum nodosum) on yield and quality of hydroponically grown greenhouse lettuce. Ascophyllum nodosum seaweed extract (ASE) treatments in combination with a standard hydroponic fertilizer were applied to the root systems of lettuce plants (Lactuca sativa var. Buttercrunch) through an ebb and flow system. Lettuce production of the ASE-treated plants was compared to fertilizer only treated plants. The number of new roots in the ASE-treated plants was shown to increase by up to 41% during the first 6 days after transplant. At harvest, head weight was shown to increase by as much as 27% in the ASE treatments. In addition, an increase in head quality was observed where 86% of the ASE-treated plants graded A or B compared to only 63% of the control plants. These results suggest that the inclusion of ASE into a standard hydroponic nutrient system promotes earliness, yield, and quality of hydroponically grown lettuce which results in a higher economic return for the user.