Evaluating P Balance in P-Use Efficient Transgenic Romaine Lettuce Using Algae As an Alternative P Fertilizer.

Phosphorus (P) is a critical resource for human in two ways: 1. it is one of the major elements required for crop production; 2. human need clean drinking water while P is the major element causing toxic algal bloom in fresh waters. This study tackles these two challenges by focusing on P-use efficiency (PUE) and P recycling. PUE: AVP1 transgenic crops have been shown to have the potential to perform better under P limited condition and to have faster growth rate. Thus, less P and less time are required to grow AVP1 crops. P recycling: Scenedesmus dimorphus is one of the algae strains using for algal biofuel production. It also provides an alternative avenue for recapturing P. A prototype of sustainable P agricultural system is tested in this study by applying S. dimorphus to grow AVP1 crop- AVP1 romaine lettuce. P balance will be measured in algae, soil (P fractionation), lettuce (TP, TN, DNA, RNA, and protein), and leachate. Preliminary results show that S. dimorphus stunts plant growth, especially under adequate P treatment where N is particularly high. We suggest that applying algae as fertilizer may require pretreatment of the algae.