Controlled Environment Agriculture

Lettuce

Commercial Demonstration Feasability Study

Our work in high-tech greenhouse production (we call this 'CEA-style' production) began with a review of all the levels of controlled environment agriculture available, hydroponic system types, and an evaluation of crops that would be suitable for such a production system. Commercial site requirements are enumerated along with specifics for each potential CEA crop such as environmental requirements, common hydroponic production methods, plant disease risk, and market potential.

Commercial Demonstration Facility

A small 1/5 acre glass gutter-connected CEA greenhouse was constructed and began hydroponic 'raft' or 'deep trough' lettuce production in 1999. The first year's worth of sales and operating costs may be found in a report on the Commercial Demonstration Facility page to the left.

Modeling of Evapotranspiration

Mathamatical models of plant growth of many different emphases may be found in the research performed by CEA scientists over the years. This model was developed for NASA to attempt to identify when plants are stressed very early before they demonstrate visual signs of stress. Evapotranspiration in plants drives the movement of nutrients and water from the root environment through the plant. Measurements from the nitrate content of the root environment and the transpiration rate of the plants can be combined to determine when plants are stressed so that the stressors may be identified and steps to eradicate them can be eliminated as soon as possible.

Modeling of Nitrate and Root/Shoot Partioning in Lettuce

Lettuce can accumulate dangerous (to humans) levels of nitrate when grown very slowly (usually in cold temperatures). Standards exist in Europe to limit how high nitrate levels may be for winter-produced lettuce. This project identified the minimal growth rate that must be maintained to avoid a harmful level of nitrate in the plant tissue. In addition to the relationship between plant growth rate based on temperature, an uptake rate based on the nitrogen content of the nutrient solution was developed.