Source: CONNECTICUT AGRICULTURAL EXPERIMENT STATION submitted to
EFFECT OF FERTILIZER AND ENVIRONMENT ON COMPOSITION AND NUTRITION VALUE OF HYDROPONIC LETTUCE
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0217083
Grant No.
(N/A)
Project No.
CONH00575
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Nov 15, 2008
Project End Date
Nov 14, 2012
Grant Year
(N/A)
Project Director
Gent, M.
Recipient Organization
CONNECTICUT AGRICULTURAL EXPERIMENT STATION
PO BOX 1106
NEW HAVEN,CT 06504
Performing Department
HORTICULTURE & FORESTRY
Non Technical Summary
There are more than 50 growers in Connecticut who use greenhouses for vegetable production. Over the last 20 years, there has been a resurgence of vegetable production in greenhouses and high tunnels, related to an increase in direct retail to consumers from farm stands. Vegetable producers would like to know the benefit to human nutrition of the crops they grow. They would be eager to adopt practices that would enhance nutritional benefit, if this translated to increased interest and income from Connecticut consumers. By manipulating the plant environment, it is possible to increase the production and/or the quality of specific compounds important for the nutritional or industrial value of specific plants. Research in this area has the potential to significantly increase the economic returns for greenhouse operations involved in vegetable production. However, practical information is limited on manipulating metabolites of value to human nutrition as affected by environmental conditions and cultural systems and practices. Lettuce or salad greens will be grown in water solution. The rate of plant growth, appearance and quality at harvest, and tissue composition will be measured and related to changes in light, temperature, and nutrient solution composition. The experimental results will be simulated with plant physiology-based mathematical models. This modeling effort will increase understanding of the internal processes that affect plant composition. IMPACTS Improved nutrient delivery systems with recycling of nutrient solutions that maintain optimum plant health and quality will minimize fertilizer inputs and the impact on the environment. Improved value of vegetables, in terms of human nutrition, will increase cash value and desirability of locally grown crops produced in greenhouses.
Animal Health Component
75%
Research Effort Categories
Basic
25%
Applied
75%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2041430101075%
2061430102025%
Goals / Objectives
OBJECTIVES Develop greenhouse environment and fertilizer protocols to maintain high nutrition values of vegetable crops grown in various seasons of the year. Determine the variation in tissue metabolite concentrations as a function of time of day, and define the time of harvest that optimizes human nutrition value. Develop a simplified model of metabolism within lettuce plants that can predict the season and diurnal variation in metabolite concentrations OUTPUTS Evaluate environmental control methods that enhance the nutritional values of certain greenhouse vegetable crops. Report at growers meetings on the daily and seasonal variation in composition of greenhouse vegetables grown in Connecticut.
Project Methods
Lettuce or salad greens will be grown in water solution. The rate of plant growth, appearance and quality at harvest, and tissue composition will be measured and related to changes in light, temperature, and nutrient solution composition. The experimental results will be simulated with plant physiology-based mathematical models. This modeling effort will increase understanding of the internal processes that affect plant composition. It will also have the power to predict combinations of environment and fertilizer that will optimize tissue composition with respect to human nutrition. A complete dataset of lettuce growth and composition throughout the season of the year will be a thorough test of the model. The model should be able to predict both this seasonal variation, as well as the effect of nitrate withdrawal in each season. Furthermore plant harvests in both morning and afternoon will define the diurnal variation in metabolite concentrations of lettuce. These variations are likely to change with season.

Progress 11/15/08 to 11/14/12

Outputs
OUTPUTS: A model was developed to relate growth and composition of hydroponic lettuce to fertilizer and environment in the greenhouse. PARTICIPANTS: Dr. Martin Gent is an emeritus scientist at the Connecticut Agricultural Experiment Station. Mr. Michael Short is a technician at the Connecticut Agricultural Experiment Station. Other collaborators and contacts are commercial growers: Two Guys from Woodbridge, Hamden CT Starlight Gardens, Durham CT Woodbury Farms, Woodbury CT And secondary schools: Sound School, New Haven CT TARGET AUDIENCES: The model of hydroponic lettuce and comparison with experimental results was presented to an international audience in Quebec CA (100). Experience in hydroponics production resulting from data collection and evaluations was used to offer advice to several growers (5). The effect of environment on composition of salad greens was presented to an audience of growers (50) in Manchester NH. PROJECT MODIFICATIONS: Project terminated on 1 July 2009

Impacts
Several growers have recently started producing salad greens in greenhouses and high tunnels, and lettuce in hydroponicis. In part this is due to information developed by this project and previous projects on this subject.

Publications

  • Gent, M.P.N. 2010. Measurement and Modeling of Diurnal Variation of Nitrate and Sugars in Lettuce. Acta Horticulturea (in press).
  • Gent, M.P.N. 2009.Changes with season of nutrients in salad greens grown in high tunnels. Proceedings New England Vegetable and Fruit Conference, Manchester NH.