ISHS Acta Horticulturae 744: I International Symposium on Human Health Effects of Fruits and Vegetables
PRODUCTION OF HYDROPONICALLY GROWN CALCIUM FORTIFIED LETTUCE |
| Authors: | C. Neeser, N. Savidov, D. Driedger |
| Keywords: | Lactuca sativa, calcium uptake, hydroponic, temperature, dry matter |
| DOI: | 10.17660/ActaHortic.2007.744.33 |
| Abstract:
Calcium is the mineral nutrient most commonly deficient in modern diets. Leafy vegetables can be an excellent dietary source of calcium, and are a good alternative for individuals with a diet low in dairy products. Increasing the calcium content in leafy vegetables could further improve their nutritional benefits, which is likely to be of value to consumers. As part of an ongoing project on enhancing calcium content in vegetables through fertilization management, we measured how foliar calcium levels and yield of leaf lettuce (Lactuca sativa) are influenced by the calcium concentration in a hydroponic nutrient solution when grown under two temperature regimes. Our principal objective was to determine whether a significant increase in calcium content of lettuce could be achieved. The experiment was set up across six growth chambers as a completely randomized split-plot design with temperature (21°C and 28°C) as the main-plot factor and calcium concentration of the nutrient solution (50, 100, 150 and 300 ppm) as the sub-plot factor. We found that when grown at 28°C in the solution containing 300 ppm Ca, the acid extractable Ca in fresh lettuce leaves increased from an average of 179 mg/100 g to 229 mg/100 g. This was not the case when the plants were grown at 21°C. High levels of Ca in the hydroponic solution did not result in a significant yield loss compared to the treatment with the lowest Ca concentration. Under the more favourable temperature, increased calcium also resulted in increased tissue strength, as measured by the force required to cut through 3 leaves. These results suggest that calcium fortified lettuce could be produced in a hydroponic system by increasing the concentration of calcium in the nutrient solution. | |
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