Growing media and plant nutrition: Searching for environment and product quality

Crop production in soilless media requires that an adequate supply of all the elements essential for plant growth be maintained. In greenhouse tomato production in circulating systems such as the Nutrient Film Technique (NFT), this is achieved by the use of a combination of automated control of electrical conductivity (EC), periodic chemical analysis and changes in the nutrient concentrations according to the changing nutritional needs of the crop. We have shown that there are beneficial effects of increasing the EC level of the re-circulated NFT nutrient solution with NaCl or NaCl/KCl on tomato fruit quality without yield reduction; under growing conditions prevailing in Easter Canada, increasing the salinity level of the nutrient solution up to 3.2-5.6 mS cm(-1) (i.e. 60% higher than normal) will increase tomato fruit sugar and acid contents which are related to better tomato taste. In the areas of nutrient supply optimization and fertilizer use efficiency, we have shown that the closed rockwool culture system can reach similar, and even better, tomato and sweet pepper yield and fruit quality than the conventional open rockwool system.