Studies On Lettuce Cultivating With Hymec Using Unusual Water Resources

Nutrient solution as the core of soilless culture relies on water strongly, so utilizing unusual water resources to confect nutrient solution not only can extend water source but also can reduce the cost, so applying unusual water resources to soilless culture has a wide foreground. But bad factors of unusual water resources limit the application on soilless culture. The root of plant cultivated by Hymec doesn't contact with nutrient solution, so it can reduce the effects of bad factors in nutrient solution on plant growth. Investigating the feasibility of applying Hymec on vegetable soilless culture using unusual water resources would provide a new way for unusual water resources utilization on agriculture.The author performed experiments on Italian very late bolt lettuce cultivated by Hymec and the thesis studied the effects of nutrient solution concentrations, seawater concentrations, heavy mental sewage on the growth,quality and so on , respectively. The main results were as follows:1. In a certain range( < 6 times), the plant height of lettuce cultivated by Hymec increased with nutrient solution concentration increasing. When the nutrient solution concentration≥6 times, plant height declined. The shoot fresh weight and water content in the treatment of 2 times nutrient solution were the biggest and these indicators of 4 and 6 times were the smallest. With the nutrient solution concentration increasing, nitrate content increased and nitrate,soluble protein and chrolophyll content were the biggest in the treatment of 6 times nutrient solution. The change of P content had the same trend and K content of 2 times nutrient solution was the biggest. Considering growth and quality synthetically, 2 times nutrient solution was the best for Hymec cultivation.2. The growth of lettuce cultivated by hydroponics with seawater at different concentrations was inhibited and with the seawater concentration increasing the inhibitive degree increased; the lettuce in the treatment of 50% and 75% seawater nutrient solution was dead to some extent. The inhibitive degree in the root was lighter than that of shoot. 10% and 25% seawater nutrient solution significantly reduced P and K content. It indicated that seawater nutrient solution at different concentrations all do injury to the lettuce, the injury was different according to seawater concentration and plant parts. 3. Hymec cultivation enhanced P and K content of 10% seawater treatment, decreased the injury of seawater nutrient solution to lettuce growth, the plant height,leaf width,leaf number,shoot fresh weight,shoot dry weight increased, the quality of lettuce with 10% seawater treatment was not significantly different with control except soluble sugar and nitrate. When the seawater concentration increased to 25%, the lettuce growth was significantly inhibited and with seawater concentration increasing the inhibitive degree increased, the lettuce of 75% seawater treament was dead to some extent. These indicated that using Hymec cultivation could alleviate the injury of seawater nutrient solution at a certain concentration to lettuce.4. Under heavy mental sewage treatment, Hymec cultivation could reduce Pb and Cd content of the lettuce, reduce the injury of Pb and Cd to the lettuce, promote the assimilation of P and K. Except for leaf number and chlorophyll, the plant height,leaf length,leaf width,shoot fresh weight,shoot dry weight,water content all were significantly higher than those of the lettuce cultivated by hydroponics using manual multiple heavy mental sewage. These indicated that Hymec does the function as physical barrier.