| Hydroponic culture is the dominant cultivation method of factory production.At present,hydroponic vegetables are being paid attention by producers and consumers.Leafy vegetables are a kind of crop that is easy to enrich nitrate,and the potential harm of nitrates to human body is getting more and more attention.The lettuce cultivation experiment of "Laccuca sativa L." was conducted.By setting different nitrogen concentrations in nutrient solution and different nutrient solution pH adjustment strategies,the experimental data were used to establish and validate the relationship between the nitrogen uptake model of lettuce cultivated under different nitrogen concentrations and the relationship between plant weight and nitrogen concentration in hydroponic culture menu.The concentration of liquid nitrogen was optimized,and the effects of different nutrient solution pH adjustment strategies on the growth and quality of hydroponic culture were compared to optimize the management of nitrogen concentration and pH control in nutrient solution to provide theoretical basis for the regulation of nutrient solution in hydroponics vegetables..The main findings are as follows:(I)The appropriate nitrogen concentration is conducive to the rational distribution of lettuce crown and root biomass,and obtain a higher effective yield.Increasing the nitrogen concentration of nutrient solution was beneficial to increase the total soluble sugar content of lettuce.With the increase of nutrient nitrogen concentration,the contents of vitamin C and nitrate of lettuce increased first and then decreased.With the increase of nitrogen concentration,the yield of the hydroponic culture system will increase first and then decrease.T3 had the best lettuce yield,and the yield per plant was 482.11%,53.53%,14.48%and 32.49%higher than that of T1,T2,T4 and T5 treatments,respectively.Nitrogen concentration will affect the growth and quality of the plant.(2)The fresh weight of hydroponic lettuce first increased and then decreased with the increase of nitrogen concentration.The optimum nitrogen concentration of lettuce was 9.69 mmol/L,which was determined by the relationship between the lettuce yield and the nutrient solution nitrogen concentration.Under conditions,lettuce yields higher yields.(3)Different kinds of inorganic acids were used to adjust the pH of the nutrient solution.The amount of inorganic acid used was different.The amount of use was HN03>Mixed Acids>H3P04>H2S04.And compared with other treatments,the pH of nutrient solution changes little after adjusting the pH of nutrient solution with H3P04.The scientific nutrient solution pH regulation strategy provides a good root environment for hydroponic crops,which helps the growth of crops and promotes the absorption of nutrients by crop roots.This experiment is based on the use of different types of inorganic acids,providing a more reasonable nutritional pH regulation strategy for hydroponic crops.Through experimental studies,it has been shown that using Mixed Acids can improve the yield and quality of hydroponic lettuce.(4)Using the experimental data and the inverse method,the fitting parameters of the relationship between nitrogen uptake factor and nitrogen concentration were obtained,and then the nitrogen uptake model of hydroponic lettuce root was established,which provided convenience for the application of the nitrogen uptake model of hydroponic lettuce root.The study on the law of nitrogen uptake in hydroponics lettuce root can provide a theoretical basis for knowing the nitrogen concentration of hydroponic nutrient solution,improve the nutrient use efficiency,and use the relationship between nitrogen concentration and yield.Use the concentration for optimal management.The pH of the nutrient solution was regulated based on optimization of nutrient solution nitrogen concentration.To achieve reasonable regulation of nutrient solution is of great significance to promote the sustainable development of hydroponic agriculture in China's facilities. |
PDF Full Text Request