| Plant Factory is a kind of efficient agricultural production method,whichrelys on modern technology tocontrolindoor environment.It allows plants to continue growing and not controlled by the season and improves the production and resource use efficiency of the plant.As a soilless cultivation mode,hydroponics is widely used in the plant factory and gets good popularization and application in the field of vegetable.Compared with the traditional soil cultivation,hydroponics can economize the land resource;realize the full use of space.And it does not add fertilizer in hydroponic nutrient solution,can reduce pesticide residues.Moreover,it does not limited by season and reduces the length of the growing cycle.Atthe same time hydroponics improves the multiple cropping,production and economic benefit of plant.A hydroponics system of vegetables provides nutrient elements for the vegetablesthrough the nutrient solution.So the research of hydroponics nutrient solution formula and concentrations is vital for the development of the hydroponic technique.Biogas slurry as a by-product of biogas by Deep Flow Technique duction is a kind of renewable resources.The use of biogas slurry can improve the effective utilization of resources and get full re-utilization in the recycling process.The study found that there is a lot of nutrition elements of vegetables grow in the biogas slurry.And it not only contains vitamins but alsoinvolvesplentifulcellulases,protein,antibiotics and a variety of growth hormonethat help the growth of vegetables.Chosing the Hong Kong glass brittle leaf lettuce as experiment material,adopted the Deep Flow Technique,studied the effects of different concentration of biogas slurry on hydroponic lettuce growth,quality,the water use efficiency,the mineral dynamic absorption,photosynthetic and chlorophyll fluorescence characteristics.(1)The result showed that the biogas slurry could bring out a obvious promotion of the leaf area,yield,nutrient and water use efficiency of lettuce,which increased significantly with increasing of biogas slurry concentration among 10%,20% and 40% dosage.However those decreased to some extent among 60% and 80% concentration,the excessive biogas slurry concentration was not conducive to the growth of lettuce.The hydroponic lettuce had a higher absorption and utilization of N,P and Mg under the condition of the composite nutrient solution.While the demand of K for lettuce was relatively low.(2)The influence of biogas slurry on yield in different growth stages of hydroponic lettuce was consistent.Appropriate biogas slurry increased the yield of lettuce and it increased generally with the increase of concentration in a certain range.The yield was the highestof treatment which used the 20%and 40% concentrationof the biogas slurry inmiddle and later growing stage,respectively.And it was 66.97% higher than control treatment.Soluble sugar content increased significantlywith increasing concentration of the biogas slurry,andthe treatment of 40% biogasslurrywas the highest one in a group.The soluble protein content of lettuce increased generally with the increase of concentration in a certain range.However,the nitrate content of lettuce reduced gradually when the biogas slurry concentration was low.Furthermore,the content of vitamin C was correlated with biogas slurry concentration.(3)The research of different concentration of complex nutrient solution showed that: The effect on yield and quality of hydroponic lettuce was obvious under different concentration of nutrition solution.Through principal component analysis,we had synthesized numerous assessment indicators,and extracted two principal components.And theacumulative percent of two principal componentspresented 86.622% of total variance.According tocalculate the integrated score for thetwo principal components,we concluded that the 1.0 concentration of complex nutrientwasoptimal forhydroponiclettuce.Moreover,complex nutrient solutionincreased the optimal/maximalquantum yield of PS ? and reduced the non-photochemical quenching of hydroponicslettuce.So,complex nutrient solutionwasuseful in improvingphotosynthetic capacity andreducingthermal dissipation of lettuce. |
PDF Full Text Request