| Plant factory is an ideal growth facility for leafy vegetables in modern society.However,the high cost of construction,operation and equipment has seriously restricted its development.Among them,the cost of nutrient solution cultivation is high and the technology is complex,which is not easy for the first-line vegetable farmers to master.In order to solve these problems,this paper adopts the matrix cultivation method and carries out the shelf culture experiment of leaf lettuce in the ordinary solar greenhouse,in an attempt to provide the theoretical basis for the shelf culture technique of leaf lettuce.Firstly,the matrix thickness was investigated.Seedling matrix was adopted as the main substrate and three treatments were set with thickness of 6cm,10cm and 14cm.It was found that the thicker the substrate,the smaller the variation of temperature and water content of the substrate and the more stable the root environment was.The growth and quality of lettuce treated with 10cm and 14cm were significantly better than those treated with 6cm,but there was no significant difference between the two treatments.Considering the weight bearing and cost of the cultivation frame,it is considered that the substrate with 10cm thickness is suitable for the layered cultivation of leaf lettuce.In order to reduce the cost of substrate and improve the nutrients,peat and organic fertilizer were used to prepare,and the experiment was carried out with pure peat as the control(the thickness of the matrix was10cm).The results showed that: when peat: sheep manure: cow manure was 3:1:1,the yield of leaf lettuce per plant was the highest,more than 10% higher than CK.All organic fertilizer treatments improved the quality of lettuce,among which the comprehensive quality of peat: sheep manure: cow manure was 3:1:1,and the contents of chlorophyll,soluble solids and VC were 53%,46% and 76% higher than those of CK,and the soluble sugar content was twice as high as that of CK.After the application of organic fertilizer,the content of available nitrogen and available potassium in the matrix was 1.5～2 and 2.8～4.4 times of CK,respectively.Nitrogen,phosphorus and potassium decreased most rapidly in the growth period from 17 to24 days,and the changes of CK elements showed that leaf lettuce absorbed more nitrogen and potassium elements.In order to further explore whether the nutrients in the selected formula can fully meet the needs of the rapid growth period of leaf lettuce,a topdressing experiment was carried out on the basis of 3:1:1formula of peat: sheep manure: cow manure,a topdressing experiment was carried out.The results showed that after 18 and 28 days of planting,50g urea and 48g potassium sulfate,25 g urea and 24g potassium sulfate were added to each cubic meter respectively,the yield per plant of lettuce increased by 48%,the content of chlorophyll,soluble sugar and VC increased by 47%,36%,18% respectively,and the content of nitrate also increased,but within the safe range.The study on the micro environment effect of the trellis culture system also found that the uneven distribution of the culture environment affected the growth and quality of leaf lettuce.The light intensity of the middle and lower layers of the culture layer was lower,and the air temperature of the upper layer was higher.It is concluded that for leaf lettuce layered cultivation in solar greenhouse,peat: sheep manure: cow manure: 3:1:1 formula,substrate thickness of 10cm is appropriate,the middle and late top dressing management should be strengthened in the period of 17-24 days,urea with potassium sulfate is appropriate.In the process of layer-type cultivation,proper artificial light supplementation should be carried out for the middle and lower layers.In the high temperature weather,the ventilation of the greenhouse should be strengthened and the temperature of the upper layer should be adjusted. |
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