| This paper focuses on the scientific problem of the interaction between water-fertilizer-dissolved oxygen-temperature coupled quality and efficiency mechanism and irrigation flux of greenhouse vegetables.Through the combination of indoor climate chamber simulation and two-year greenhouse experiment,and using comparative design,orthogonal design,uniform-precision rotatable central composite design and quadratic saturation D-optimal design method,the study of the effect of greenhouse water-fertilizer-dissolved oxygen-temperature coupled irrigation on quality and efficiency mechanism of vegetables(tomato,fruit cucumber,lettuce)and its mathematical model was carried out systematically.The study was carried out systematically to investigate the effects of water-fertilizer-dissolved oxygen-temperature coupling on crop growth,photosynthesis,yield,quality,water use efficiency,soil microorganism,soil enzyme activity,soil oxygen content,soil respiration rate,soil water content,soil conductivity,soil temperature,and the mathematical model of each index,coupling effect,and optimal combination scheme.It provides a theoretical basis and technical support for the promotion of greenhouse vegetable quality and efficiency and water-fertilizer-dissolved oxygen-temperature coupled irrigation technology.The main research results are as follows:(1)The effects of dissolved oxygen in different irrigation water and soil temperature on the growth,photosynthesis,quality,yield,and soil microenvironment of vegetables were studied by comparative design.The mechanism of improving the quality and efficiency of vegetables in the greenhouse and intelligent climate incubator by aerobic irrigation and soil warming was revealed,It enriched the soil microbial biomass,promoted the growth of vegetables(plant height,leaf area index),increased the chlorophyll content and photosynthetic rate of plants,increased the yield and dry matter accumulation of vegetables,and improved the quality of vegetables.The better irrigation water dissolved oxygen was 9.0 mg/L for tomato and fruit cucumber,and the better soil temperatures were 26.1? and 20.6? for tomato and 26.06? and 19.11? for fruit cucumber in spring-summer and autumn-winter,respectively,and the better irrigation water dissolved oxygen for lettuce was 8.5 mg/L,and the better soil temperature for lettuce was 20?.The relationships between dissolved oxygen(DO)of irrigation water and soil oxygen content(SOC),between geothermal pipe temperature(TW)and soil temperature(TS),and between salinity of irrigation water(IS)and soil conductivity(SEC)were established.Compared to the control treatment,tomato yield increased by 17.51%and 15.09%and fruit cucumber yield increased by 22.47%and 28.04%in the spring-summer and fall-winter aerated irrigation better treatment(03),respectively.Tomato yield increased by 18.15%and 18.58%and fruit cucumber yield increased by 30.24%and 25.39%in the better soil warming treatment(T3),respectively.(2)The effects of different soil water-fertilizer-dissolved oxygen-temperature coupling on vegetable growth,photosynthesis,quality,dry matter accumulation,yield,and water use efficiency were studied by orthogonal design method,and the mechanism of vegetable water-fertilizer-dissolved oxygen-temperature coupling in the greenhouse and smart climate incubator was revealed,the main indicators of growth,photosynthesis,dry matter mass accumulation and yield of tomato and lettuce increased with the increase of single factor irrigation quota,fertilizer application,dissolved oxygen and soil temperature,and the main indicators of quality decreased with the increase of irrigation quota and increased with the increase of dissolved oxygen of irrigation water,fertilizer application and soil temperature.The main indicators of quality decreased with the increase of irrigation quota and increased with the increase of irrigation water dissolved oxygen,fertilizer application,and soil temperature.Based on the principal component analysis,the optimal treatment for both tomato and lettuce was T8(A3B2C1D3).The optimal irrigation quota for greenhouse tomato(T8)was 5760 m3/hm2,fertilizer application(N-P2O5-K2O)was 150-50-75 kg/hm2,dissolved oxygen was 6.0 mg/L(average soil oxygen content 15.99%),and ground The heat pipe water temperature was 41.0?(the average soil temperature in spring and summer was 25.41?,and the average soil temperature in autumn and winter was 20.38?),At this time,the tomato yield in spring and summer(autumn and winter)was 89653 kg/hm2(89357 kg/hm2),irrigation water use efficiency 15.56 kg/m3(15.51 kg/m3),water use efficiency 22.18 kg/m3(24.62 kg/m3),reference crop evapotranspiration 781.42 mm(504.83 mm),and crop coefficient of 0.52(0.72),respectively.Tomato yield increased by 23.07%and 33.61%in spring-summer and autumn-winter T8,respectively,compared to the control treatment.(3)The coupled effect of soil water-fertilizer-dissolved oxygen-temperature in greenhouse tomato and fruit cucumber was studied,and the mathematical models between each element of water,fertilizer,dissolved oxygen and temperature and the main indexes of growth,photosynthesis,quality,and yield of greenhouse tomato and fruit cucumber,respectively,as well as the comprehensive evaluation model of each index was established by using the uniform-precision rotatable central composite design and quadratic saturation D-optimal design.The order of the effect of water-fertilizer-dissolved oxygen-temperature coupling on the main indicators and composite scores of greenhouse tomatoes and fruit cucumbers was:irrigation quota>fertilizer amount>dissolved oxygen>geothermal pipe water temperature.The main indicators and composite scores increased with increasing irrigation rate,fertilizer application,dissolved oxygen,and geothermal water temperature in the experimental range,and the main indicators of tomato and fruit cucumber quality decreased with increasing irrigation rate in the experimental range and increased with increasing fertilizer application,dissolved oxygen and geothermal water temperature in the experimental range.The interaction of high water and low temperature,low water and high temperature,high fertilizer and low temperature,low fertilizer and high temperature was beneficial to enhance the net photosynthetic rate,transpiration rate,and leaf area index of the tomato plant.Medium irrigation quota and high dissolved oxygen were beneficial to improve the net photosynthetic rate of fruit cucumber leaves.Low fertilizer and high dissolved oxygen or high fertilizer and low dissolved oxygen were more beneficial to improve the chlorophyll content of fruit cucumber leaves.The interaction of high fertilizer and high temperature was beneficial to increase the content of vitamin C in tomato fruit,the interaction of low irrigation quota and high temperature was beneficial to increase the content of total soluble sugar and lycopene in tomato fruit,the interaction of low irrigation quota and high fertilizer was beneficial to increase the content of total acid and soluble solid in tomato fruit,Low irrigation quota and high fertilizer or low irrigation quota and medium fertilizer can improve the soluble protein content,vitamin C content,soluble total sugar content and total acid content of fruit cucumber,while high irrigation quota and low fertilizer can reduce the nitrate content of fruit cucumber.The interaction of high irrigation quota and low temperature or high irrigation quota and low fertilizer was beneficial to increase the dry matter accumulation,yield,and comprehensive index score of the tomato plant.High irrigation quota and high fertilizer were beneficial to increase the yield and dry matter accumulation of fruit cucumber.The optimal water-fertilizer-air-heat coupling scheme for greenhouse tomatoes and fruit cucumbers in this region is recommended as follows:spring-summer tomato irrigation quotas 5142?5330 m3/hm2,fertilizer amount(N-P2O5-K2O)150-50-75-165-55-81 kg/hm2,dissolved oxygen 7.9-8.1 mg/L and geothermal pipe water temperature 34.1?36.1 ?.Autumn and winter tomato irrigation quotas 4988-5210 m3/hm2,fertilizer amount(N-P2O5-K2O)154-51-76?168-56-82 kg/hm2,dissolved oxygen 7.9?8.2 mg/L and geothermal pipe water temperature 34.4?36.3 ?.The irrigation quota for fruit cucumber in spring and summer ranged from 3923?4044 m3/hm2,fertilizer amount(N-P2O5-K2O)from 123-36-87?130-38-91 m3/hm2,dissolved oxygen from 7.7?7.9 mg/L and geothermal pipe water temperature from 34.9?36.7?,while the irrigation quota for fruit cucumber in autumn and winter ranged from 3527?3670 m3/hm2,the amount of fertilizer applied(N-P2O5-K2O)122-35-86?128-37-90 kg/hm2,dissolved oxygen 7.8?8.0 mg/L and geothermal pipe water temperature 35.9?37.4 ?.The optimal treatment for tomato was determined to be treatment T10 based on principal component analysis,and the average yield of tomato yield T10 increased by 36.29%and 43.32%over T17-T20 in spring-summer and fall-winter,respectively.The optimal treatment for fruit cucumber was determined as T15 treatment,and the yield of fruit cucumber T15 increased by 54.42%and 45.00%compared to the control in spring-summer and fall-winter,respectively.(4)A mechanistic model of leaf area index and dry matter accumulation of greenhouse tomato based on water-fertilizer-dissolved oxygen-temperature coupling was developed,and the simulation accuracy of the model was verified and evaluated to increase with the increase of irrigation quota,fertilizer application,dissolved oxygen in irrigation water,and soil temperature.The model was applied under the following conditions:greenhouse tomato irrigation quota 2880 m3/hm2?5760 m3/hm2,fertilizer application(N-P2O5-K2O)75-25-45 kg/hm2?225-75-105 kg/hm2,dissolved oxygen 4.0 mg/L?9.0 mg/L,geothermal pipe water temperature 25??45?,and greenhouse The average temperature of the greenhouse was 15.06 ??41.62 ?,the average relative humidity of the greenhouse was 22.68%?72.53%,the average CO2 concentration of the greenhouse was 251 ppm?477 ppm,the average outdoor temperature was 15.30??41.20?,and the average relative humidity of the outdoor was 19.44%?85.68%. |
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