Solar energy has is widely distributed, abundant, green, and pollution-free, leading to the best choice for the clean energy. Particularly, the greenhouse effect and energy crisis are ever ever-intensifying in the context of population growth and energy consumption. Among them, nanofluids exhibit the excellent photothermal conversion performance and thermal conductivity, indicating the promising potential in the field of solar heat collection. Therefore, the nanofluids can be expected to introduce be introduced as a collecting medium in the vacuum tube collectors. However, it is often required to improve the heat collection efficiency of the vacuum tube solar collectors. This study aims to prepare and screen the high-performance nanofluids with the high stability and the photothermal conversion properties. Application experiments were conducted to optimize the graphite nanofluids in the greenhouse solar collectors. Firstly, five heat transfer media were selected as the water, titanium dioxide, silicon dioxide, copper oxide, and graphene nanofluids. The photothermal conversion was ranked in the descending order of graphene nanofluid, copper oxide nanofluid, silicon dioxide nanofluid, titanium dioxide nanofluid, and water. Considering both cost and stability, the graphene nanofluid was selected, due to its strong photothermal conversion performance, excellent stability, and low cost. Secondly, a systematic investigation was made to explore the effects of dispersants, the order of material addition, ethylene glycol content, ultrasonic parameters, and dilution on the dispersion and stability of graphene nanofluids. An optimal preparation was developed for a stable ethylene glycol-water-based graphene nanofluid after dilution. Subsequently, the photothermal conversion experiments were performed on the ethylene glycol-water-based graphene nanofluid in both the direct-absorption and coated vacuum tubes. The results indicated that the instantaneous thermal efficiencies reached the maximum of 76.40% and 81.67%, respectively (compared with 41.70% for water) at the mass fractions of 0.0030% and 0.0048% in the direct-absorption vacuum tubes. The thermal efficiency of graphene nanofluid was consistently higher than that of water during heating. In the coated vacuum tubes, the graphene nanofluid served as the heat transfer medium, leading to a greater temperature increase, compared with water, although the difference in thermal efficiency was relatively small. Finally, the ethylene glycol-water-based graphite nanofluid was applied into greenhouse solar collectors. Its impact on the crop growth was verified after the test. The temperature of coated vacuum tubes was higher than that of the uncoated ones after heating of 500 L of collector fluid on a typical sunny day in winter. There was the a greater increase in temperature, when using graphite nanofluid as the medium, compared with the water. The "coating + 0.00 06% graphite" demonstrated the best heat collection among the configurations. The temperature of the "coating + 0.000 6% graphite" system increased by 0.48 ℃ after 4.5-hour hours of sunlight. The average substrate temperature increased by 1.53 ℃, and the average temperature was 5.01 ℃ higher than that of the unheated substrate. As such, the fruit harvest time was advanced, due to the plant height, stem thickness, fruit yield, dry weight, and fresh weight of the warmed tomato plants. In summary, the ethylene glycol-water-based graphite nanofluids also exhibited the excellent stability and photothermal conversion, effectively enhancing the heat collection efficiency of solar collectors. The mass production and application of graphite nanofluids can be achieved to prepare the concentrated and diluted solutions, thereby reducing manual labor. This finding can also provide some insights and valuable references to prepare the nanofluids in a greenhouse.

Vapor pressure deficit (VPD), defined as the difference between the actual water vapor pressure and the saturation vapor pressure in the air, is a core indicator of atmospheric aridity. High VPD induces intensified water loss via plant transpiration, thereby constraining water uptake and photosynthetic capacity. The dynamic functions and molecular regulatory mechanisms of plasma membrane intrinsic proteins (PIPs), key aquaporins mediating rapid transmembrane water transport, remain unclear during plant responses to high VPD stress. In this study, we elucidated the regulatory role of SlPIP1;7 in regulating the multi-level adaptation strategy of tomato (Solanum lycopersicum) at the morphological, physiological, and molecular levels under high VPD conditions. The results indicate that, compared to wild-type (WT) plants, SlPIP1;7 overexpressing (OE) plants exhibit superior growth performance under high VPD conditions. The overexpression of SlPIP1;7 significantly enhances the reactive oxygen species (ROS) scavenging efficiency, effectively protecting plant cells from oxidative damage. This protective mechanism for maintaining ROS homeostasis is closely associated with stomatal function. The overexpression of SlPIP1;7 can regulate stomatal morphology, size, and aperture dynamics, thereby promoting efficient utilization of water and carbon dioxide and enhancing the overall physiological regulatory capacity of plants under stress conditions. Additionally, we identified the ethylene response factor SlERF4 as an upstream regulatory factor in this adaptive network. Yeast one-hybrid (Y1H) and dual-luciferase (LUC) assays demonstrate that the transcription factor SlERF4 can bind to the SlPIP1;7 promoter, enhancing its expression and functionality. This interaction further underscores the pivotal role of SlPIP1;7 in combating high VPD stress. In summary, our study elucidates the crucial function of SlPIP1;7 in plant response and acclimation to high VPD stress. These findings expand our understanding of the molecular mechanisms underlying plant acclimation to environmental stresses and provide a reference for future breeding strategies aimed at developing drought-resistant crops.

In order to solve the issue of limited heat storage capacity of assembled solar greenhouse wall, an assembled flexible composite wall incorporating heat storage, insulation, and waterproof functionalities was developed by integrating a heat storage layer within the wall structure. Initially, after evaluating the performance of various materials, premium surface and insulation materials were meticulously chosen and combined to create a flexible insulation wall. Subsequently, according to the different types and amounts of thermal storage materials on the surface of flexible insulation wall, six experimental treatments were designed in this study: The surface of A1, A2 and A3 wall were treated with the same amount of phase change hydrogel(PCH), water and sand thermal storage materials, respectively; The surface of A4, A5 and A6 wall were 5, 4 and 3 kg/m² PCH thermal storage materials, respectively. Finally, the wall performance was tested in four model greenhouses and the flexible insulation wall without thermal storage layer was taken as the control (CK) to analyze the thermal storage and insulation performance of the treatment wall by collecting related indexes such as indoor temperature, wall temperature and heat flux.The analysis of individual wall components revealed that the surface materials of aluminized woven cloth and black coated felt had excellent tensile and impermeable properties with the breaking force of 1.06, 0.56 kN and breaking elongation of 30.99 %, 65.91 %, respectively. In the insulation materials, the thermal resistance of recycled cotton, space cotton, and air column were 0.30, 0.50 and 0.76 (m²·℃)/W, respectively, which had the advantages of efficient insulation effect and low usage cost. When all treatments were tested in model greenhouses, the test results of A1, A2 and A3 showed that the heat storage effect of latent heat storage material of PCH was better than water and sand. This indicated that the A1 wall had the best heat storage and insulation performance and the maximum heat absorption and release per unit area were 0.91 and 0.73 MJ/m², respectively; Under typical sunny and cloudy conditions, the average indoor temperature of the A1 at night was 2.74 and 1.20 ℃ higher than CK and the average wall temperature at night was 7.33 and 2.34 ℃ higher than CK, respectively. The test results of A4, A5 and A6 showed that with the increase of the amount of PCH thermal storage material, the thermal storage and insulation effect of the wall gradually increased. This indicated that the A4 wall had the best thermal storage and insulation performance, and the maximum heat absorption and release per unit area were 1.48 and 1.13 MJ/m², respectively; Under typical sunny and cloudy conditions, the average indoor temperature of the A4 wall at night was 3.08 and 1.87 ℃ higher than CK and the average wall temperature at night was 7.16 and 3.02 ℃ higher than CK. The above analysis shows that the notable enhancement in heat storage and insulation efficiencies is achieved by incorporating a phase change heat storage layer within the flexible insulation wall.This study can provide theoretical basis for the design and material selection of flexible composite wall of assembled solar greenhouse in the future.

High atmospheric vapor pressure deficit (VPD) reduces the calcium (Ca) distribution in tomato (Solanum lycopersicum L.) fruits, severely reducing fruit mass. Reducing the VPD or increasing Ca fertilizer is an important measure to improve Ca distribution in fruits. However, the mechanism through which VPD and Ca regulate fruit Ca distribution remains unclear. This study investigated the effects of high and low VPD and Ca levels on Ca distribution and fruit mass based on carbon fixation, water transport dynamics, and pectin and Ca content and identified key differential genes and metabolites through transcriptome and metabolome analyses. The results showed that both reducing VPD under low Ca and increasing Ca under high VPD increased water and Ca transport to fruits. The increased Ca combined with pectin to form Ca pectinate, which effectively stabilized the cell wall and enhanced the fruit mass. Reduced VPD under low Ca increased the distribution of Ca to fruits but decreased the distribution of Ca to leaves. Lower Ca distribution in leaves increased their absorption of other nutrients, such as potassium, magnesium, copper, and zinc, which increased the stomatal size and density, thereby improving plant carbon absorption and assimilation efficiency. However, transcriptomic and metabolomic data indicated that carbohydrates, as important regulatory factors under drought stress, increased significantly under high VPD, thereby reducing the fruit water potential while improving fruit water and Ca absorption. Therefore, the carbon assimilation efficiency, water transport capacity, and differential genes and metabolites regulated Ca distribution. This work provides a theoretical basis for environmental and fertilizer management in greenhouse tomato production.