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Background The tea plant ( Camellia sinensis (L.) O. Kuntze) is one of the most economically important woody crops. Plastic greenhouse covering cultivation has been widely used in tea areas of northern China. Chlorophyll is not only the crucial pigment for green tea, but also plays an important role in the growth and development of tea plants. Currently, little is known about the effect of plastic greenhouse covering cultivation on chlorophyll in tea leaves. Results To investigate the effect of plastic greenhouse covering cultivation on chlorophyll in tea leaves, color difference values, chlorophyll contents, gene expression, enzyme activities and photosynthetic parameters were analyzed in our study. Sensory evaluation showed the color of appearance, liquor and infused leaves of greenhouse tea was greener than field tea. Color difference analysis for tea liquor revealed that the value of ∆L, ∆b and b/a of greenhouse tea was significantly higher than field tea. Significant increase in chlorophyll content, intracellular CO 2 , stomatal conductance, transpiration rate, and net photosynthetic rate was observed in greenhouse tea leaves. The gene expression and activities of chlorophyll-metabolism-related enzymes in tea leaves were also activated by greenhouse covering. Conclusion The higher contents of chlorophyll a, chlorophyll b and total chlorophyll in greenhouse tea samples were primarily due to higher gene expression and activities of chlorophyll-metabolism-related enzymes especially, chlorophyll a synthetase (chlG), pheophorbide a oxygenase (PAO) and chlorophyllide a oxygenase (CAO) in tea leaves covered by greenhouse. In general, our results revealed the molecular basis of chlorophyll metabolism in tea leaves caused by plastic greenhouse covering cultivation, which had great significance in production of greenhouse tea.

This review aims to provide a comprehensive overview of nano- and microscopic materials that can provide thermal radiation insulation without reducing visible light transmittance, thereby reducing heat loss and conserving energy in greenhouses. We also reviewed the radial and thermal properties of greenhouse covering materials. Fillers, colorants, reinforcers, and additives, as well as glass, plastic film, and plastic sheet materials, were discussed. Additionally, by searching for keywords like insulation film, insulation agent, and infrared insulation, compounds based on graphene and fullerene as well as phase transition materials (PCMs) that may be used for radiation insulation, we proposed their potential use in greenhouse covers. They can be divided into semi-transparent photovoltaic (PV) materials, zinc oxide-based film fillers, and silica filter films. We discussed the radiation heat insulation and light transmission characteristics of these materials. Nano-synthesis techniques were also investigated. Based on latest advances in the literature, future developments in the micro- and macroscale synthesis of nanomaterials will enable additional innovations in covering materials for greenhouse structures. A limiting factor, though, was the high sensitivity of PVs to external climatic and meteorological variables. The ability of materials used to make greenhouse covers to control the microclimate, reduce CO2 emissions, use less energy, and increase agricultural productivity, however, cannot be disputed. Similar to this, a thorough examination of the uses of various greenhouse technologies reveals that the advancements also have financial advantages, particularly in terms of reducing greenhouse heating and cooling expenses. The PCMs, which decreased greenhouse-operating costs by maintaining constant ambient temperatures, provide ample evidence of this.

Biochar is an economical and environmentally friendly “green material” with potential benefits in greenhouse gas emission reduction, soil performance improvement, and environmental restoration. Mixing biochar with clay and using it as a landfill cover can effectively reduce the escape of greenhouse gases into the air, which is important for environmental protection. It is suggested that biochar should be mixed with clay and used as a landfill covering layer. In this study, the shear strength was obtained by direct shear test, and the shear strength characteristics of biochar–clay mixture under the influence of different dry and wet cycles, biochar contents, and moisture conditions were studied. The results show that the shear strength of the biochar–clay mixture in the saturated state decreases with increasing wet and dry cycles, with shear strength decreases ranging from 6% to 19%. The cohesion and internal friction angles of the clays and mixtures show a decreasing trend under wet and dry cycles, with the cohesion and internal friction angles decreasing in the range of 2% to 16%. The shear stress–shear displacement curve for the biochar–clay mixture in the saturated state shows strain hardening after wet and dry cycles; the curve in the dry state shows strain softening with a distinct peak and a platform at the front end of the curve. The shear strength of clay in a dry state is larger than that of biochar–clay mixture and always larger than that of clay in a saturated state. The shear strength difference of the mixture between dry and saturated states is obviously smaller than that of pure clay. This paper, therefore, provides theoretical guidance for the application of biochar–clay mixtures to landfill covers.

This study compared and analyzed changes in the microclimate and thermal environment inside single-span greenhouses covered with a single layer of plastic film, polycarbonate (PC), and glass. The results of the experiment show that the PC-covered greenhouse was the most favorable for managing the nighttime heating effect during the cold season. However, the glass-covered greenhouse was found to be the most favorable for managing the cooling effect during the hot season. Although the plastic-covered greenhouse was inexpensive and easy to install, the air temperature inside varied significantly, and it was difficult to control its indoor environment. The thermal load leveling values showed that the PC-covered greenhouse had the lowest variation, confirming its superiority in terms of environmental control and energy savings. In terms of the overall heat transfer, heat was generally transferred from the interior to the exterior of the greenhouses. In the plastic-covered greenhouse, however, heat was transferred in the opposite direction at night due to the influence of radiant cooling. The occurrence of the minimum and maximum heat transfer values had a tendency similar to that of the occurrence of the minimum and maximum air temperatures inside the greenhouses.

Clubroot, caused by Plasmodiophora brassicae, is a destructive soil-borne disease significantly harming global Brassica crop production. This study employed the Williams and European Clubroot Differential (ECD) and Williams systems to identify the pathotypes of P. brassicae collected from Hangzhou City, Yuhang District and Quzhou City, Kaihua County in Zhejiang Province. Greenhouse and field trials were conducted to evaluate the effects of plastic film covering and four chemical agents on the growth parameters and clubroot severity of the Chinese cabbage cultivar ‘Granaat’. Potential treatment mechanisms on clubroot were explored through a qPCR analysis of the resting spore density and pH measurement of the soil. Furthermore, treatment with 1-napthaleneacetic acid (NAA), a synthetic auxin, was also evaluated for its potential role in suppressing clubroot. The results indicate that the pathotypes of P. brassicae in the two districts were P1, ECD20/31/12, and P3, ECD20/15/4. While an individual application of plastic film covering could not effectively control clubroot, calcium cyanamid, dazomet and ammonium bicarbonate demonstrated significant efficacy in its management. These three agents significantly reduced the resting spore density in the soil, with calcium cyanamid and ammonium bicarbonate also increasing soil alkalinity. Additionally, ammonium bicarbonate promotes lateral root development in ‘Granaat,’ helping infected plants access adequate water and nutrients. However, NAA exhibited no efficacy in clubroot control. Therefore, sustained lateral root development is crucial for effectively resisting P. brassicae invasion. Considering application costs and environmental friendliness, we propose the field application of ammonium bicarbonate as the optimal method for clubroot disease management in Zhejiang Province.

In order to meet the growing demand for food and achieve food security development goals, contemporary agriculture increasingly depends on plastic coverings such as agricultural plastic films. The remote sensing-based identification of these plastic films has gradually become a necessary tool for agricultural production management and soil pollution prevention. Addressing the challenges posed by the complex terrain and fragmented land parcels in karst mountainous regions, as well as the frequent presence of cloudy and foggy weather conditions, the extraction efficacy of mulching films is compromised. This study utilized a DJI Mavic 2 Pro UAV to capture visible light images in an area with complex terrain features such as peaks and valleys. A plastic film sample dataset was constructed, and the U-Net deep learning model parameters integrated into ArcGIS Pro were continuously modified and optimized to achieve precise plastic film identification. The results are as follows: (1) Sample quantity significantly affects recognition performance. When the sample size is 800, the accuracy of plastic film extraction notably improves, with area accuracy reaching 91%, a patch quantity accuracy of 96.38%, and an IOU and F1-score of 85.89% and 94.20%, respectively, compared to the precision achieved with a sample size of 300; (2) Different learning rates, batch sizes, and iteration numbers have a certain impact on the training effectiveness of the U-Net model. The most suitable model parameters improved the training effectiveness, with the highest training accuracy achieved at a learning rate of 0.001, a batch size of 10, and 25 iterations; (3) Comparative experiments with the Support Vector Machine (SVM) model validate the suitability of U-Net model parameters and sample datasets for precise identification in rugged terrains with fragmented spatial distribution, particularly in karst mountainous regions. This underscores the applicability of the U-Net model in recognizing plastic film coverings in karst mountainous regions, offering valuable insights for agricultural environmental health assessment and green planting management in farmlands.

Plastic films utilized as greenhouse coverings play a vital role in safeguarding plantations from diverse weather conditions like sunlight, rain, hail, and wind. It is essential for these films to preserve their properties even after extended exposure to sunlight and water, while also maintaining transparency to support the unhindered growth of plants. The purpose of the study was to compare the properties of three types of plastic films: low density polyethylene diffuse film, low density polyethylene clear film, and ethylene tetrafluoroethylene film, before and after their ageing in weather test chamber with xenon-arc light in the presence of moisture. Two distinct types of PE films were chosen based on their suitability for specific regions in Croatia, whereas ETFE film was chosen as a potential new material that is gaining popularity across various industries, including agriculture. The properties investigated were tensile properties, transmittance by spectral analysis, and viscoelastic properties by dynamic mechanical analysis. Also, untreated films and the ones exposed to artificial ageing were compared by means of Fourier-transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The administered tests revealed a certain level of property degradation due to ageing in all three films. However, none of the films showed a substantial level of deterioration, indicating their suitability as greenhouse coverings.

The spectral properties of selected UV-blocking and UV-transmitting covering materials were characterized by means of a UV–VIS spectroradiometer or a UV–VIS spectrometer to provide researchers and growers with guidelines for selecting suitable materials for use in studying the effects of ambient solar UV radiation on the production of tomatoes and other high-value crops in high tunnels. A survey was made of a wide range of plastic covering materials to identify commercially available products that had the desired characteristics of transmitting high levels of photosynthetically active radiation and of being stable under ambient solar UV radiation. The study was focused on evaluating films that either blocked or transmitted UV wavelengths below 380 nm to determine comparative growth, yield and market quality and to provide a tool for integrated pest management. Based on this survey, two contrasting covering materials of similar thickness (0.152 mm) and durability (4-year polyethylene), one a UV-blocking film and the other a UV-transmitting film, were selected and used to cover two high tunnels at Beltsville, MD. Spectroradiometric measurements were made to determine comparative spectral irradiance in these two high tunnels covered with these materials and under ambient solar UV radiation. Comparative measurements were also made of selected glass and plastic materials that have been used in UV exclusion studies.

Ornamental plant growers must be able to accurately assess production costs associated with woody liner stock to gain profit potential in a highly competitive industry. Fixed and variable cost inputs may not be intuitive or readily apparent to growers and may even differ between common types of production in the trade. To help liner producers identify profit-based price points for their woody ornamental liner stock, we modeled costs associated with producing familiar species and cultivars of a representative deciduous shade tree, a broadleaf evergreen, and a needle leaf evergreen liner. Production costs are projected down to individual plant units for each of the three most common liner production systems, including a field ground bed system, a polyhouse-covered (plant protection structure sheathed with one layer of 6-mil polyethylene film) ground bed system, and a polyhouse-covered container system. Production costs for individual plants varied due to the actual growing space available within each system. The field ground bed system offered greatest flexibility in crop planting density, with cost potentially distributed among the largest number of salable units. In addition to modeled costs, advantages and disadvantages of each liner cropping system are discussed.