In order to clarify the temporal and spatial changes in the internal photothermal environment in an open-field agrivoltaic system (OAVS), this paper took the OAVS in eastern China as the research object and divided the internal area into the southern area, middle area and northern area, according to the spatial structure. Further, a photothermal environment test was conducted in the above three areas in the summer and winter. The results showed that the summer average daylight rate (R_m-avg) in the middle area was 66.6%, while the R_m-avg in the other two areas was about 20%, with no significant difference. In the winter, the light environment in the southern area was slightly better, and the R_m-avg in the above three areas was 26.4%, 24.7% and 19.7%, respectively. On the whole, the relationship between the thermal environmental factors and the solar radiation intensity was consistent. Further, a 3D model of an OAVS was established using Autodesk Ecotect Analysis 2011, and the internal light environment was simulated. Compared with the measured values, the relative error was less than 10%, which verified the reliability of the OAVS model. Then, the model was used to reveal the temporal and spatial changes in the light environment of the OAVS. The simulation results showed that the daylighting rate in the summer from the ground to the height of the fig canopy inside the system was 20.7% to 61.5%. In the winter, the daylighting rate from the ground to the height of the fig canopy inside the system was 17.7% to 36.4%. The effectiveness of the OAVS in reducing the level of solar radiation intensity depended on the time of day and the angle of the sun. At the spatial scale, due to the strong consumption of light by photovoltaic panels, there was a strong horizontal and vertical light environment gradient inside the system. In conclusion, the photothermal environment research of an OAVS based on Autodesk Ecotect Analysis 2011 can not only provide a basis for agricultural production and structural design such as span, height and the laying density of PV panels, but also expand its application to regions with different latitudes and longitudes and specific climates.

Continuous cropping can lead to an excessive accumulation of nitrate in facility-cultured soil. Excessive accumulation of nitrate gradually becomes the main reason for crop failure in vegetables and endangers human health. Therefore, the exploration of effective measures to decrease abundant nitrate accumulation in Chinese flowering cabbage is indispensable. In this study, a kind of plant growth regulator, fulvic acid (FA), was used to study its positive effect on alleviating the growth inhibition induced by excessive Ca(NO₃)₂ in Chinese flowering cabbage. Meanwhile, we conducted hydroponic cultivation and measured the growth indices, photosynthetic and oxidation-reduction characteristics of Chinese flowering cabbage with different treatments. After determining the optimal treatment concentration, we mainly designed four treatment groups, including Con, FA, Ca(NO₃)₂ and FA + Ca(NO₃)₂ cotreatment, to explore the regulatory mechanism by which FA alleviates Ca(NO₃)₂ stress in Chinese flowering cabbage. The results showed that FA can effectively alleviate the inhibitory effect of excessive Ca(NO₃)₂ on the growth of Chinese flowering cabbage seedlings. FA recovered the photosynthetic capacity of seedlings under Ca(NO₃)₂ stress. In addition, FA depressed the accumulation of O^2·−, H₂O₂, malondialdehyde (MDA) and relative electrical conductivity, but increased the activity of antioxidant enzymes, including SOD, POD, CAT and APX, which finally enhanced the stress resistance of Chinese flowering cabbage to Ca(NO₃)₂. The expression of nitrate-related transporters, BcNRT1.1 and BcNRT1.5, was depressed by FA, which inhibited redundant nitrate absorption and restricted more nitrate from being stored in the roots instead of being transferred to the shoot. Ultimately, nitrate accumulation in the edible part was reduced in Chinese flowering cabbage seedlings. In general, exogenous FA may alleviate nitrate stress by improving oxidation resistance, photosynthetic capacity and redundant Ca(NO₃)₂ accumulation in Chinese flowering cabbage.

Tracking agrivoltaic (TAV) systems represent a significant form of agrivoltaics, which optimize solar energy capture through the dynamic adjustment of photovoltaic (PV) panel tilt angles. However, there is limited research on the effects of TAV systems on the three-dimensional spatial distribution of the light environment within PV arrays and their impacts on agricultural production. Therefore, a comparative experiment was conducted between wheat production under a TAV system and traditional open-field cultivation. Solar radiation intensity sensors were deployed to continuously monitor the dynamic changes in solar radiation under and between the PV panels throughout the entire growth period. Simultaneously, a light environment model for the TAV system was constructed, and the photosynthetic parameters of wheat leaves, as well as yield, were measured. The results indicated that the light environment within the system exhibited significant gradient attenuation, with average light capture rates of 43.2% and 46.1% for the inter-panel and under-panel measurement points, respectively. The model results confirmed that the synergistic adjustment of panel tilt angle and solar altitude angle significantly affected the shading effects, leading to notable spatiotemporal heterogeneity in the light environment during the winter solstice, spring equinox, and summer solstice. This heterogeneity showed as regular variations in shadows and radiation, collectively forming a dynamic light–thermal environment that influences crop growth. Wheat yields under and between the panels decreased by 11.5% and 6.6%, respectively, compared to the open-field control, with yields of 4625.9 kg·hm⁻² and 4883.6 kg·hm⁻². Additionally, the photosynthetic characteristics of the leaves effectively reflected the yield differences. Overall, the comprehensive benefit assessment demonstrates that the TAV system can effectively mitigate the reduction in wheat yield in PV farmlands. This study provides a theoretical basis for optimizing the light environment in AV systems.

Effects of the air ducts layout in the back wall on the heat transfer and storage characteristics of active heat storage back wall of solar greenhouse