# A Critical Review of the Status of Current Greenhouse Technology in China and Development Prospects
## 5 Research on Chinese Greenhouse Technology
### Automation  
At present, the most common automated systems in modern greenhouses in China mainly include intelligent water and fertilizer supply integration, air temperature control, and ventilation systems. Carbon dioxide is important for plant photosynthesis and it affects the yield of vegetables produced in greenhouses. By adding carbon dioxide sensors and carbon dioxide supply to greenhouses, the carbon dioxide supply can be controlled within a broad range of up to 4000 ppm [48]. Intelligent water-fertilization includes an intelligent irrigation system and an intelligent fertilizer system. Soil moisture sensors monitor the soil moisture content, and drip irrigation is then controlled accordingly. The fertilizer system mainly consists of a venturi, a mother tank, an acid tank, and an alkaline solution tank, and the venturi fertilizer applicator draws the solution from the other tanks into the mixing tank for fertilizer application. Taking growing strawberries as an example, traditional strawberry planting is not only time-consuming and labor-intensive but also prone to uneven strawberry growth. As shown in Table 2, the use of an intelligent water-fertil integrated system is better than traditional planting modes in all aspects [49]. [PERSON] [50] recently designed an intelligent temperature control system for greenhouses that uses the input of several sensors, such as solar radiation, air temperature and humidity, CO2 concentration, and soil moisture sensors, to make appropriate decisions in terms of controlling the temperature inside the greenhouse by activating several pieces of equipment, such as fan and pad systems or heating systems accordingly [50]. Although there is continuous progress in China in terms of researching and implementing automated control systems and artificial intelligence, there is still a gap between China and other developed countries [51]. One major difficulty is due to the fact that greenhouse cultivation is still dominated by plastic-covered greenhouses, where automation is more difficult to achieve than in modern glass-covered greenhouses. Many trials in applied research have been carried out to narrow this gap by automating most of the environmental monitoring and control systems in greenhouses, and this gap is gradually narrowing. [PERSON] et al. [52] proposed a light environment control system for solar greenhouses based on the opening of rolling shutters (ORS), which controls the light environment of greenhouses by operating the shutters under different conditions. The experimental results showed that the ORS control system was able to regulate the greenhouse light environment to the desired value and effectively regulate the light level as needed. [PERSON] et al. [53] studied and designed a multi-energy supply system for the intelligent control systems of a  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Cropping Patterns**} & **Quality of Individual** & **Soluble Sugar** & **Vitamin C** & **Glucosniolate** & **Water Utilization** & **Fertilizer Utilization (\%)** \\  & **Fruits (g)** & **(mg\(\cdot\)g\({}^{-1}\))** & **(mg\(\cdot\)(100 g\({}^{-1}\)))** & **Ratio (\%)** & **(kg\(\cdot\)m\({}^{-3}\))** & **Utilization (\%)** \\ \hline Intelligent irrigation-fertilization & \multirow{2}{*}{\(11.60\pm 0.15\) integration} & \multirow{2}{*}{\(7.35\pm 0.21\)} & \multirow{2}{*}{\(167.86\pm 4.47\)} & \multirow{2}{*}{\(5.55\pm 0.37\)} & \multirow{2}{*}{\(6.78\pm 0.35\)} & \multirow{2}{*}{\(12.89\pm 0.62\)} \\ \cline{1-1} \cline{6-6}  
greenhouse with an improved adaptive genetic algorithm. The experimental results show that through the intelligent control of greenhouses, the deviation in the air temperature settings is less than 0.5 \({}^{\circ}\)C, and the deviation in the air relative humidity settings is less than 1%, while the maximum deviation value of the carbon dioxide concentration variation is less than 2.5%. [PERSON] et al.