Greenhouse Environmental Parameters Research Articles

Research on Control System of Energy-Saving Greenhouse

Energy-saving and environmental protection has become the theme of the 21st century. Greenhouse is an energy-intensive industries. Every year, 35% of energy consumption on agricultural production is used for greenhouse heating in the world, which accounts for 15-40% of the cost of greenhouse production. For improving energy efficiency and protecting the environment, the reasonable control of greenhouse environmental parameters is significant. The design of solar greenhouse real-time environment monitoring and automatic control system is based on 8051 single-chip in the thesis. The temperature and humidity signal are obtained from DS18B20 digital temperature sensor and IH3605 humidity sensor. When the greenhouse temperature exceeds the set temperature, the device can be started by perform timely processing, then the user can read LED digital display temperature and humidity values.

Design and Implementation of the Greenhouse Environmental Monitoring System Based on JN5148

This paper designs a greenhouse environment system based on JN5148. The system uses JN5148 as the main module, setting up the wireless network with JenNet protocol stack. This system realizes true-time monitoring of environment factors which include air temperature and humidity, light intensity and CO2 concentration etc, rolling machines and pumps remote control. Test results show that system network operates stably, data acquisition precision is high, notes consume low and feedback control is accurate, and meets the application requirements of the greenhouse environment parameters monitoring.

Short- and long-term stomatal responses to fluctuations in environment in southern European greenhouses

Stomatal behaviour in cucumber (Cucumis sativus L.) was analysed and modelled as a function of different greenhouse environmental parameters, under variable summer conditions. Solar radiation was the main regulating factor. During the day, large atmospheric vapour pressure deficit increased transpiration which was followed by a reduction in stomatal aperture, suggesting the presence of a feedback response to water stress. However, stomatal behaviour was more sensitive to high atmospheric vapour pressure deficit when this was accompanied by a rapid decrease of solar radiation. The response to the difference between leaf and air temperature was also influenced by air vapour pressure deficit and duration of plant exposure to high evaporative demand. Calculation of the crop water stress index showed that the air vapour pressure deficit of 1 kPa used in the control treatment probably caused water stress and induced some hardening, a necessary condition for adaptation to summer climate in southern Europe. The importance of the interaction between climatic parameters and plant response in greenhouse environmental management is analysed. Classical models of stomatal resistance are also discussed.

Improvements in Automatic Irrigation of Peat-grown Greenhouse Tomatoes

An automatic irrigation system was designed for use on green-house tomatoes growing in peat-based substrates. This system uses electronic tensiometers to monitor continuously substrate matric potential (SMP) in peat-bags. The system also uses the Penman equation to evaluate potential evapotranspiration (PET) through the acquisition of many greenhouse environmental parameters. Through a series of linear equations, estimates of PET are used in a computer-controller system to vary the electrical conductivity (EC) of irrigated nutrient solutions, as well as SMP setpoints at which irrigations are started. Such modifications to current irrigation management systems may improve fruit quality and reduce the risk of water stress during periods of high PET by irrigating more frequently with less-concentrated nutrient solutions. Conversely, during periods of low PET, irrigation is less frequent with more-concentrated nutrient solutions. Although no differences were found in fruit number or overall yield using variable nutrient solution EC, plant fresh weight was higher in those treatments. It is concluded that an integrated tensiometer-PET system may give increased precision to irrigation management and the control of crop growth in the greenhouse.

Greenhouse environment and epidemiology of grey mould of container-grown Douglas-fir seedlings

The environmental parameters associated with grey mould, Botrytiscinerea Fr.: Nocca & Balbis, on container-grown Douglas-fir, Pseudotsugamenziesii (Mirb.) Franco, were studied in a plastic-covered greenhouse and a fibreglass-covered greenhouse near Victoria, British Columbia. Disease losses and numbers of B. cinerea spores were much higher in the fibreglass-covered house, where seedlings were taller and more succulent because the fibreglass reduced light intensities. From July to October the length of time when the combination of temperature and relative humidity that favours B. cinerea spore germination and infection was 14.5 times greater in the fibreglass-covered than in the plastic-covered house. Conditions beneath the seedling canopy that enhance the disease were more prevalent in July and August than in the autumn when the disease becomes evident, suggesting that earlier application of preventive fungicides may benefit disease control. Grey mould inoculum originated from outside the greenhouses, but once the disease was established on the seedlings, numbers of spores within the houses exceeded those outside. Airborne spore numbers both outside and within the greenhouses were highest during the day. Numbers of spores within the houses peaked when the irrigation system was on; this is ascribed to the mechanical effect of the irrigation water on spore dispersal rather than to changes in greenhouse environmental parameters.