INNOVATIVE PRACTICAL LESSON TO ANALYZE SOLAR TRANSMITTANCE OF GLASSHOUSES IN AGRICULTURAL ENGINEERING DEGREE

Nowadays the use and interest of technologies of information and communication (TICs) are increasing. In this regard, TICs are of paramount importance for university students, particularly those from technical degrees (i.e. engineering).

The present work is a pioneer practical lesson designed for agricultural engineering pre-graduates at Universitat Politècnica de València (UPV), as a way to acquire a comprehensive training and competences in:
i) physical properties of the light,
ii) effect of glasshouse coverings and
iii) application of TICs and specific tools. Nevertheless, it can be extended to students of master, which are attending subjects related to applied physics or optical properties of materials.

Glasshouses in Mediterranean areas are mainly used for experimental or nursery purposes and the production of high value ornamentals and vegetables. In addition, glasshouses may be covered by dust and other particles in these areas as rainfalls are relatively scarce. As a consequence, glasshouses transparency and, by extension, the quality of irradiance spectrum and therefore photosynthetic process by plants may be affected.

The lesson will be divided into two sessions. Firstly, following a flipped teaching methodology, students will be asked to revise basic concepts about spectral irradiance, spectral regions affecting photosynthesis, and the most commonly used parameters, such as Photosynthetic Photon Flux Density (PPFD, µmol/m²s) before a theoretical session. Additionally, the sensor used to measure PPFD, an Asensetek Lighting Passport Pro handheld ALP-01 spectrometer, which covers a spectral range from 380 to 780 nm, will be showed and explained to students. This spectrophotometer compares the photometric parameters of different lighting sources. Also, all the information can be transferred to an Apple ® or Android ® Smartphone, via Bluetooh, through official APPs that can be download freely by students. Therefore, in this session the students will learn how it works and the main factors to be considered when measuring solar irradiance (position of the dosimeter, optimal weather conditions...). The final session will be devoted to the practice and the application of the acquired knowledge. The students will compare the transmittance of 4-mm thick glass from Venlo-type glasshouses in two conditions:
i) not washed for one year (dirty glass),
ii) recently washed and
iii) direct sunlight exposure (control, out of the glasshouse).