Water Stress Index Detection Using a Low-Cost Infrared Sensor and Excess Green Image Processing.

Precision Irrigation (PI) is a promising technique for monitoring and controlling water use that allows for meeting crop water requirements based on site-specific data. However, implementing the PI needs precise data on water evapotranspiration. The detection and monitoring of crop water stress can be achieved by several methods, one of the most interesting being the use of infra-red (IR) thermometry combined with the estimate of the Crop Water Stress Index (CWSI). However, conventional IR equipment is expensive, so the objective of this paper is to present the development of a new low-cost water stress detection system using TL indices obtained by crossing the responses of infrared sensors with image processing. The results demonstrated that it is possible to use low-cost IR sensors with a directional Field of Vision (FoV) to measure plant temperature, generate thermal maps, and identify water stress conditions. The Leaf Temperature Maps, generated by the IR sensor readings of the plant segmentation in the RGB image, were validated by thermal images. Furthermore, the estimated CWSI is consistent with the literature results.

Mechanical properties of lettuce (Lactuca sativa L. ) for horticultural machinery design

Currently, there is a growing need to develop machines that replace human work efficiently and effectively in horticulture with the same sensibility of the human hand, since horticultural foods are notably very fragile to handle and process, especially considering machinery and systems. This work aimed to determine the mechanical properties of lettuce (Lactuca sativa L.) variety Crispa. For that, two methodologies were used in the field of material engineering: one specific for polymers and composites - the standard ASTM D3039 - Standard test method for tensile properties of polymer matrix composite materials (ASTM, 2002a) and the other specific for plastic films - the ASTM 882 - Standard test method for tensile properties of thin plastic sheeting (ASTM, 2002b). The tests were adapted for lettuce samples. The mechanical properties for the leaf and stem of head lettuce (var. Crispa) were obtained with appropriate statistical rigor, which can be considered valid initial estimates for dimensioning mechanisms and systems of machines for horticultural works specialized in lettuce. These properties provide fundamental engineering parameters to design machine elements that interact with biological materials, allowing to develop devices that generate minor damage to biological structures in lettuce.