Stomata damage, photosynthesis, and transpiration evaluation of aquatic lirium after ultrasound irradiation.

PURPOSE: Evaluate the structural damage and the changes in the photosynthesis and transpiration rates of aquatic lirium leaves caused by ultrasound (US) irradiation in search of environmentally friendly methodologies for the control of this weed. MATERIALS AND METHODS: Aquatic lirium plants were extracted from Xochimilco water canals in Mexico City. A part of the group of plants was selected for irradiation, and the rest formed the control group. The irradiation plants group was exposed to US irradiation of 17 kHz frequency and 30 W × 4 output power for 2 h, at noon and 25 °C room temperature. The structural analysis was done with a MOTICAM 1 digital camera, 800 × 600 pixels, incorporated into the MOTIC PSM-1000 optical microscope and edited with Motic Images Plus 2.0 ML software. The total stomata density and the damaged stomata density were determined by dividing the numbers of total and damaged stomata by the visual field area (67,917 mm2), respectively. The leaves' photosynthesis and transpiration rates were measured using an LI-6400XT Portable Photosynthesis System. RESULTS: Significant damage was observed in the stomata and epidermal cells, finding that the average ratio between the damaged and total stomata densities as a function of time (days) showed an exponential increase described by a Box-Lucas equation with a saturation value near unity and a maximum rate of change of the density of damaged stomata on zero-day (immediately after irradiation), decreasing as the days go by. The transpiration rate showed a sudden increase during the first hour after irradiation, reaching a maximum of 36% of its value before irradiation. It then quickly fell during the next 6 days and more slowly until the 21st day, decreasing 79.9% of its value before irradiation. The photosynthetic rate showed similar behavior with a 37.7% maximum increment and a 73.6% minimum decrease of its value before irradiation. CONCLUSIONS: The results of structural stomata damage on the ultrasound-irradiated aquatic lirium leaves are consistent with an excessive ultrasound stimulation on stomata's mechanical operation by guard cells that produce the measured significant increase of the photosynthetic and transpiration rates during the first hour after irradiation. The initial high evaporation could alter the water potential gradient, with a possible generation of tensions in the xylem that could cause embolism in their conduits. The loss of xylem conductivity or hydraulic failure would be consistent with the observed significant fall in the photosynthesis and transpiration rates of the aquatic lirium leaves after its sudden rise in the first hour after irradiation.

Ultrasound irradiation effect on photosynthesis and transpiration of aquatic lirium plants.

PURPOSE: To find possible causes of the photobaric response decrease in photoacoustic measurements on Aquatic Lirium plants after ultrasonic irradiations reported elsewhere contributing to understanding the effect of ultrasonic irradiation on them and searching for environmentally friendly methodologies to control this weed. MATERIALS AND METHODS: The plants were extracted from their natural habitat in Xochimilco water canals, Mexico City. The irradiations on the plants were carried out to 2 hours exposure time, 17 kHz frequency, and 30 W x 4 output power. We used the photoacoustic spectroscopy technique at room temperature in the range of 400-750 nm to analyze the optical absorption response of photosynthetic pigments before and after ultrasonic irradiations. To monitor the leave transpiration rate, we used an LI-COR 6400XT portable system, expressed in units of mols H2O per second per unit area of the leaf surface. RESULTS: We obtained a significant decrease of the chlorophylls bands amplitude in the photoacoustic spectroscopy spectra and a drastic reduction in the leaves transpiration rate of irradiated plants that depends on the time elapsed after irradiation. Remarkable physical changes in the leaves and petioles of the irradiated plants were observed with the naked eye. CONCLUSIONS: A significantly decreasing photosynthesis and transpiration in the leaves of the irradiated lirium plants were obtained. Together with the observed physical changes in the leaves and petioles, these results suggest an alteration in the water transport and the overall gas exchange mechanisms affecting the irradiated leaves' transpiration and photosynthesis processes that agree with the photobaric response decrease reported elsewhere. Due to the fundamental role of stomata in these mechanisms, it is suggested, as a possible cause, that the ultrasonic-induced disruption of stomata's mechanical operation by guard cells prevents them from performing their function normally. A hypothesis to be confirmed in future studies, for which a line of action is proposed.

System for Face Recognition under Different Facial Expressions Using a New Associative Hybrid Model Amαß-KNN for People with Visual Impairment or Prosopagnosia.

Face recognition is a natural skill that a child performs from the first days of life; unfortunately, there are people with visual or neurological problems that prevent the individual from performing the process visually. This work describes a system that integrates Artificial Intelligence which learns the face of the people with whom the user interacts daily. During the study we propose a new hybrid model of Alpha-Beta Associative memories (Amαß) with Correlation Matrix (CM) and K-Nearest Neighbors (KNN), where the Amαß-CMKNN was trained with characteristic biometric vectors generated from images of faces from people who present different facial expressions such as happiness, surprise, anger and sadness. To test the performance of the hybrid model, two experiments that differ in the selection of parameters that characterize the face are conducted. The performance of the proposed model was tested in the databases CK+, CAS-PEAL-R1 and Face-MECS (own), which test the Amαß-CMKNN with faces of subjects of both sexes, different races, facial expressions, poses and environmental conditions. The hybrid model was able to remember 100% of all the faces learned during their training, while in the test in which faces are presented that have variations with respect to those learned the results range from 95.05% in controlled environments and 86.48% in real environments using the proposed integrated system.