COMECYT, Universidad Politécnica de Otzolotepec, Otzolotepec, Mexico.
Universidad Politécnica de Otzolotepec, Otzolotepec, Mexico.
Int J Radiat Biol. 2024;100(3):445-452. doi: 10.1080/09553002.2023.2295299. Epub 2024 Jan 3.
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.
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 mm), respectively. The leaves' photosynthesis and transpiration rates were measured using an LI-6400XT Portable Photosynthesis System.
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.
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.
评估超声（US）辐照对水生蔺叶片结构损伤和光合作用及蒸腾速率的变化，寻找控制这种杂草的环保方法。
从墨西哥城的霍奇米尔科水道中提取水生蔺植物。将一部分植物选作照射组，其余的作为对照组。照射组植物在中午和 25°C 室温下，用 17 kHz 频率和 30 W×4 输出功率的 US 照射 2 小时。结构分析使用 MOTICAM 1 数字相机（800×600 像素），集成到 MOTIC PSM-1000 光学显微镜中，并使用 Motic Images Plus 2.0 ML 软件编辑。通过将总气孔密度和受损气孔密度分别除以视场面积（67917mm）来确定总气孔密度和受损气孔密度。使用 LI-6400XT 便携式光合作用系统测量叶片的光合作用和蒸腾速率。
观察到气孔和表皮细胞明显受损，发现受损和总气孔密度的比值随时间（天数）的函数呈指数增长，用 Box-Lucas 方程描述，饱和值接近 1，零天（即照射后立即）时受损气孔密度的最大变化率最高，随着天数的增加而降低。蒸腾速率在照射后第一小时内突然增加，达到照射前值的 36%。然后在接下来的 6 天内迅速下降，在第 21 天下降到照射前值的 79.9%。光合作用速率表现出类似的行为，最大增量为 37.7%，照射前值最低下降 73.6%。
超声辐照水生蔺叶片结构气孔损伤的结果与气孔保卫细胞机械操作的过度超声刺激一致，这种刺激导致在照射后第一小时内测量的光合作用和蒸腾速率显著增加。最初的高蒸发可能会改变水势梯度，在木质部中产生可能导致其导管栓塞的张力。木质部导水率的丧失或水力失效与照射后第一小时突然升高后水生蔺叶片光合作用和蒸腾速率的显著下降是一致的。
