With the random discharging of industrial and agricultural wastewater, a large amount of cadmium (Cd) has accumulated in the soil, which seriously affects the growth of crops and people’s food safety. In this study, alfalfa was used as the material for studying the effects of the inoculation of Piriformospora indica (P. indica) on photosynthesis, osmoregulatory substances, and antioxidant enzymes of alfalfa seedlings at different Cd concentrations (0, 5, 10, 30, 50, and 100 mg/L) through hydroponic experiments. The results showed that with the increase in Cd concentration, the chlorophyll content, net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) of alfalfa all decreased gradually, while the intercellular CO₂ concentration (Ci) decreased at first and then increased. However, compared with non-inoculated control plants, the inoculation of P. indica improved the photosynthesis (41.97%) of alfalfa under Cd stress, increased the chlorophyll content (43.70%), and significantly increased the contents of proline (29.86%), soluble proteins (38.54%), and antioxidant enzyme activities. It was concluded that P. indica alleviates the negative effects of Cd on alfalfa plants to some extent. This is because P. indica can resist Cd stress and improve plant growth in cadmium-contaminated agricultural soil by alleviating membrane peroxidation damage, regulating osmotic regulatory substances, and enhancing enzyme activity to improve the antioxidant defense system. Thus, P. indica can be considered a biological fertilizer for improving plant growth and physiology in soils contaminated with cadmium.

This paper proposes a spatiotemporal fusion-based evapotranspiration inversion model (OL-SS) for grassland areas on the GEE platform. The model uses the OL processing strategy, with Landsat imagery being used as fine-resolution images and MCD43A4 imagery as coarse-resolution images, combined with GEE’s spatiotemporal fusion technology to generate 30 m resolution images. It then estimates the daily evapotranspiration of grasslands using the constant evaporation ratio method. The model was validated in the Xilin Gol League, Inner Mongolia, for grassland evapotranspiration inversion during the summer of 2015. The results show the following: 1. the OL-SS model can efficiently generate good spatiotemporal fusion results, but the fusion effect is poorer in some images due to cloud cover; 2. compared with the measured data from flux stations in grassland areas, the evapotranspiration inversion results show a good fit. The model demonstrates strong performance in grassland evapotranspiration monitoring and is suitable for the rapid estimation of daily evapotranspiration in certain grassland regions.