Changes in global climate and precipitation patterns have exacerbated the existing uneven distribution of water, causing many plants to face the alternate situation of drought and water flooding. We studied the growth and physiological response of the wetland plant Artemisia selengensis to drought and rehydration. In this study, Artemisia selengensis seedlings were subjected to 32.89% (SD), 47.36 % (MD), 60.97% (MID), and 87.18 % (CK) field water holding capacity for 70 days, followed by 14 days of rehydration. The results showed that drought inhibited the increase of plant height, basal diameter, and biomass accumulation under SD and MD, but the root shoot ratio (R/S) increased. Drought stress also decreased the content of total chlorophyll (Chl), chlorophyll a (Chl-a), chlorophyll b (Chl-b), and carotenoid (Car). Soluble sugar (SS) and proline (Pro) were accumulated rapidly under drought, and the relative water content (RWC) of leaves was kept at a high level of 80%. After rehydration, the plant height, basal diameter, biomass, and R/S ratio could not be recovered under SD and MD, but these indicators were completely recovered under MID. The RWC, Chl, Chl-a, Chl-b, Car, and osmotic substances were partially or completely recovered. In conclusion, Artemisia selengensis not only can improve drought resistance by increasing the R/S ratio and osmotic substances but also adopt the compensatory mechanism during rehydration. It is predictable that A. selengensis may benefit from possible future aridification of wetlands and expand population distribution.

With the help of artificial intelligence technology, the unmanned aerial vehicle (UAV) industry is booming. In the civilian field, a series of fully functional UAV products have emerged one after another, giving birth to a huge industrial chain. To strengthen the UAV market supervision, many countries have introduced a series of standards to regulate UAV products, but they have not yet developed a high-precision positioning system for UAV quality inspection. In this paper, we proposed a high-precision UAV positioning method based on ultra-wideband (UWB) technology. We analyzed the algorithm, base station layout, and clock synchronization to improve the accuracy of the UWB positioning system and established a high-precision UAV trajectory tracking and measurement system based on UWB technology, realizing real-time high-precision positioning of UAVs. Based on the Chan algorithm, we analyzed the base station layout method in combination with the system construction site and proposed a new delay calibration method between positioning base stations. Experimental results show that we have achieved a horizontal accuracy of under 0.1 m and a vertical accuracy of under 0.15 m in a space of 120 m × 60 m × 40 m.

Typha orientalis is an important aquatic plant and is sensitive to the water level. Here, the ecological amplitude of T. orientalis under different water levels was determined by measuring its growth and physiological indices. Results showed that: (1) The growth characteristics of T. orientalis showed quadratic relationships with water level, plant height, withered leaf rate, base diameter, leaf length, leaf width, leaf area, and biomass. Each of these growth characteristics showed an increasing then decreasing trend as water level was increased. (2) Most physiological characteristics of T. orientalis (Chla, Chlb, Car, SOD activity, CAT activity, soluble protein content, and root activity) also showed quadratic relationships (increasing then decreasing) with an increase in water level. Conversely, POD activity and MDA content showed an inverted quadratic relationship, as they decreased then increased as water level increased. (3) We determined an optimum water level for T. orientalis growth of 14.43 cm, a range of limiting water levels for T. orientalis growth of À52 cm to 74.93 cm, with the range of À19.75 to 42.55 cm being the most suitable for growth. Water levels in excess of 74.93 cm and below À52 cm cannot facilitate the normal growth and development of T. orientalis.

No abstract