As the fourth major staple crop after rice, wheat and corn, potato is of great significance for ensuring the national food security. In order to explore the response characteristics of potato (Solanum tuberosum L.) yield, leaf photosynthetic physiology, dry matter accumulation characteristics to water stress in the semi-arid region of the Loess Plateau, the soil water stress experiment was conducted in 2021 by using the main potato variety “Xindaping” as the test material. The soil water was controlled during the critical period of tuber enlargement (August). Field water capacity was set at 40%±5% (moderate water stress, T1 treatment) and 55%±5% (mild water stress, T2 treatment), and 75%±5% (full water treatment, T3) was used as the control for analysis. The results show that under water stress, the maximum tuber weight per plant, tuber weight per plant and yield all decreased, the number of tubers decreased, the weight and the number of pellet potato increased significantly (P<0.05), and compared with T3 the yield of potato under T1 and T2 treatments decreased by 30% and 13%, respectively. The net photosynthetic rate (P_n), stomatal conductance (G_s) and intercellular CO₂ concentration (C_i) of potato leaves decreased significantly, among them the G_s decreased by 59%, and the water use efficiency (WUE) of T1 treatment was 31% higher than that of T3. In the weak light area, the effect of moderate and mild water stress on P_n is not obvious (P>0.05), when the light intensity was higher than 300 μmol·m^-2·s^-1, the differences between treatments increased, and P_n under T1 and T2 treatments decreased by 42% and 32% on average compared with T3. Under the influence of water stress, the maximum net photosynthetic rate (P_nmax), light compensation point (LCP) and dark respiration rate (R_d) decreased significantly (P<0.05), and light saturation point (LSP) under mild water stress was the highest (893.32 μmol·m^-2·s^-1). The range of available photosynthetically active radiation (PAR) of leaves decreased under moderate water stress, and the ability to use strong light decreased. The dry matter weight of roots, stems, leaves and petioles decreased under water stress, and under moderate water stress, the petiole decreased the most (63%), followed by leaves (57%) and roots (50%). This study can provide theoretical basis for potato drought damage assessment and soil water efficient utilization in semi-arid area of Loess Plateau.

Drought is a major meteorological disaster with the highest frequency, the longest duration and the widest scope of harm in the world today, which has a huge and extensive impact on agriculture, ecology, social development and national economy all over the world. The drought is an important factor affecting agricultural production which determines the stability of crop production, further relates to the national food security. China is a large agricultural country, and also is a country with frequent drought disaster. Therefore, to improve the monitoring, forecasting and warning level of agricultural drought disaster, it is necessary to deeply understand its formation, influence characteristics, drought intensity, severity and physiological process and mechanism of crop victimization. It is also an important scientific problem to reduce and prevent drought disaster losses and improve national food security production. This paper comprehensively reviews the recent internal and overseas research progress of agricultural drought with different degrees and its impact on crop production, and explores the influence characteristics and mechanism of drought from the aspects of crop morphology, physiology, cellular and molecular levels, etc. The main indicators, indexes, methods and early warning systems in current agricultural drought monitoring are reviewed around food production to cope effectively agriculture drought. According to the new characteristics of agricultural sustainable development and drought, the current situation of drought disaster prevention and mitigation and agricultural drought coping are discussed. A series of drought coping measures both adaptation and mitigation are emphasized. On this basis, combining with the needs of national, regional and industrial development, the paper puts forward the important scientific problems, research countermeasures and the prospect of discipline development which should be emphasized in the future.

 Based on the wind lidar observation data and 12 wind shear events reported by pilots at Lanzhou Zhongchuan airport from July to November 2020, the performance and effectivity of two lidarbased lowlevel wind shear alerting algorithms were investigated. One algorithm is the regional divergence algorithm (RDA), and another is the combinational algorithm of single ramp and double ramps detection. The IRIS algorithm, the default algorithm in the lidar, was used as a reference. The conclusions are as follows: (1) RDA and ramp detection algorithm had better ability in alerting wind shear events under the convection weather or downward momentum weather conditions. However, they had a poor performance on identification of wind shear events under turbulent conditions. (2) Compared with ramp detection algorithm, RDA uses multiradial directions to reconstruct headwind profile, and consequently it can provide some temporal and spatial evolution information of radial velocities along the runway and its extension line, which is conducive to identification and alerting of wind shear events ahead of time. (3) The alerting results on 12 wind shear events indicated that RDA was superior to ramp detection algorithm and IRIS algorithm.

Based on the hourly precipitation data at 24 meteorological stations of Shandong Peninsula from May to October during 1985-2016 and 6-hour reanalysis data of ECMWF from May to October during 2010-2016, the diurnal variation characteristics of precipitation in summer half year were analyzed in detail. The results are as follows: (1) The diurnal distributions of precipitation, precipitation frequency and precipitation intensity appeared double peaks pattern in Shandong Peninsula in summer half year, and the peaks appeared from 02:00 BST to 05:00 BST and at about 15:00 BST, respectively. The peak of precipitation and precipitation frequency in early morning was obviously greater than that in the afternoon. (2) The contribution of long-duration precipitation to total precipitation was greater than that of short-duration precipitation in summer half year in Shandong Peninsula. The peak of the former occurred from 03:00 BST to 06:00 BST, while the main peak of the latter occurred from 15:00 BST to 18:00 BST, which indicated that they had dominant impacts on the peak of total precipitation in early morning and afternoon, respectively. (3) The contribution of light rain to total precipitation frequency was the maximum at any time during a day, and the frequency of light rain accounted for nearly half of total precipitation frequency. However, the precipitation intensity of heavy rain and torrential rain was significantly stronger than that of light rain and moderate rain, they had greater contribution to total precipitation, so the total precipitation was mainly due to heavy rain and torrential rain.

In order to study the effect of warming on field water characteristics of spring wheat，the field experiments that temperature was increased by an infrared radiator were designed at Dingxi experiment station in semi － arid area of the Loess Plateau in central Gansu． The results showed that with the increase of temperature，leaf water potential was lowered． Compared with no warming，warming of 1． 0 ℃ and 2． 0 ℃ reduced daily average leaf water potential by 2． 61% and 4． 45%，respectively． Soil water potential increased with increase of soil depth gradually． With the increase of temperature，soil water potential at different soil depth showed a decreasing trend， the higher temperature was，the greater decline of soil water potential was． There was negative correlation between warming and soil water content． Warming significantly decreased soil water storage of spring wheat，and increased evapotranspiration． Under the conditions of warming 2 ℃，irrigation increased the total storage capacity of soil，especially after jointing stage． Soil water consumption amount increased with the increase of temperature ( 0 － 100 cm) ，while the variation tendency of soil water consumption amount was not obvious ( 100 － 160 cm) ． When temperature was increased by 2 ℃，soil water consumption amount of wet treatment was higher than that of the normal water supply and drought treatment for 0 － 160 cm soil depth．

Abstract: The reflectance spectra were measured of some featured crops and typical vegetation with the ASD Handheld FieldSpec spectrometer
FR2500 in Gansu province． By the computer programming technology，the spectra database of typical ground objects in northwest
China was set up． This paper mainly introduces spectrum data collection，the establishment course of database system，application
and problems of database．