As the impact of climate warming on agro-ecosystems intensifies, the arid and semi-arid crops in the northwest, where water resources are extremely scarce, will face major challenges. In this paper, the water control starts from the corn tasseling period to the end of the growth period (T1 treatment) and the natural drought at the whole growth period (T2 treatment) in arid and semi-arid regions, the similarities and differences of the formation of drought disasters to the same crop were revealed in arid and semi-arid regions, in order to provide a theoretical basis for grasping the crop drought inducing-disaster process in different climatic regions. The results showed that different drought stresses affected significantly the plant height, leaf area and chlorophyll content of maize in arid and semi-arid regions. During the whole growth period of drought treatment, the response of maize in arid area to drought stress was more sensitive than that in semi-arid area, while T1 treatment had more significant effects on the growth of maize plant height and leaf area per plant in semi-arid rain-fed area. The leaf area per plant of maize under different drought treatments in semi-arid area showed an increasing trend from the horse chestnut stage to grain filling stage as a whole. Although drought stress reduces the leaf area per plant of maize, in order to ensure the later growth and development of plants, the increase of leaf area make up for the lack of photosynthetic yield due to drought stress. Therefore, in order to ensure the yield of maize in arid and semi-arid regions, semi-arid areas are suitable for planting varieties with strong photosynthetic capacity, arid areas are suitable for planting varieties with suitable plant height and leaf area, and the tasseling period is a sensitive period for maize growth and development to drought in semi-arid regions.

A torrential rain struck Qingyang on July 15, 2022, which is located in semi-arid region of eastern Northwest China, causing the daily rainfall and hourly rainfall at several stations to exceed the historical extreme values. The formation mechanism of the torrential rain in semi-arid region of Northwest China is analyzed based on multi-source observation data and ERA5 reanalysis data, so as to provide some useful reference for rainstorm forecast in arid and semi-arid areas. The results show that the torrential rain process occurred under the background of weak synoptic scale baroclinic forcing, weak unstable energy and deep wet layer in the complex terrain of the Loess Plateau, with characteristics of strong locality and long duration of heavy precipitation, which is a warm-sector torrential rain. The special circulation configuration of South Asian high, western Pacific subtropical high and pressure system at the lower level is conducive to the occurrence and development of mesoscale convective system. Convective initiation and development were triggered by surface wind convergence line and low-level southerly jet. Development and long-time maintenance of the low-level jet intensified surface convergence line continuously. The left side of low-level jet (rainstorm area) formed two stable secondary circulations with the right side of the exit and entrance of it, respectively, which is the key factor for the maintenance of the convective system. The release of condensation latent heat caused local frontogenesis and low-level positive vorticity development, which is another important factor for development and maintenance of convective systems, and it is also an important reason for maintenance of atmospheric instability. The mesoscale convective system exhibited deep, low center of mass and quasi-stationary characteristics under the combined effects of the above mentioned factors, the radar echoes were characterized by backward propagation and train effect.