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Objective The increase in atmospheric CO2 and the associated global warming is expected to affect plant growth and development. This paper investigates the spatiotemporal variation in vegetation phenological traits and peak NDVI of plants in Hetao Irrigation District in Inner Mongolia. [Method] The analysis was based on MOD13Q1 data from 2001 to 2021. The impact of climatic factors on spatiotemporal variation in the start of season SOS, the end of season (EOS), the length of season (LOS), the peak of season (POS), and the normalized difference vegetation index (NDVI) of the vegetations in the region was analyzed using the two-logistic and four-parameter model. [Result] The SOS started from the end of May to the middle of June, and ended from the middle of September to the beginning of October. The annual peak LOS and POS ranged from 95 to 116 days, and from 200 to 220 days, respectively. The annual peak NDVI ranged from 0.5-0.7. Climate change delayed the onset of SOS, reduced LOS, and elevated peak NDVI. Additionally, the delayed SOS contributed to the decrease in LOS. The changes in EOS and POS with climate were consistent. SOS, EOS and POS were negatively correlated to temperature and positively correlated to precipitation. The peak NDVI was positively correlated to temperature and precipitation. [Conclusion] The vegetation phenology and peak NDVI in the Hetao Irrigation District were spatially heterogeneous, and the impact of climatic factors on them also varied. [ABSTRACT FROM AUTHOR]

[Objective] A pre-planting border irrigation in spring coupled with a drip irrigation in summer during crops growth season is an irrigation technique to reduce soil salinity and safeguard crops growth in the salt-affected soils in the Hetao Irrigation District in Inner Mongolia. This paper investigates the impact of different combinations of irrigation amounts in the dual irrigations on changes in soil water and salt, as well as the growth of sunflower. [Method] The field experiment compared two spring (S) irrigation amounts: 95 mm and 135 mm, and three summer (W) irrigation amounts: 68, 100 mm and 135 mm. In each treatment, we measured the spatiotemporal changes in soil water and salt, as well as crop growth characteristics. [Result] ① The soil water content in the S135W135 treatment was the highest among all treatments during the experimental period, with the average soil water content and saturation being 17.10% and 75.53%, respectively. The coefficient of variation of soil water content in the S95W135 treatment was 22.40%, the lowest among all treatments. ② Depending on the summer irrigation amount, the desalination rate of the 0-80 cm soil layer under S135 and S95 varied from 32.64% to 50.50% and 21.8% to 38.87%, respectively. Although the spring irrigation amounts did not significantly affect immediate post-irrigation salt content, the S135W100 and S95W135 combinations showed deeper leaching depths and higher desalination rates (40.77% and 33.37%, respectively) than other treatments. ③ Aboveground dry matter production was significantly higher in the S95W135 and S135W100 combinations than in other combinations, surpassing the S135W135 combination by 10.55% and 9.94%, respectively. The S135W100 combination achieved the highest water use efficiency at 21.59%, an increase of 13.03% compared to S135W135. [Conclusion] Reducing spring irrigation by 30% to 95 mm combined with a summer drip irrigation of 135 mm is the most efficient irrigation scheme for sunflower cultivation in the salt-affected soils in the Hetao Irrigation District. [ABSTRACT FROM AUTHOR]

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[Objective] Water flow and solute transport in soil is important not only for plant acquisition of resources from soil but also for soil and water environment. In terrestrial ecosystems, they are impacted by numerous factors. The objective of this paper is to investigate the effects of drip irrigation amount on spatiotemporal change in water and nitrogen in Hetao Irrigation District, Inner Mongolia. [Method] A field experiment was conducted to measure the movement of water, nitrate and ammonium in soils, with the irrigation amount controlled at 6 mm (D1) or 60 mm (D2). The measured data was used to calibrate the HYDRUS-2D model, and the calibrated model was then used to elucidate how increasing the irrigation amount to 120 mm would affect water and nitrogen movement. [Result] Irrigation increased soil water content in all growth stages. Following irrigation and fertilization, ammonium and nitrate contents both increased rapidly and then decreased. On average, ammonium and nitrate in the 0~10 cm soil layer decreased by 60.0%~62.0% and 40.0%~46.7%, respectively, after the D1 and D2 irrigations, with the decreasing rate varying with growing stage. Compared to D2, D1 increased soil water content at jointing, heading and filling stage by 5.9%, 8.0% and 6.7%, respectively. Soil ammonium and nitrate both decreased along the soil depth. Nitrate accumulation decreased gradually when the crop grew from jointing stage to filling stage. The simulated soil water content and nitrogen agreed well with the measured data. [Conclusion] Experimental data and simulated results showed that irrigating the maize by 120 mm of water can effectively reduce accumulation of nitrate in the 0~60 cm soil layer, and that increasing irrigation frequencies can further curtail nitration accumulation in the 60~100 cm soil layer. These results provide guidance for improving irrigation and fertigation for maize production in Hetao Irrigation District. [ABSTRACT FROM AUTHOR]

[Objective] Alfalfa is sensitive to water stress at branching stage, but how a simultaneous salinity stress affects this sensitivity is not well understood. The objective of this paper is to address this issue. [Method] Pot experiments were conducted in 2018-2019 at the Shengmu High-tech Economic Park, in Dengkou County, Inner Mongolia. It consisted of three water treatments with the soil water content kept at 55%~70% (W1), 75%~85% (W2), and 85%~100% (W3) of the field capacity, respectively. Each water treatment had four salinity stresses with the soil salt content set at 1.0 (S0), 1.5 (S1), 3.0 (S2) and 4.5(S3) g/kg, respectively. In each treatment, we measured osmotic substances, antioxidant enzymatic activities, above- and below-ground biomass at early flowering stage. [Result] Water and salinity stresses reduced water consumption and aboveground biomass more considerably when they worked collectively than working separately. When the water stress was minor, however, imposing a slight salinity stress with soil salt content ≤3 g/kg can increase the contents of proline and Na+, boosted peroxidase (POD) activity, and reduced superoxide dismutase (SOD). This alleviated oxidative damage of the water stress, thereby promoting crop growth. Compared with S0+W1, S2+W1 increased the contents of proline and Na+, and boosted POD activity, by 74.28%, 17.28% and 34.60%, respectively, while reducing SOD activity by 9.87%. These led to an increase in water consumption and aboveground biomass by 6.48% and 2.17%, respectively. [Conclusion] When water stress is not severe, imposing a slight salinity stress can improve the tolerance of alfalfa to water and salinity stress at branching stage. For all treatments we studied, keeping soil salt content in the range of 2~3 g/kg and soil water content in the range of 70%~85% of the field water capacity was optimal to improve resistance of the crop to both salinity and water stresses. [ABSTRACT FROM AUTHOR]

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Objective Global warming has resulted in change in precipitation across many regions around the world. In this paper, we analyze the stable isotopes in precipitation in Ordos of Inner Mongolia, and then used them to track the origin of the water vapor in the irrigation areas proximal to the Yellow River in the region. Method Rainfalls were sampled from June to September in 2020, and stable hydrogen and oxygen isotopes in them were measured. Their correlation with factors including air temperature and daily precipitation was analyzed, from which we established the downline equations. The origin of the water vapor was tracked based on the variation of deuterium surplus value; reliability of the results was determined by the HYSPLIT air mass trajectory model Result The isotopes in the sampled precipitation during the experimental period was significantly lower than that in other months, showing their significant correlation with rainfall with p=0.01. The downline equation was D=7.1318O-1.67, affected by evaporation greatly. Water vapor in June was affected by both the westerly belt and the polar air mass, accompanied by water vapor coming from the southeast coastal region. The water vapor in July and August was similar, coming from northwestern China. Water vapor in September was affected by the water vapor in the westerly belt, the polar air mass and local evapotranspiration.Conclusion Precipitation is the main factor determining its isotope content and origin. The HYSPLIT simulation and dynamic-change analysis of the deuterium surplus value showed that the water vapor in the westerly zone is the origin of the water vapor seen in the studied area. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Irrigation & Drainage is the property of Journal of Irrigation & Drainage Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)