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[Objective] Scutellaria baicalensis Georgi (SBG) is a Chinese medicine. This paper studies the combined effect of initial soil water content and progressive drought on physiological traits and quality of SBG. [Method] The pot experiment was conducted in a mobile water shelter. The initial soil water content in the pots were controlled at 40%, 60% and 80% of the field capacity (FC) to represent severe, moderate, and mild drought, respectively. In each treatment, we measured the biomass, photosynthetic characteristics, osmotic substances, activities of antioxidant enzymes and active ingredients of the plants. [Result] ① No significant difference in biomass accumulation was found between the treatments. ② During the stress period, baicalin content was significantly higher in the 80%FC treatment, baicalein content was significantly higher in the 40%FC treatment and the baicalin content decreased with initial soil water treatment in the order of 40%FC>60%FC>80%FC. When the soil water content was 40%FC and 60%FC, the baicalin content was 17.3% and 11.3% higher than that when soil water content was 80%FC. Change in soil water contents did not have a significant impact on baicalein content. ③ Net photosynthetic rate, transpiration rate, stomatal conductance and intercellular carbon dioxide concentration all decreased as the plants grew, regardless of the soil water treatments. 8-10 d after the onset of water stress, the net photosynthetic rate did not show significant differences between the 60%FC and 80%FC treatments. ④ Under water stress, the content of malondialdehyde and proline in all treatments increased as the plants grew. The proline content was the highest in the 80%FC treatment, reaching 121.66 µg/g. ⑤ The activities of POD and CAT responded to water stress similarly, both increasing gradually as water stress persisted. The impact of soil water on activity of SOD was ranked in the order of 40%FC>60%FC>80%FC. ⑥ The active ingredients were higher in the 40%FC and 60%FC treatments. [Conclusion] Severe progressive drought with the soil water content kept at 40%FC reduced photosynthesis and increased baicalein content, osmolytes and activity of antioxidant enzymes. Mild and severe droughts by keeping the soil water content at 40%FC and 60%FC can improve accumulation of active ingredients in SBG. [ABSTRACT FROM AUTHOR]

Droughts are increasing in frequency and intensity as the global climate changes. Risk assessment for agricultural drought disasters is an important approach for disaster prevention and mitigation. Based on the formation mechanism of natural disaster risk, the index system model of agricultural drought risk assessment in North China was constructed, and the robustness of the established risk assessment model was tested by using the internal test method. Then based on the characteristics of agricultural drought risk formation in North China, the paper proposes corresponding risk prevention recommendations. The conclusions were as follows: when adjusting the indices and methods in the risk assessment model, the range of changes in the agricultural drought risk ranking for each city was mostly 1-2.5 places, and the model was relatively robust. With the exception of Beijing and Tianjin, which had the highest disaster prevention and mitigation capacity, central and northern China had the highest agricultural drought risk, which was previously linked to the high risk and vulnerability of these regions. The agricultural drought risk in northern Henan and southern Shandong is low, mainly due to the low risk. The 34 cities in North China can be divided into 6 agricultural drought risk clusters, which are not dispersed in space and cross-city distribution, and have good aggregation. Cluster 4, located in the northernmost mountainous areas, has the highest risk of drought, which is associated with high environmental vulnerability and low capacity for disaster prevention and mitigation, so agricultural areas should be reduced and agricultural input should be increased. Clusters 2, 5 and 6, located in the central and southern regions, have higher grain acreage and yields due to drought, so agricultural drought risk can be further reduced by increasing agricultural input and improving irrigation guarantee rate. [ABSTRACT FROM AUTHOR]

In order to deeply analyze the drought and flood disaster response patterns of Tuojiang River Basin under the background of climate anomalies, this paper reconstructs the time series of drought and flood disaster of Tuojiang River Basin in the Qing Dynasty, and analyzed its related data with mathematical statistics, mutation test, power spectrum cycle analysis, ADF and Granger causality test, etc., to explore the occurrence patterns of drought and flood disasters in the Tuojiang River Basin in the Qing Dynasty and its climate driving force factors. The results show that, during the Qing Dynasty, 208 drought and flood disaster occurred in the Tuojiang River Basin, with an average of one drought and flood disasters occurring every 1.29 years. There were more flood disasters than drought disasters, with a total of 21 persistent flood and drought disasters and an overall high level of severity of disasters. Drought and flood disasters were interspersed frequently, and there were also drought and flood disasters coexisting during the same year. Drought and flood disasters were concentrated in a chain-like distribution from 1800 to 1910.The number of disasters peaked in the middle of the Qing Dynasty, and mega-disasters were concentrated in the middle and late Qing Dynasty. The year 1863 was an important mutation point for drought and flood disasters, after which the number of disasters increased significantly. Drought and flood disasters in the Qing Dynasty were significantly correlated with the average annual sunspot number, and continuous disaster events were more frequent around sunspot extreme years.The change cycle of drought and flood disasters is about 2.5 a, which is strongly consistent with the ENSO cycle. The number of drought and flood disasters in the Tuo River Basin was significantly higher during ENSO event years. With a lag period of 1a, sunspot activity and ENSO events are the main climatic triggers of drought and flood disasters changes. The research results not only fill the research gap of drought and flood disasters mechanism in the Tuojiang River Basin under climate change, but also enrich the knowledge of spatial and temporal distribution pattern and regularity of drought and flood disasters in the Yangtze River Basin. It provides a useful reference for strengthening the scientific use of water resources and disaster prevention and mitigation, and also provides an important reference for the flood and drought prevention and ecological civilization construction in the Tuojiang River Basin. [ABSTRACT FROM AUTHOR]

Copyright of Ecological Science is the property of Ecological Science 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 Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research 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 Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research 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 Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research 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.)

Agriculture is an important part of the global ecosystem carbon cycle, which is greatly affected by drought. Therefore, understanding the impact of drought on the carbon sink intensity of agro-ecosystems helps to figure out the change regular of agro-ecosystem carbon cycle and provide a theoretical basis for realizing the control of carbon emissions. In this paper, the net ecosystem exchange (NEE) of winter wheat-summer maize rotation system in North China Plains is simulated by vegetation photosynthesis and respiration model (VPRM), and Drought Severity Index (DSI) is calculated based on evapotranspiration and normalized vegetation index to evaluate the agricultural drought intensity. The spatiotemporal response of NEE to agricultural drought is also assessed by using geographic detectors and de-trended analysis. The results show that the agricultural drought intensity in the northern part of North China Plains is more than that in the southern part of North China Plains during the growth period of winter wheat, and the agricultural drought intensity gradually decreases with the development of winter wheat. During the growth period of summer maize, North China Plains enters the rainy season and is generally wet. The carbon sequestration capacity of cropland ecosystem decreases with the increase in agricultural drought intensity, and the sensitivity of NEE of cropland ecosystem to agricultural drought is greater in the middle growth stage of winter wheat/summer maize than in the early and late growth stages. The spatial variability of agricultural drought has the largest explanatory power for NEE of winter wheat in March (q=0.68l). The explanatory power for NEE of summer maize is the highest in August (q=0.792). With the increase in agricultural drought intensity, wheat and maize fields change from strong carbon sink to weak carbon sink if grain carbon content is not considered, and finally change to carbon source if grain carbon content is considered. [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 China Rural Water & Hydropower is the property of China Rural Water & Hydropower 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 Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology 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.)

[Objective] Drought is the most important abiotic stress facing agricultural management and economic development in many regions and countries. The aim of this paper is to identify the spatiotemporal variation of drought in Yunnan Province, using the standardized precipitation index (SPI). [Method] Meteorological data measured over the past 31 years from 36 meteorological stations across the province were used in the analysis. Multi-scale variations of the droughts in both time and space were calculated using SPI, GIS, nonparametric Mann-Kendall trend test and other methods. [Result] ①Both annual and seasonal SPI fluctuated temporally, but we identified a small annual increase in spring SPI, small annual decreases in summer, autumn and winter SPI. The autumn SPI varied mostly, and the winter SPI least. The annual SPI varied from -1.95 to 1.44. ②The annual drought frequency varied from 32.26% to 50.00%, with the severity of most droughts varying from mild to extreme range. Spatially, drought occurred more frequently in Wenshan, Honghe, Kunming, Chuxiong and Dehong than in other regions in the province. ③Seasonally, drought frequency in spring, summer, autumn and winter was 39.86%, 39.83%, 38.43%, and 41.33%, respectively. Although drought frequency in different seasons was close, their severity differed considerably. ④Annually, except for five meteorological stations which found increased drought frequency, drought frequency in other stations remained statistically the same. Seasonally, most stations showed decreased drought frequency in spring, eleven stations showed increased drought frequency in summer, and six and two stations showed increased autumn droughts and winter droughts, respectively. [Conclusion] Annual and seasonal drought frequency is spatially heterogeneous across the province. Droughts in the province are seasonal, with droughts occurring in spring and winter more frequently and severely. [ABSTRACT FROM AUTHOR]

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Copyright of Chinese Journal of Agrometeorology is the property of Editorial Board of Chinese Journal of Agrometeorology 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 China Rural Water & Hydropower is the property of China Rural Water & Hydropower 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.)

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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 Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research 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 Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research 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 Natural Resources / Ziran Ziyuan Xuebao is the property of Journal of Natural Resources 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 Chinese Journal of Oil Crop Sciences is the property of Oil Crops Research Institute of Chinese Academy of Agricultural Sciences 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 Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research 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 Chinese Journal of Agrometeorology is the property of Editorial Board of Chinese Journal of Agrometeorology 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.)

:Drought has been a major natural disaster for mankind since ancient times. Even today, with the development of science and technology, the disastrous consequences caused by droughts are still everywhere. In this paper, the evolution characteristics of the drought and its correlation with circulation in Henan Province from 1970 to 2019 are analyzed by using the methods of standardized precipitation evapotrans- piration index (SPEI), Mann Kendall test and cross wavelet analysis. The results show that based on SPEI value, the climate in Henan Province has gradually become arid in recent 50 years. In terms of spatial variation, the drought in spring, summer and winter is significant in the northwest and relatively humid in the southeast. From the circulation correlation, the North Atlantic Oscillation (NAO), Arctic Oscillation (AO) and Southern Oscillation (SOI) have a strong correlation with droughts in spring, summer and autumn in Henan Province, and the Pacific Decadal Oscillation (PDO) and SOI have a strong inter-annual correlation with droughts in Henan Province. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences 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.)

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Copyright of Journal of Northwest A & F University - Natural Science Edition is the property of Editorial Department of Journal of Northwest A&F University (Natural Science Edition) 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.)

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【Objective】The present paper aimed to explain the changes of hydrothermal resources in the growth period of foxtail millet and maize in Heilongjiang region, and to provide theoretical basis for crop safety production.【Method】Based on the daily weather data from 1957 to 2013 in Raoyang County and Penman-Monteith formula, precipitation anomaly percentage and growth length day（GDD）, this paper analyzed the changes of hydrothermal resources in Raoyang County from June to September.【Result】（i） The size of ET0 was June > July > August > September, and the climatic tendency rates were-5.85,-1.96,-2.59 and-1.46 mm 10 a-1, respectively. The decrease of ET0 in different months was affected by different ten days, June was mainly affected by mid-late days, July was affected by mid-late days, August and September were affected by early and mid-late days, respectively.（ii） The frequency of drought from June to September was 33.33 %, 19.30 %, 31.58 % and 38.6 % respectively. Light drought was dominant in June and July, light drought was dominant in August and moderate drought was dominant in September.（iii）From June to September, the growth degree days were 459.58, 516.49, 470.40 and 301.64 ℃·d, respectively. The climatic tendency rates were 1.19, 3.28, 0.46 and 3.10 ℃·10 a-1, respectively. The increase of growth duration in June and August was affected by the first and middle ten days, July by the first and second ten days, and September by all stages, with the greatest increase in the latter ten days. 【Conclusion】In the future interannual changes, for crops such as millet and maize growing in Heilonggang from June to September, the heat resources were abundant and increasing, but the drought risk will increase in July and August. Therefore, in agricultural production, we should improve the irrigation system in July and August, and strengthen the measures of water conservation and drought resistance in this stage. [ABSTRACT FROM AUTHOR]

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Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research 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.)

【Objective】The present paper aimed to understand the difference of drought resistance among hybrid soybean varieties, thus to select drought tolerant hybrid soybean varieties.【Method】3 hybrid soybean varieties were used as experimental materials and different concentrations of PEG-6000 solution (5%,10% and 20%) hydroponic model were used to simulate drought stress in soybean seedling stage. To identify the physiological response and drought resistance of 3 hybrid soybeans, chlorophyll content, photosynthetic physiological index, osmotic regulator content and antioxidant enzyme activity of leaves in seedling stage were measured after drought stress. 【Result】With the increasing concentration of PEG-6000 solution, there were significant differences in the related drought resistance indicators of the three hybrid soybeans and the growth of soybean seedlings was gradually significantly inhibited. The chlorophyll content of soybean seedlings was detected, and it was found that with the increase of PEG-6000 solution concentration, its content showed an upward trend, the most significant being dominant Hybrid soybean-A-5. In terms of photosynthetic physiological indexes of soybean seedlings, the variation trends of net photosynthetic rate (Pn), transpiration rate (Tr), intercellular carbon dioxide concentration (Ci) and stomatal conductance (Gs) of leaves of three hybrid soybean seedlings showed significant differences. The response of different soybean varieties to drought stress under different treatment conditions was analyzed. The results showed that soybean seedlings could respond to drought stress through osmoregulation and activating antioxidant defense system was analyzed.The content of each substance changed significantly with the increase of stress degree. There were also significant differences among different varieties. The order of drought resistance of 3 hybrid soybeans was obtained by comprehensive analysis of membership function value method, Hybrid soybean-A-5> Hybrid soybean No.6>Jindou 48.【Conclusion】 The photosynthesis inhibition, osmotic adjustment and antioxidant enzyme activities could respond to drought stress of 3 hybrid soybeans. The Hybrid soybean-A-5 can be used as a demonstration of drought resistant hybrid soybean to promotion and demonstration in Huanghuaihai Area. It also provides an important reference for drought resistant breeding of hybrid soybean in later stage. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Agricultural Science & Technology (1008-0864) is the property of Journal of Agricultural Science & Technology 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.)

Quantitatively evaluation of satellite precipitation and potential evapotranspiration products with the high resolution, wide coverage and dynamic continuity is an important foundation for drought monitoring over mainland China. This paper examined the accuracy of products and the utility of drought monitoring using the newly released long-term (more than 30 years) satellite precipitation products (climate hazards group infrared precipitation with station, CHIRPS) data version 2.0 and potential evapotranspiration products (global land-surface evaporation: the Amsterdam methodology, GLEAM) dataset. We selected standardized precipitation evapotranspiration index (SPEI) and six statistical and classification measures indexes to evaluate accuracy and the utility of CHIRPS and GLEAM-Ep (potential evapotranspiration derived from GLEAM), with China Gauge-based Precipitation Daily Analysis dataset (CGDPA) and potential evapotranspiration calculated by Penman-Monteith (PM-Ep) as evaluation reference data sets. The results showed that CHIRPS and GLEAM-Ep performed well in eastern and southwest of China. However, their performance in western China was uncertain due to the sparsity of meteorological stations. SPEIs (SPEI value calculated by the CHIRPS and GLEAM-Ep) had a good performance on drought monitoring in eastern and southwestern China. Values of correlation coefficient (CC) between SPEIs and SPEIm (SPEI value calculated by the CGDPA and PM-Ep) were more than 0.6 in southeastern China, southwestern China, the middle and lower reaches of the Yangtze River region and northern China, especially in relatively humid areas, which the correlation coefficient values were more than 0.7 and the root mean-squared error (RMSE) values were less than 0.8. In order to further evaluate the performance of SPEIs in drought monitoring at spatial and temporal scales, the SPEIs3 (SPEIs at three-month scale) and SPEIm3 (SPEIm at three-month scale) in southeastern China, southwestern China, the middle and lower reaches of the Yangtze River region and northern China were compared. SPEIs3 had a better simulation effect on the evolution process of the ratio of drought area in those regions during1981-2016. And the success ratio of simulating drought duration was about 0.93, 0.57, 0.71 and 0.81, respectively. Moreover, SPEIs3 displayed a high accuracy over the four regions in capturing drought, which was the spatial distribution of typical drought events on specific month. In conclusion, SPEI based on long-term CHIRPS and GLEAM-Ep could be applied to monitor and evaluate drought in eastern and southwestern China. This paper can provide reliable reference for monitoring and warning of drought events and water resources management in those regions. [ABSTRACT FROM AUTHOR]

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Soil moisture and nitrogen (N) nutrient are the principal factors affecting rice production. Elucidation of their influences and coupling effects on grain yield of rice (Oryza sativa L.) would have great significance for high yielding and high efficiency of rice. As early as in 1911, Montgomery had began to study the effects of soil fertility on water consumption of maize in Mabraka, and Painten and Leamer noted that higher yield was obtained by applying more fertilizer under the condition of higher soil water potential in 1953. Domestic and foreign scholars have conducted extensive researches on the interaction of water and fertilizer. The existed researches focused on crop growth development, photosynthetic characteristics, yield and quality formation, nutrient and water use efficiency and other aspects of the studies, but most researches focused on the ground, few papers for the root characteristics, and the conclusions were not consistent. The purposes of this study were to investigate the effects of water and N coupling on root morphology and physiology, grain yield and N fertilizer use efficiency. A mid-season japonica rice cultivar of Xudao 3 was planted. Three treatments of different N levels, i.e. no N fertilizer application, normal N (MN, 240 kg/km²) and high N (HN, 360 kg/hm²) and 3 irrigation regimes, i.e. submerged irrigation (0 kPa), alternate wetting and moderate drying (-20 kPa) and alternate wetting and severe drying (-40 kPa) were conducted. The results showed that there was a significant interaction between irrigation regimes and N applications, while not significant between the years for the main indices. In the same N condition, grain yield increased under the mild water stress, yet decreased significantly under the condition of alternate wetting and severe drying, an average reduction of 29.8%. When compared with no N fertilizer, rice yield of MN and HN treatment improved by from 54.0% to 60.6% (submerged irrigation), from 57.0% to 66.4% (-20 kPa) and from 33.0% to 61.0% (-40 kPa), and the result indicated that the application of N fertilizer could enhance rice yield significantly. Compared with the MN, grain yield under the condition of HN treatment was reduced, but the difference was not significant, except while water stress was severe, the yield of HN decreased significantly (P<0.05). High N fertilizer application had aggravated the soil drought, and reduced the effect of fertilizer regulation. The grain yield was the highest under the interaction of MN and mild water stress through the analysis of coupling effect of water and N, and the reason was it improved the filled grain rate and the 1000-grain weight when compared with other treatments. Under mild drying condition, root length, root dry weight, root activity, total root absorbing area, activity absorbing area and N metabolism enzyme activity at main growth stages were increased, but root-shoot ratio was decreased after panicle initiation stage. Mild water stress and MN enhanced rice yield and N use efficiency, being the best mode in this paper referred as the water-nitrogen coupling management mode. The opposite result was observed under the condition of alternate wetting and severe drying. Correlation analysis showed that grain yield was positively correlated to all the above morphological and physiological indices at main growth stages with the exception of negative correlation of the root-shoot ratio at the stage of heading. A negative correlation was observed between the N agronomy efficiency and the root dry weight, dry weight density, root-shoot ratio, while there was significant or extremely significant positive correlation between root active absorbing area, root activity at heading stage and N agronomy efficiency. These results suggest a good root morphology can increase root activity and N metabolism enzyme activity through the regulation of water and N, and will be much more beneficial to increasing grain yield and N use efficiency in rice production. [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 China Rural Water & Hydropower is the property of China Rural Water & Hydropower 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 China Rural Water & Hydropower is the property of China Rural Water & Hydropower 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 Central China Normal University is the property of Huazhong Normal University 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.)

[Objective] The present paper aimed to provide a scientific reference for drought prevention and disaster avoidance of sugarcane production, the temporal and spatial characteristics of sugarcane drought in different growth period in Guangxi were analyzed in recent 60 years. [Method] Firstly the development period of sugarcane, soil data and meteorological data from 1961 to 2020 in Guangxi were collected for the study. Under major concentration for effectiveness of precipitation and dynamic change characteristics of crop coeffi cient, the temporal and spatial variation characteristics of sugarcane drought in growth period were analyzed by linear and periodic analysis method and spatial station technology basing on crop water deficit index. [Result] The interannual drought incidence was the highest in maturity stage, followed by stem elongation stage, and the least in seedling stage and in tillering stage. Light and medium drought are mainly in seedling stage, tillering stage and stem elongation stage. Heavy and extreme drought are mainly in maturity stage. During the study period, there was no obvious linear change trend in the interannual drought incidence at all levels and with a periodic change on the scale of 2 - 5 years. The years of occurrence were mainly in 1970s and 1980s. In terms of spatial distribution, in the seedling stage light drought and medium drought were mainly distributed in the west and south of Guangxi. The occurrence frequency of light drought was less than 40%. The occurrence frequency of medium drought was less than 30 % . The occurrence frequency of heavy drought was less than 10 % and its distribution range was small. In the tillering stage, light drought occurred in all over the region. The occurrence frequency in the southwest of Guangxi was the highest, generally between 21 % and 40%. Medium drought was mainly distributed in the southwest of Guangxi and the occurrence frequency was less than 10% . The occurrence frequency of severe drought was less than 10 % and its distribution range was small. In the stem elongation stage, mild drought was distributed in the whole region with the occurrence frequency between 11 % and 70%. Medium drought was mainly distributed in the northeast of Guangxi with the occurrence frequency between 21 % and 60%. Heavy drought was mainly distributed in the northeast of Guangxi with the occurrence frequency less than 20%. There was no extreme drought in the seedling stage, tillering stage and stem elongation stage during the study period. In the maturity stage, light drought, medium drought, heavy drought and extreme drought were distributed in whole study region. The occurrence frequency of light drought was less than 30%. The occurrence frequency of medium drought and severe drought were less than 40%. The occurrence frequency of extreme drought was the most and its distribution was wide. The regions with high extreme drought occurrence frequency were mainly distributed in the center, south and east of Guangxi with the occurrence frequency between 31 % and 50%. [Conclusion] The light and medium drought are the main drought in the seedling stage, tillering stage and stem elongation stage of sugarcane in Guangxi during the sugarcane development. The heavy and extreme drought is the main drought in the maturity stage. In the maturity stage of sugarcane, the heavy and extreme drought occur once every 2 - 3 years in the center, south and east of Guangxi. The regions above should be get more attention for drought prevention and disaster avoidance. [ABSTRACT FROM AUTHOR]

As one of the three alpine flowers in the world and one of the ten traditional famous flowers in China, Rhododendron has high ornamental value and broad landscape applications. However, most of them are naturally distributed in high-altitude mountains, and they prefer cool and humid climate for the restriction of genetic mechanism. Drought is the key factor to restrict their ex-situ conservation and landscape application. As Rhododendron have many different species, cultivars and ecological types, distributed in a wide area, the mechanisms of different species or cultivars responses to drought stress are different. In this paper, how Rhododendron responses to drought stress and the effects of exogenous substances on improving the drought resistance of Rhododendron in China and abroad were reviewed from the aspects of seed germination, morphological and anatomical characteristics, physiological and biochemical parameters, gene expression, etc. In addition, the deficiency of current research and the future research directions were also discussed. It is proposed that the water use strategy and drought resistance mechanism of different ecological types and different drought resistances of Rhododendron should be future studied, as well as the gene regulation mechanism of mycorrhizal fungi for improving the drought resistance and the screening of excellent strains. This study provides the basis for the diversity conservation, the exploitation of drought resistance resources and the landscape applications of Rhododendron in China. [ABSTRACT FROM AUTHOR]