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Drought and waterlogging have been two of the most important abiotic stresses on plant growth and development. Furthermore, plants can suffer from the dual stresses of drought and waterlogging in some cases, including drought-flood abrupt alternation (DFAA) stress. The occurrence of DFAA is ever increasing in the middle and lower reaches of the Yangtze River, China, in recent years, due mainly to the global climate. There is a severe threat to the sustainable crop production. However, it remains unknown about the DFAA impact on the leaf senescence and grain yield of maize, together with the underlying mechanisms. The purpose of this study was to investigate the effects of different water stress treatments at the jointing stage on the net photosynthetic rate (Pn), leaf SPAD values, activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), soluble protein and malondialdehyde (MDA) contents at the key growth stages, ear number per plant, kernels number per ear, and one-thousand weight of maize. Taking the spring maize "Yidan 629" as the research object, a leaching-pond experiment was carried out in Jingzhou City, Hubei Province, China in 2021. The treatments included the moderate drought (with 55%-60% field capacity as irrigation low limit for 18 d, D), waterlogging for 6 d (W), moderate drought immediately followed by waterlogging for 3 d (D-LW), moderate drought immediately followed by waterlogging for 6 d (D-MW), moderate drought immediately followed by waterlogging for 9 d (D-HW) at the jointing stage, and well-water during the whole grown season (CK) of maize. Leaf senescence traits were characterized to determine the grain yield and its components at the bell, tasselling and filling stages. The results showed that there were comparable SPAD values, SOD, CAT, and POD activities, soluble protein content, Pn at the tasselling and filling stages, and ear number per plant, kernels number per ear, and one-thousand weight in the D-LW treatment, compared with the CK. Thus, a relatively high grain yield was obtained in the D-LW treatment. This indicated that the moderate drought immediately followed by waterlogging for 3 d at the jointing stage reduced the leaf senescence, thus stabilizing the grain yield of maize. Compared with the CK, the treatments D, W, D-MW, and D-HW significantly reduced Pn, SPAD values, activities of SOD, CAT, and POD, and soluble protein content, whereas, there was a significant increase in the MDA content of maize leaves at the bell, tasselling, and filling stages, resulting in the low ear number per plant, kernels number per ear, and one-thousand weight, and correspondingly smaller grain yield of maize. Consequently, the treatments D, W, D-MW, and D-HW significantly reduced the grain yield of maize by 13.3%-72.7%. Overall, the adverse effects of water stress treatments on the leaf senescence and grain yield were ranked in the descending order of D-HW, D-MW, W, D, D-LW treatment. Therefore, the moderate drought immediately followed by waterlogging for 3 d at the jointing stage shared the compensatory on the SPAD value, antioxidant enzyme activities, soluble protein content and Pn of maize leaves, leading to a relatively high grain yield of maize. The finding can also provide a theoretical reference to cope with the drought-flood abrupt alternation disaster, and then manage the irrigation and drainage for maize. [ABSTRACT FROM AUTHOR]

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.)

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board 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.)

To explore the effects of different types of nitrogen fertilizers and different tillering ratios on runoff nitrogen loss, ammonia volatilization, and nitrogen fertilizer use efficiency in direct-seeded rice fields, seven nitrogen application treatments were arranged in field plot experiments with three replicates, including the blank control (CK) without nitrogen fertilizer, common compound fertilizer (base fertilizer), and urea (tiller fertilizer) at ratios of 4∶6 (U40) and 6∶4 (U60), controlled-release blended fertilizer (base fertilizer) and urea (tiller fertilizer) at ratios of 7∶3 (C70) and 10∶0 (C100), and seaweed polysaccharide urea at ratios of 4∶6 (H40) and 6∶4 (H60) . The results showed that runoff N loss mainly occurred after basal fertilizer application and was dominated by ammonium nitrogen (NH+ 4-N) . Compared with the U60 treatment, Total N loss in the C100, H60, U40, C70, and H40 treatments decreased by 7.20%, 13.36%, 24.30%, 26.41%, and 35.92%, respectively. The order of the amount and rate of ammonia volatilization loss between different N fertilizers was as follows： treatment of common compound fertilizer with urea > treatment of seaweed polysaccharide urea > treatment of controlled-release blended fertilizer with urea. Compared with the U60 treatment, the total ammonia volatilization loss in the U40, H60, H40, C70, and C100 treatments decreased by 7.89%, 20.81%, 27.84%, 42.08%, and 47.00%, respectively, with significant differences between the C70 and C100 treatments (P<0.05) . The total N losses from runoff were reduced by 24.30%, 20.70%, and 26.04% for U40, C70, and H40 treatments compared with U60, C100, and H60 treatments, respectively. N fertilizer setback reduced runoff N loss and ammonia volatilization loss in the U40, C70, and H40 treatments, with no yield loss. The maximum yield of 9 116.67 kg·hm-2 and the highest N fertilizer agronomic utilization of 29.64 kg·kg-1 occurred in the C70 treatment, and the apparent N fertilizer utilization was 41.99%. The study suggested that the C70 and C100 treatments both significantly reduced runoff N loss and ammonia volatilization loss in direct-seeded rice fields, while improving N fertilizer utilization efficiency and yield. The ratio of 7∶3 between controlled-release blended fertilizer (base fertilizer) and urea (tiller fertilizer) at the base tiller fertilizer ratio is worth pursuing for productivity and environmental protection. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Hydrobiology is the property of Editorial Department of Journal of Hydrobiology 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 Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board 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 Acta Agriculturae Zhejiangensis is the property of Acta Agriculturae Zhejiangensis 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 Hydrobiology is the property of Editorial Department of Journal of Hydrobiology 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 Southwest China Journal of Agricultural Sciences is the property of Editorial Department of Southwest China Journal 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 Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering 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 Xinjiang Agricultural Sciences is the property of Xinjiang Agricultural Sciences Editorial Department 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.)

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.)

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.)

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering 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.)

The planted floating bed is an innovative technology which consists of aquatic or terrestrial plants growing in a hydroponic manner with buoyant frames floating on the surface of waters. It is regarded as a low-cost, solar-energy-based and eco-friendly technology for in situ purification of surface water, and has been used all over the world as an important ecological remediation to control water eutrophication. At present, the conventional planted ecological floating bed body is generally made of natural materials and artificially synthesized materials. However, natural materials such as natural wood and bamboo are easy to rot and artificially synthesized materials such as synthetic polystyrene foam may easily cause secondary contamination if being long-term immersed in water. Porous ceramsite has high porosity and specific surface area which is in favor of absorbing microorganisms and is an ideal filtration material widely used in wastewater treatment. Biolog-ECO method has advantages over both classic cell culture techniques and molecular-level RNA (ribonucleic acid) amplification which has been widely used and shown to be a useful tool to detect differences in functional diversity of microbial populations in aquatic environments. In the present study, a novel type of floating bed carrier, which was mainly made of ceramsite functioned as a medium for biofilm growth and buoyant frames, was developed to remedy the water environment in the fishpond. Rice was planted on the floating bed functioned as nutrients assimilation species because it has strong anti-pollution and fast-growing abilities. The objective of the present study was to combine the rice hydroponic planting floating bed system and new floating bed carrier to develop an appropriate approach for the recycling of nitrogen and phosphate in the fishpond, and use it for eutrophic water remediation by studying the water quality purification efficacy and its effect on the metabolic activity and diversity of bacterioplankton in fishpond. The field experiments were carried out in 6 intensive fishponds in Jingzhou City, Hubei Province, China during the growing season in 2014. The results showed that the concentrations of total nitrogen (TN), total phosphorus (TP) and nitrite nitrogen (NO2--N) in the ponds employing the novel floating bed were significantly lower than that in the control ponds in August, and the permanganate index (IMn) was significantly lower in August and October. The metabolic pattern and diversity of bacterioplankton in the fishpond were analyzed by Biolog-ECO technique. The metabolic activity, which was indicated by average well color development (AWCD), Shannon diversity index and richness index in August and Shannon evenness diversity index in October, was significantly higher in the test ponds applying floating bed than that in the control ponds. The results indicated that the application of the novel floating bed changed the carbon source utilization pattern of the bacterioplankton communities in the intensive culture pond, and increased the metabolic activity and functional diversity of the bacterioplankton while controlled nitrogen and phosphorus nutrition level in the pond water. In addition, the rice absorbed nutrition directly from the fishpond water and formed biomass and gained a yield of 5 900 kg/hm2, which could provide extra profit. The results can provide a new approach for the regulation of water environment in aquaculture ponds, and provide valuable insight and theoretical guidance for controlling and optimizing the structure of bacterioplankton by applying the ecological engineering measures such as floating bed. [ABSTRACT FROM AUTHOR]

Jianghanplain area is characterized by plenty of rainfall in spring, which results in frequent occurrence of waterlogging of wheat field. Subsurface waterlogging is often found in these fields. It is necessary to investigate the influence of shallow groundwater table and waterlogging followed by submergence on the growth and yield and develop a suitable groundwater depth drainage index for the waterlogged fields. In order to achieve the objectives, tube-shaped concrete facilities were used for the irrigation and drainage adjustment experiment in 2014 and 2015. Wheat was planted in the facility. The treatment of shallow groundwater table at 0, 20, 40 and 60 cm sustained 18 d and different degrees of waterlogging followed by submergence were designed. The treatments were conducted in the booting and filling stages of wheat. The flooding depth in the waterlogging treatment was kept at 5 cm. Meanwhile, the facility for wheat cultivation in soil with moisture kept at 70%-80% of water holding capacity was used as a control. The results showed when the 0-cm groundwater table sustaining 18 d at booting and filling stage could reduce wheat yield by 44.78% and 67.72%, the 20-cm groundwater table sustaining 18 d could reduce the yield by 17.31% and 33.70%, the 40-cm groundwater table sustaining 18 d decreased the yield by 10.44% and 10.34% and the 60-cm groundwater table sustaining 18 d could had higher yield than the that under 100 cm, suggesting that the groundwater table kept at 50 cm at booting and filling stage of winter wheat was suitable. The yield reduction might be due to the decrease of kernels per and thousand seed weight. The regression showed that the yield could reach 95.1%-99.8% and 89.8%-96.9% of the control when the underground water depth was 40- 50 cm, it could reach 100% of the control when the underground water depth was 50.7 and 57.1 cm and it may slightly increase when the underground water depth was 60-80 cm. The wheat suffering from the damage of waterlogging followed by submergence after anthesis caused a severe reduction in wheat yield, and the surface waterlogging had the larger influence than subsurface waterlogging on yield of winter wheat. Different types of drainage indexes including surface and subsurface waterlogging duration days, sum of waterlogging or water table within 50 cm of soil surface, sum of both flood depth and water table within 50 cm of soil surface under surface waterlogging, sum of water table within 50 cm of soil surface after draining surface water logging, and comprehensive water depth of waterlogging were evaluated. The regression between relative yield and these indexes showed that the indexes with surface and subsurface waterlogging duration days, drainage model based on time classification and comprehensive water depth of waterlogging were reliable. If the wheat yield decrease by 15% was allowed, the comprehensive water depth of waterlogging should be 275.6-283.6 cm·d after anthesis. The research may provide support for wheat drainage management in booting and filling stage in the middle and lower reaches of the Yangtze River. [ABSTRACT FROM AUTHOR]

Cotton production is frequently limited by periods of subsurface waterlogging and heat stress in Hubei plain area of China in summer, but the combined effects of surface waterlogging and heat stress on cotton have been rarely studied. In order to investigate the effects of groundwater table (WT) on main morph-physiological traits and yield of cotton under high temperature (HT) condition as well as determination of drainage index, the combination of WT and HT stresses was carried out by test-pit in Irrigation and Drainage Experimental Station of the Four Lake Engineering Management Bureau, Jingzhou, China in 2012 and 2013. WT were set as 0, 30 and 50 cm with waterlogging for 10 days and HT duration for 6 days (from 10:00 to 16:00 per day) during flowering and boll-forming period of cotton. The morphological indexes as plant height (PH) and complex ratio of red stem to green stem (R/G), and physiological traits as photosynthetic efficiency, leaf pigments and antioxidant enzymes along with yield components were measured and analyzed. The results were as follows: the PH and R/G of cotton were decreased in WT treatments of 0 and 30 cm, whereas they were not significantly different in HT situation. Chlorophyll (Chl) content and photosystem II potential photochemical conversion efficiency of leaf (4 th from top) decreased with increasing WT under HT condition. The relationship of either Chl or photochemical conversion efficiency with WT and HT could be described by linear models (R2=0.961-0986, P<0.01). Superoxide dismutase (SOD) and peroxidase (POD) activities of leaves (4th from top) increased firstly and then declined and catalase (CAT) activity declined with the increment in WT, but malondialdehyde (MDA) content increased. SOD and POD activities decreased remarkably while MDA content increased rapidly at WT of 0-30 cm with HT stress, indicating that HT exacerbated the degree of membrane lid peroxidation. However, HT contributed to subsurface waterlogging tolerance by maintaining a higher SOD and POD activities at WT of 50 cm. The yield losses of the combination of WT and HT attributed principally to a reduction of boll numbers and boll quality. The reduction of seed yield was highest in the treatment of WT+HT (33.7%), followed by WT (26.2%) and HT (7.5%). Assuming the reduction of 15%-20% of seed yield was accepted, the sum of excess soil water of 80 cm (SEW80) during flowering and boll-forming period was 216.0-321.2 cm·d with 6 days of HT for WT 0-50 cm. The study may provide valuble information for cotton stress-resistance cultivation and drainage management in Hubei plain lake region of China. [ABSTRACT FROM AUTHOR]