Search

Nowadays, exploring new photonic materials that can efficiently convert the invisible light into the visible light have attracted tremendous attention in the catalytic field. Here, we design and prepare a kind of Bi 3+ doped Lu 2 CaGeO 6 phosphor by using the solid-state reaction at 1250 °C in air for 5 h. The structural analysis, which is based mainly on the powder X-ray diffraction (XRD) spectra, shows that the as-prepared Bi 3+ doped Lu 2 CaGeO 6 phosphors belong to a trigonal structure with a space group of R 3 (No. 146). The photoluminescence (PL) results reveal that changing the excitation wavelengths from 240 nm to 340 nm does not change the emission sharp and position of the Bi 3+ doped samples, allowing the maximum emission intensity to keep at 420 nm. Except for the fluorescence, up exposure to the UV light ( e.g. , 254 nm), the Lu 2 CaGeO 6 :Bi 3+ phosphors can also exhibit the Bi 3+ -related blue afterglow luminescence. The longest afterglow duration that corresponds to the 1.5%Bi 3+ doping content in the Lu 2 CaGeO 6 crystal host can last 30 min in the dark. After comparing the Bi 3+ -related blue afterglow band to the band gap of TiO 2 semiconductor that corresponds to the wavelength of 387 nm, it clearly indicates us that the Bi 3+ doped Lu 2 CaGeO 6 phosphors can serve as a continous excitation source for light-sensitive TiO 2 semiconductor for photocatalysis application. [ABSTRACT FROM AUTHOR]

Bardoxolone methyl, a synthetic triterpenoid, improves the estimated glomerular filtration rate (GFR) in patients with chronic kidney disease and type 2 diabetes. Since the contractile activity of mesangial cells may influence glomerular filtration, we evaluated the effect of the synthetic triterpenoid RTA 405, with structural similarity to bardoxolone methyl, on GFR in rats and on mesangial cell contractility in freshly isolated glomeruli. In rats, RTA 405 increased basal GFR, assessed by inulin clearance, and attenuated the angiotensin II-induced decline in GFR. RTA 405 increased the filtration fraction, but did not affect arterial blood pressure or renal plasma flow. Glomeruli from RTA 405-treated rats were resistant to angiotensin II-induced volume reduction ex vivo. In cultured mesangial cells, angiotensin II-stimulated contraction was attenuated by RTA 405, in a dose- and time-dependent fashion. Further, Nrf2-targeted gene transcription (regulates antioxidant, anti-inflammatory, and cytoprotective responses) in mesangial cells was associated with decreased basal and reduced angiotensin II-stimulated hydrogen peroxide and calcium ion levels. These mechanisms contribute to the GFR increase that occurs following treatment with RTA 405 in rats and may underlie the effect of bardoxolone methyl on the estimated GFR in patients. [ABSTRACT FROM AUTHOR]

Melatonin mediates multiple physiological processes in plants and is involved in many reactions related to the protection of plants from abiotic stress. In this paper, the effect of melatonin on the antioxidant capacity of rice under salt stress was studied. Melatonin alleviated the inhibition of salt stress on the growth of rice seedlings, mainly by increasing the dry weight and fresh weight of shoots and roots. Melatonin alleviated the membrane damage caused by salt stress, which was mainly manifested by the decrease of TBARS content and the decrease of leaf and root damage. During the whole salt stress period, rice after melatonin pretreatment showed lower ROS (H 2 O 2 , O 2 •−,OH−) accumulation. In the early stage (1–3 d) of stress, the rice after melatonin pretreatment showed a strong increase in antioxidant enzyme activity, while in the later stage (5,7 d), it showed a strong increase in antioxidant content. During the whole period of salt stress, melatonin had a weak regulatory effect on AsA-GSH cycle. Through the above regulation process, the decreasing effect of melatonin on ROS content of rice under salt stress did not decrease with prolonged stress time in a short time (1-7 d). In conclusion, melatonin improved the antioxidant capacity of rice under continuous salt stress, and rice showed variable antioxidant strategies after melatonin pretreatment. • Salt stress resulted in continuous accumulation of ROS, and MT pretreatment alleviated the oxidative damage of rice. • MT regulates antioxidant strategy in response to continuous salt stress. • MT pretreatment improves salt tolerance of rice. [ABSTRACT FROM AUTHOR]

Sucrose non-fermenting-1-related protein kinase 1 (SnRK1) plays a key role in rice germination. The small molecule drug, A-769662, activates AMP-activated protein kinase, a mammalian homolog of SnRK1. However, it is unknown whether A-769662 activates SnRK1, thereby affecting germination. SnRK1 in desalted extracts from germinating rice seeds was strongly activated by adding A-769662 in vitro. Applying 50 or 100 μM A-769662 accelerated germination and increased the root length, shoot length, and seedling fresh weight. 50 μM A-769662 treatment increased the catalytic activity and phosphorylation of SnRK1 during germination. Transcriptome analysis and biochemical validation were performed to investigate the mechanism whereby A-769662 treatment promoted rice germination. A-769662 treatment promoted starch hydrolysis by increasing the expression and activity of amylase and inhibited starch biosynthesis by decreasing the expression of OsAGPL2 , OsAGPS2a , Wx , and SSIIa. The abscisic acid (ABA) level and gene expression of ABA-induced transcription factors, including OsNF-YC9 , OsNF-YC12 , OsWRKY24 , OsPYL8 , OsMKKK62 , and OsMKKK63 , which reduced the inhibition of germination by ABA were decreased under 50 μM A-769662 treatment. The increased expression of the OsACO3 and OsACO5 genes and increased ethylene levels under A-769662 treatment, which counteracted the inhibition of ABA on germination and, thus, promoted germination. These results demonstrate the activation of A-769662 on SnRK1 and further reveal the regulatory mechanism of A-769662 in rice seed germination and nutrient remobilization. • AMPK activator, A-769662, strongly increases SnRK1 activity in vitro. • A-769662 treatment accelerates germination by affecting amylase gene expression, ABA pathway and ethylene biosynthesis. • SnRK1 may alter T6P level by regulating expression of TPP genes. [ABSTRACT FROM AUTHOR]

Monitoring crops with high spatio-temporal resolution satellites provides valuable observations to ensure food security in the global change context. This study focuses on estimating the Green Area Index (GAI) to monitor wheat crops with a spatial resolution of 3 m and daily satellite observations from the SuperDove constellation. With an easier access to large training datasets of ground GAI measurements, and the improvement of the realism of radiative transfer model simulations, the choice of the optimal approach (data-driven or model-driven) constitutes a key question when retrieving GAI from satellite observations. This study compares a data-driven and a model-driven approach to estimate GAI from the SuperDove satellites. Both approaches are based on Gaussian Process Regression (GPR) machine learning techniques. The data-driven approach uses over 300 ground GAI measurements collected from 12 sites in China and France, each with 20 to 51 contrasting plots. The model-driven approach uses 10,000 simulations of top of canopy reflectance and the corresponding GAI values generated by the LESS radiative transfer model applied to 3D scenes built with the ADEL-Wheat (Architectural model of Development based on L-systems) model. Results confirm that the SuperDove reflectance are reliable and consistent with Sentinel-2 values. When estimating GAI using GPR with SuperDove top of canopy reflectance, the model-driven approach (R2 = 0.83, RMSE = 0.80, Accuracy = 0.01 and Precision = 0.80) generally outperforms the data-driven approach (R2 = 0.80, RMSE = 0.88, Accuracy = −0.13 and Precision = 0.87), except for small GAI values. In-silico experiments show that the uncertainties in the ground-measured GAI and the size and diversity of the training datasets limit the data-driven approach. In contrast, the model-driven approach is mostly constrained by the realism of the reflectance simulations, particularly for low GAI values. Two ensemble solutions based on the weighted average of the two previous approaches are then proposed: the global ensemble solution (R2 = 0.86, RMSE = 0.75, A = −0.06 and P = 0.74) where the weight is assumed independent from the GAI values, and the adaptive ensemble solution (R2 = 0.85, RMSE = 0.76, A = −0.08 and P = 0.76) where the weight depends on the GAI values. Both solutions perform similarly, improving both data-driven and model-driven approaches. Finally, applying both solutions to monitor wheat plots along the growth cycle allows clear differentiation of nitrogen modalities and cultivar effects. However, a minimum plot size of 12 m × 12 m (4 × 4 pixels) is recommended to minimize the co-registration errors and increase estimate precision. • Data-driven and model-driven approaches for GAI retrieval of wheat from PlanetScope. • The model-driven approach outperforms the data-driven one except for low GAI values. • Both approaches were combined in an ensemble solution which improves GAI estimates. • The proposed methodology allows accurate and precise monitoring of wheat crops. [ABSTRACT FROM AUTHOR]

• Elevated temperatures affect structural parameters of starch chain length distribution. • Nitrogen decreased the height of fifth amylopectin peak that increased at elevated temperature. • Nitrogen increased the height of second amylose peak at elevated temperature. • Nitrogen changed pasting properties and decreased relative crystallinity under warming. Nitrogen fertilization can mitigate the negative effects of high temperatures on rice. In this study, we simulated dynamic field temperature increases using a free-air temperature enhancement system. Changes in the physicochemical properties of starch were investigated under increasing nitrogen fertilization during the grain-filling stage. We observed that the application of nitrogen at elevated temperatures (ETN) did not change the chain length distribution compared with elevated temperatures (ET) alone; however, it did significantly increase the heights of the first and second amylose peaks. Specifically, ETN significantly decreased the height of fifth amylopectin and relative crystallinity, and the changes it introduced in the physicochemical properties of starch were greater than those of ET. Overall, these changes in starch properties may be associated with the ability of nitrogen to facilitate the maintenance of rice quality at high temperatures. [ABSTRACT FROM AUTHOR]

Abstract: The peripheral arterial chemoreflex, arising primarily from the carotid body in most species, plays an important role in the control of breathing and in autonomic control of cardiovascular function. The peripheral chemoreflex is enhanced in heart failure patients and animal models of heart failure and contributes to the sympathetic hyperactivity and breathing instability that exacerbates the progression of the disease. Studies in animal models have shown that carotid body chemoreceptor activity is enhanced under both normoxic and hypoxic conditions in heart failure due to disruption of local mediators that control carotid body function. This brief review highlights evidence that the alterations in the gasotransmitters, nitric oxide, carbon monoxide, and hydrogen sulfide in the carotid body contribute to the exaggerated carotid body function observed in heart failure. [Copyright &y& Elsevier]

Melatonin (MT), an important antioxidant existing in plants and animals, has been widely reported to participate in the process of plants coping with stress. In this study, we demonstrated the mechanism of MT enhancing photosynthesis in rice under salt stress. The results showed that MT treatment increased relative water content, sucrose and starch content of rice under salt stress. This was mainly owing to the fact that MT enhanced the net photosynthetic rate and enhanced the absorption and transmission of light energy. The effect of MT on photosynthesis of rice under salt stress conditions was mainly due to the regulation of three processes: maintaining low ROS status by improving the total antioxidant capacity, promoting the xanthophyll cycle and increasing the xanthophyll pool size to dissipate excess light energy, increasing the activities of key photosynthetic enzymes. Taken together, these results provide a mechanism for MT to improve the photosynthetic capacity of rice under salt stress. • MT improved plant growth and photosynthetic products accumulation under salt stress. • MT increased the net photosynthetic rate and electron transport of rice under salt stress. • MT increased the xanthophyll cycle and activities of key photosynthetic enzymes, decreased the accumulation of ROS. [ABSTRACT FROM AUTHOR]

• Exogenous melatonin improves salt tolerance in rice seedlings. • Melatonin increases Na+ efflux and K+ influx in rice roots under salt stress. • Melatonin enhances the Na+/K+ homeostasis in rice under salt stress by increasing ATP content and H+-pump activity. • Melatonin increasing the root Na+/K+ transporters sensitivity to ROS/RNS. Salinity stress is one of the most serious factors limiting the productivity of crops. Rice at the seedling stage is extremely sensitive to salt. Studies have shown that melatonin can improve plant resistance to a variety of abiotic stresses, including salt stress. In this study, the mechanism of melatonin in regulating Na+/K+ homeostasis in rice seedlings was explored. The results showed that melatonin pretreatment increased rice dry weight and salt tolerance indices under salt stress. This is because melatonin inhibited the increase of Na+ content and the decrease of K+ content induced by salt stress and increased the ratio of K+/Na+. Melatonin increased the selective absorption indices of rice under salt stress, which indicated that melatonin pretreatment improved the ability of rice to absorb K+ and exclude Na+. The results of root Na+/K+ flux also confirmed this point. Rice pretreated with melatonin showed stronger roots Na+ efflux and K+ influx after salt stress. As signaling molecules, the content of nitric oxide increased in the roots of rice pretreated with melatonin, but the content of hydrogen peroxide decreased. Rice roots Na+/K+ transporters pretreated with melatonin were more sensitive to nitric oxide and hydrogen peroxide, which manifested as the Na+ efflux and K+ influx were stronger after being shocked by nitric oxide and hydrogen peroxide. This was due to melatonin pretreatment increasing roots' ATP content and H+-pump activity. These results indicated that exogenous melatonin could improve root Na+/K+ transporters' response to reactive oxygen species/reactive nitrogen species as well as increase ATP content and H+-pump activity to maintain Na+/K+ homeostasis in rice under salt stress. [ABSTRACT FROM AUTHOR]

[Display omitted] • Static magnetic field (SMF) could improve the frozen quality of rice dumpling. • SMF accelerated freezing rate and shortened phase transition of water. • SMF-assisted freezing restricted the transition of bound water to free water. • SMF-assisted freezing showed less damage on rice starch granules. • SMF-assisted freezing improved the physicochemical properties of rice flour. This study aimed to investigate the effect of static magnetic field (SMF, 0–10 mT) on the quality of rice dumplings subjected to 7, 14, 21, and 28 freeze–thaw cycles. The underlying mechanism was explored by monitoring changes in water phase transition, water distribution, and structural and physicochemical properties of rice flour. Results suggested that SMF enables the formation of small ice crystals by accelerating freezing rate, shortening phase transition time, and increasing bound water content, which attributes to reducing the mechanical damage on starch granules and thus improves the quality of frozen rice dumpling. After 7–28 freeze–thaw cycles, SMF treatment increased the whiteness by 0.08–1.58, reduced the cracking ratio by 1.67 %–8.34 %, decreased the water loss ratio by 0–0.75 %, and significantly improved the texture of cooked rice dumplings. This study confirmed the feasibility of SMF in improving the quality of rice dumpling, which contributes to expanding the applications of magnetic freezer in the preservation of starch-based foods. [ABSTRACT FROM AUTHOR]

The redistribution of nonstructural carbohydrates (NSCs) in rice (Oryza sativa) sheaths contributes greatly to grain filling. Sucrose nonfermenting-1-related protein kinase 1 (SnRK1) regulates sheath-to-panicle transport of NSCs during rice grain filling; however, it is unknown whether elevated activity of SnRK1 in sheaths improves NSC transport and grain filling. Expression of OsSnRK1a is mainly responsible for regulating SnRK1 activity in rice sheaths. Analysis of transgenic rice plants containing the OsSnRK1a promoter::GUS construct indicated that OsSnRK1a is widely expressed in rice. Notably, OsSnRK1a is highly expressed in mesophyll cells of sheaths. Therefore, a green tissue promoter specifically expressed in sheaths and leaf parenchyma cells and phloem tissue was used to over-express OsSnRK1a in japonica rice. The transgenic lines exhibited increased SnRK1a expression and SnRK1 activity in sheaths. The NSC and starch in the transgenic lines and WT all showed accumulation before heading and during the early-filling stage, and declining at the peak filling stage. But the starch and NSC content in transgenic lines was lower than that of WT. Moreover, the transgenic lines showed lower sucrose contents and higher sucrose efflux rates. The accelerated sheath NSC transport improved grain filling, and stimulated panicle development in transgenic lines. SnRK1a expression and SnRK1 activity were also increased in the leaves of transgenic lines, which improved leaf photosynthetic activity and contributed to optimal grain filling and panicle development. These results verify the promotion of high SnRK1 activity in sheath NSC transport, and also provide a new approach to improving sheath NSC transport and rice yield. • OsSnRK1a is highly expressed in mesophyll cells of sheaths. • The PP promoter was used increased SnRK1a expression and SnRK1 activity in sheaths of transgenic lines. • Elevated SnRK1 activity in sheaths accelerated NSC transport in transgenic lines, thereby improving grain filling and final yield. • SnRK1 activity and the photosynthetic rate were also increased in leaves of the transgenic lines. [ABSTRACT FROM AUTHOR]

Rice glutelin is sensitive to temperature and nitrogen, however, the regulatory mechanism of glutelin response to temperature and nitrogen is unclear. In this study, we conducted the open field warming experiment by the Free-air temperature enhancement facility and application of nitrogen during grain filling. In three-year field warming experiments, glutelin relative content was significantly increased under elevated temperature and application of nitrogen. Temperature and nitrogen and their interaction increased the glutelin accumulation rate in the early and middle grain filling stages (10-25d after flowering), but decreased the glutelin accumulation rate in the middle and late grain filling stages (25-45d after flowering). Elevated temperature promoted pro-glutelin levels whereas application of nitrogen under warming increased the amount of α-glutelin. At the transcriptional level, the expression levels of the glutelin-encoding genes and protein disulphide isomerase-like enzyme (PDIL1-1), glutelin precursor accumulation 4 (GPA4), glutelin precursor mutant 6 (GPA2), glutelin precursor accumulation 3 (GPA3) and vacuolar processing enzyme (OsVPE1) of glutelin folding, transport and accumulation-related genes were up-regulated by nitrogen under natural temperature as early as 5d after flowering. However, elevated temperature up-regulated glutelin-encoding genes before 20d after flowering, and the expression of endoplasmic reticulum chaperone (OsBip1), OsPDIL1-1 , small GTPase gene (GPA1), GPA2-GPA4 and OsVPE1 were significantly increased post 20d after flowering under warming. In addition, the increase in glutelin content worsened grain quality, particularly chalkiness and eating quality. Overall, the results were helpful to understand glutelin accumulation and provide a theoretical basis for further study the relationship between rice quality and glutelin under global warming. • Elevated temperature and additional nitrogen and their interaction significantly increased the glutelin relative content. • Temperature and nitrogen and their interaction increased the glutelin accumulation rate in the early and mid-filling periods. • Elevated temperature promoted the level of pro-glutelin whereas further additional nitrogen improved the level of α-glutelin. • Glutelin synthesis and maturity were regulated by elevated temperature at 5-20d and 20-30d after flowering, respectively. [ABSTRACT FROM AUTHOR]

Highlights • Increased temperature affects starch anabolism and further affected quality traits. • Under elevated temperature, nitrogen decreased the starch particle-size induced chalky rice. • Nitrogen regulates starch structure to further affect quality under elevated temperature. • Adjusting nitrogen fertilizer use likely mitigates quality deterioration under climate warming. Abstract Relevant evidence of rice quality responses to increased temperatures under field condition has been obtained in our previous study. Understanding the intrinsic mechanism of increased temperatures and fertilizer treatment in regulating rice quality formation will be contributed to the development of mitigation measures suitable for actual field operations and to cope with climate warming. This study investigated the potential role of nitrogen fertilizer in regulating the rice quality under field warming through identifying starch-related property indicators. Results showed application of nitrogen fertilizer at heading stage effectively delayed the significantly increased accumulation of total starch, amylose and amylopectin, and reduced the starch particle size, chain length distribution, and crystal structure induced by high temperature, which further compensated the deterioration of rice quality caused by elevated temperature. [ABSTRACT FROM AUTHOR]

In the Taihu region of China, overuse of chemical nitrogen (N) fertilizer is often associated with low nitrogen recovery (NRE) and leads to serious groundwater pollution caused by N leaching losses. Controlled-released nitrogen fertilizers (CRNFs) and mechanized deep placement are promising alternatives to broadcasting urea to increase crop yield and NRE in machine-transplanted rice production. However, their interactions with regard to soil N status, N leaching and crop performance are unclear. A two-year (2015 and 2016) field experiment was conducted in a randomized complete block using two fertilization techniques (broadcast and deep placement by mechanical side-dressing fertilization) and three CRNFs (sulphur-coated urea (SCU), polymer-coated urea (PCU) and a bulk blended mixture (BBF)). Conventional high-yield fertilization (four split applications of urea at 216 kg N ha −1 (CK)) and 0–N treatments were established as controls. The results showed that the variation in NH 4 + -N concentration in the percolation and surface water varied across the different CRNFs, irrespective of the techniques used. NO 3 − -N concentration in the percolation water varied with water conditions in the field. Deep placement with CRNF correspondingly increased mineral N concentration in percolation at depths of 20 and 60 cm but reduced it in the surface water compared to that of the broadcast, although the benefits varied depending on the CRNF type and growth stage. Deep placement of SCU and PCU significantly increased N leaching and the mineral N in the 40–60 cm soil layer compared to that of the broadcast, due to the intensive N release during tillering and ineffective stage when the rice plant had a weak N uptake capability. Deep placement of SCU had the highest N leaching of 6.65 and 5.34 kg N ha −1 during 2015 and 2016. In contrast, BBF exhibited the lowest N leaching, regardless of fertilization placement, which apparently synchronized N release rates with rice N uptake patterns. In the present study, BBF obtained higher rice yields and N recoveries, without significantly enhancing mineral N leaching losses, when compared to CK. Our results suggest that the use of BBF is a promising alternative to a conventional high-yield fertilization practice, especially if combined with deep placement. [ABSTRACT FROM AUTHOR]

The adverse impacts of climate warming on rice production have become increasingly evident. In this regard, although our previous field studies enabled us to establish the positive impacts of nitrogen fertilizer on rice grain yield during warming, it remains necessary to clarify whether nitrogen fertilizer under elevated temperatures has any adverse effects on the environment during the grain-filling stage. To further investigate the impacts of nitrogen fertilizer on rice yield and the associated emissions of methane (CH 4) and nitrous oxide (N 2 O) under elevated temperatures, we conducted a 2-year paddy field study using a free-air temperature enhancement (FATE) system. FATE system had a favorable warming effect on the canopy and soil, and greatly decreased grain yield by 23 % on average. In two trial years, elevated temperatures significantly increased in CH 4 emissions by 17.7 kg ha−1and 18.9 kg ha−1, but did not affect N 2 O emissions. Consequently, we detected significant increases in global warming potential (GWP) by 52 % and 19 % and greenhouse gas intensity (GHGI) by 94 % and 56 % under elevated temperatures in 2019 and 2020, respectively. Although nitrogen fertilizer had no significant influence on CH 4 emissions under elevated temperatures, N 2 O emissions significantly increased by 1.5 kg ha−1 and 1.4 kg ha−1 in 2019 and 2020. Nevertheless, nitrogen fertilizer did not affect GWP and significantly decreased GHGI by 10 % under elevated temperatures in 2020. Additionally, elevated temperatures significantly increased the abundance of methanogens (mcrA), ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA), and nitrous oxide reductase (nosZ) genes. Whereas, nitrogen fertilizer significantly increased nitrite reductase (nirS) gene abundance under elevated temperatures. In conclusion, our findings indicated that 60 kg N ha−1 at the heading stage could effectively alleviate the reduction in grain yield attributable to elevated temperatures, without increasing GWP, thereby enhancing the economic and environmental sustainability of paddy field system. • Warming had no impact on N2O emissions but significantly increased CH4 emissions. • Nitrogen fertilizer had no significant impact on CH4 emissions under warming. • Nitrogen fertilizer did not affect global warming potential under warming. [ABSTRACT FROM AUTHOR]

Global warming often affects crop yield and greenhouse gas emissions from cropland. However, the effects of warming on rice yield and methane (CH 4) emissions from rice paddies in the tropical double-rice cropping systems are still unknown. Therefore, we conducted a field experiment to investigate the effect of warming on rice growth and CH 4 emissions in a Chinese tropical double-rice cropping system, using the free air temperature increase facility. The results showed that warming did not affect the rice plant biomass, but significantly reduced the early rice yield by 5.0% and late rice yield by 6.5%. Warming trended to increase CH 4 emissions, especially in the flooded stage of early rice seasons. Warming significantly stimulated the abundance of methanogens and methanotrophs, and CH 4 production and oxidation potential by 93.3%, 84.3%, 29.3% and 66%, respectively. Warming non-significantly increased the soil dissolved organic carbon concentrations, but significantly reduced the soil NH 4 + concentrations. Warming significantly increased yield-scaled CH 4 emissions by 7–41%. Our findings suggest that warming may reduce rice yield but increase CH 4 emissions from the Chinese tropical double-rice cropping systems and underline the need for agricultural practices of higher rice yield and lower CH 4 emissions. • The study was conducted in a Chinese tropical double-rice system. • Warming trended to increase CH 4 emissions, especially in the flooded stage. • Warming increased the abundances of methanogens and methanotrophs. • Warming significantly reduced rice yield and increased yield-scaled CH 4 emissions. [ABSTRACT FROM AUTHOR]

Soil organic matter (SOM) in paddy soils is critical for sustainably achieving high crop yields, especially in the face of ever-intensifying anthropogenic climate change. Our previous studies showed that long-term fertilizer postponing (FP) sustainably increases rice yields by improving SOM via residual carbon input. However, the effect of C release from living roots on SOM under a long-term FP regimen remains unclear. Therefore, in this study, rice plants were subjected to 13CO 2 pulse labelling at the panicle initiation (PI) and heading stage (HS). PI-labelled plants were destructively sampled 6 h after labelling, during spikelet differentiation, and when they reached maturity; on the other hand, HS-labelled plants were sampled 6 h after labelling and during the final harvest. The results showed that FP did not affect the ability of plants to assimilate photosynthetic C at PI and HS; however, it significantly reduced the loss of assimilated C at PI. 13CO 2 loss was significantly and positively correlated with the microbial biomass [13C-phospholipid-derived fatty acid (PLFA) content] and microbial community composition. After 6 h of 13CO 2 labelling at PI, the total 13C-PLFA content of FP was significantly reduced by 51.2% than that of conventional fertilizer (CF). This was mainly because FP reduced the dominant microbes [i.e., G− (α15:0 and α17:0) and G+ (16:1ω7c) bacteria] that utilize assimilated 13C. The 13C-PLFA content of FP was significantly higher than that of CF from 6 h of 13CO 2 labelling at HS to harvest, mainly because FP increased the dominant fungi (18:1ω9c, 20:1ω9c) that utilize assimilated C. Redundancy analysis revealed that microbes using assimilated C at the PI and HS were regulated by soil soluble organic nitrogen and total nitrogen, respectively. Overall, our findings suggest that long-term FP reduced assimilated C loss by reducing the G− and G+ bacterial content at PI and altered the microbial community structure at HS to increase the soil's carbon sequestration potential by increasing the fungal content. Concept map of carbon sequestration in photosynthetic carbon under long-term fertilizer postponing. [Display omitted] • Long-term fertiliser postponing (FP) did not affect photosynthetic carbon assimilation. • Long-term FP reduced the loss of assimilated carbon. • G+ (16:1ω7c, 18:1ω7c) and G- (α15:0, α17:0) bacteria caused assimilated carbon loss. • FP increased C sequestration potential by increasing fungi contents. [ABSTRACT FROM AUTHOR]

Lodging is a major limiting factor for grain yield and quality, and low light enhances lodging risk by increasing stem elongation and decreasing culm thickness. This study evaluated the effect of exogenous uniconazole (UCZ) on the basal stem physiological mechanism, cell structure, carbohydrates, and lignin-related enzymes in culm tissue under shading conditions. The results showed that shading stress significantly decreased grain yield and stem mechanical strength in 2020 and 2021. Compared with normal light (CK), shading rapidly decreased the breaking strength (M) and section modulus (SM). Exogenous UCZ increased culm wall thickness and improved lodging resistance. Uniconazole application also reduced plant height, gravity height, and second basal internode length by inducing a reduction in the cell length, and caused the cells to be densely arranged under both normal light and shading conditions. Scanning electron microscopy (SEM) revealed that the thickness of the sclerenchyma tissue cell wall increased under both conditions under the UCZ treatment, which induced an increase in the cell wall content. Uniconazole application significantly increased non-structural carbohydrate, lignin, cellulose, and hemicellulose contents in culm tissue. Moreover, UCZ application regulated lignin-related enzymes, such as phenylalanine ammonia-lyase (PAL), 4-coumarate: CoA ligase (4CL), cinnamate 4-hydroxylase (C4H), laccase (LAC) and peroxidase (POD). Thus, exogenous UCZ could enlarge sclerenchyma cell wall thickness, alter cell morphology in the stem, and increase stem strength by increasing carbohydrate content, including non-structural carbohydrates, cellulose, lignin, and hemicellulose, to enhance rice (Oryza sativa L.) lodging resistance under shading conditions. • Shading stress altered slender and loose cell arrangement in the parenchyma tissue of the second basal internode. • Uniconazole enhances lodging resistance of Japonica Rice by increasing sclerenchyma cell wall thickness. • Lignin accumulation and activities of lignin-related enzymes were increased by uniconazole. [ABSTRACT FROM AUTHOR]

Recently, a novel controlled-release N fertiliser (CRNF) application method using basal CRNF combined with urea top-dressing at the tillering stage has been proposed to enhance rice yield and N use efficiency (NUE). However, its effect on ammonia volatilisation (AV) loss and the yield and NUE of blanket-seedling machine-transplanted rice are unknown. A field experiment was performed to investigate the effect of three types of CRNF (slow-release blending fertiliser (BSRB), polymer-coated urea (PCU) and sulphur-coated urea (SCU)) and two fertilisation regimes (a single basal application (B) and a basal CRNF application combined with urea top-dressing at the tillering stage (BT)) on grain yield, NUE and AV loss from paddy soil of blanket-seedling machine-transplanted rice. Conventional high-yield fertilisation (four split applications of urea at 270 kg N ha −1 (CK)) and 0-N treatments were established as controls. The results demonstrated that the AV flux values from paddy soil varied in distinct patterns for the different CRNF treatments. The cumulative AV loss in the urea treatment during the basal (the first week) and tillering fertiliser (the second week) comprised the majority of the total AV loss, both accounting for 87.2% in each year. Compared with CK, B-BSRB significantly reduced AV loss during the first two weeks and the total AV loss by 24.7% and 27.9% in 2013 and 2014, respectively. B-SCU and B-PCU generally showed no benefits for reducing AV loss relative to urea. Compared with B-PCU and B-SCU, B-BSRB met the N demand of rice, substantially mitigated N loss via AV in paddy fields, and improved yield and NUE of Blanket-seedling Machine-Transplanted rice. The effect of BT for each CRNF on AV loss was not consistent. The BT-BSRB and the BT-SCU correspondingly mitigated AV loss to a certain extent in each year, mostly due to the relatively lower AV loss during the first week, and no significant increase in AV loss at the second week. The BT-BSRB incurred not only the lowest AV loss of 39.7 kg N ha −1 and 37.8 kg N ha −1 but also the highest yield of 11.6 t ha −1 and 10.1 t ha −1 and an NRF of 48.8% and 52.4% in 2013 and 2014, respectively. Our results suggested that combining BSRB and BT optimised rice yield and nitrogen use efficiency while decreasing ammonia volatilization from paddy soil of blanket-seedling machine-transplanted rice. [ABSTRACT FROM AUTHOR]

Rice ( Oryza sativa L.) and wheat ( Triticum aestivum L.) are two stable food crops that play a vital role in national food security. Summer rice-winter wheat double-cropping rotation is the dominant crop rotation practice used in the middle-lower Yangtze River region of China. However, excessive application of nitrogen (N) fertilizer in this region has led to low nitrogen use efficiency (NUE). To our knowledge, no studies have investigated the effects of reducing N fertilizer applications during both the rice and wheat seasons on crop yield, NUE, and soil fertility. In this study, we conducted a two-year field experiment using N fertilizer rates of 180, 240, and 300 kg N ha −1 during the rice growing season and 135, 180, and 225 kg N ha −1 during the wheat growing season. No differences in yield were observed among the treatments during the rice growing season; however, reduced N fertilizer application significantly affected yield during the wheat growing season. Reducing the amount of N fertilizer applied during the previous season and current season and the interactions between these seasons (R × W) had no effect on rice yield but did affect wheat yield. In addition, the N application rates significantly influenced N uptake and NUE. During the rice growing season, the N agronomic efficiency (NAE), N physiological efficiency (NPE), N partial factor productivity (NPF), and N recovery efficiency (NRE) increased by 20.6–42.5%, 11.1–15.8%, 23.9–40.2%, and 4.8–28.2%, respectively. During the wheat growing season, the NAE, NPE, NPF, and NRE increased by 20.4–54.9%, 8.2–16.5%, 21.8–58.3%, and 11.6–24.4%, respectively. We applied 15 N-labelled urea in the remainder of the soil N fertilization treatments, which indicated that the addition of 15 N fertilizer resulted in no difference in the 0–60 cm soil profile after rice harvest. Collectively, reducing N fertilizer application rates can effectively improve NUE and decrease N losses, and short-term reductions in N fertilizer application do not affect soil fertility. [ABSTRACT FROM AUTHOR]

Soil organic matter (SOM) in paddy soils is critical for achieving high crop yield sustainability and mitigating climate change. Our previous study revealed that long-term fertilizer postponing (FP) increases yield by improving SOM. Therefore, in this study, the mechanism by which fertilizer postponing increase SOM were investigated through a long-term experiment (11 years). Long-term FP significantly increased SOM (by 14.5%) by increasing root residue input. FP increased soil phenol oxidase activity and peroxidase activity but did not affect β-glucosidase activity, indicating that FP accelerated lignin degradation rather than cellulose degradation. Metagenome analysis also showed that FP significantly increased the relative abundance of lignin degradation genes, such as soil catalase, cytochrome c peroxidase, and peroxidase genes, by activating the growth of related microorganisms. In addition, long-term FP significantly increased bacterial necromass C (by 17%) and fungal necromass C (by 13%) by improving microbial biomass. Redundancy analysis and random forest model further revealed that lignin degradation genes (representing the contribution of lignin) and bacterial necromass C were dominant in plant- and microbe-derived C, respectively. We confirmed that the soil NH 4 +-N content was the main driving factor for high lignin degradation and microbial necromass variation. Structural equation model and random forest model revealed that soil carbon sequestration was mainly through the increase of lignin degradation and microbial necromass under high root residues input and soil NH 4 +-N content. Overall, our findings suggest that long-term FP is a sustainable agricultural management strategy that improves SOM by accelerating lignin degradation and increasing microbial necromass. • Long-term fertilizer postponing increases organic matter via root residue input. • Fertilizer postponing accelerates the growth of lignin-degrading microorganisms. • Fertilizer postponing increases microbial (especially bacterial) necromass C. • Soil NH 4 +-N significantly regulates carbon sequestration pathways in paddy. [ABSTRACT FROM AUTHOR]

The effects of four levels of panicle nitrogen fertilizer on the grain filling characteristics of three rice ( Oryza sativa L.) varieties (super japonica rice Ningjing 3, three-line japonica hybrid rice Changyou 3 and three-line indica–japonica hybrid rice Yongyou 12) were analyzed. The results showed that difference in time of maximum filling rate ( T max ) was the smallest between the superior and inferior spikelets of Ningjing 3, bigger between those of Changyou 3, the biggest between those of Yongyou 12. Ningjing 3 was of the synchronous grain-filling type, Yongyou 12 the asynchronous type, and the Changyou 3 the medium type. The grain filling rate, the initial filling power ( R 0 ), the maximum filling rate ( G max ), and the average filling rate ( G ) of the superior and inferior spikelets of the three varieties under the treatment of panicle N with the amount of 120 kg ha −1 (middle panicle N, shortened as NM) treatment were higher than those of other treatments. NM treatment led to the highest increase in grain weight at the middle stage of filling for all the three varieties. The treatment shortened the early and late stages of grain filling, but extended the middle stage when the filling rate was the highest. However, the middle stage of grain filling of Changyou 3 and Yongyou 12 was much more extended than that of Ningjing 3, indicating a better effect of N on hybrid rice varieties. [ABSTRACT FROM AUTHOR]

Background and aims The main objectives of this paper were to investigate the absorption and utilization of nitrogen applied at the panicle stage in rice for promoting and protecting spikelet and the effect of residual nitrogen on the utilization of nitrogen in the succeeding wheat crop in the rotation system. Methods A field experiment was combined with a mini-plot experiment with 15 N labelled urea applied at the panicle stage in rice. The experiments included three nutrient management treatments: F, S1 and S2. 126 kg N ha −1 , 120 kg N ha −1 , 72 kg N ha −1 labeled with 30 atom% excess 15 N were applied in rice, respectively. Results (1) Compare to conventional fertilizer management (F), the optimized fertilizer management (S1&S2) reduced the amount of nitrogen applications, whereas the rice and wheat yield did not decrease, and nitrogen use efficiency was improved. (2) At rice harvest, 4.7–10.7% of the fertilizer 15 N was found in the 0–20 cm profile. The fertilizer 15 N absorbed by the wheat during the period from jointing to heading accounted for 37.0%-51.1% of the total 15 N absorbed. (3) The sum of the ratio of nitrogen absorption from the rice panicle fertilizer applied to the crops (rice and wheat) and ratio of soil residue nitrogen in the wheat field were ordered S2 > S1 > F. Conclusion The optimized fertilization management reduced the loss of the rice nitrogen in the rice–wheat rotation system through improved recycling of rice panicle nitrogen applied in the crop-soil system. [ABSTRACT FROM AUTHOR]

Atmospheric CO 2 concentrations and water management practices both affect greenhouse gas (GHG) emissions from rice paddies, but interactive effects between these two factors are still unknown. Here, we show the first study to compare the impact of elevated atmospheric CO 2 (eCO 2) on GHG emissions under continuously flooded irrigation (CF) and under intermittently flooded (IF) conditions. Elevated CO 2 stimulated CH 4 emissions under CF by 50% in a field experiment and by 46% in a pot experiment, but it had no effect under IF in both experiments. Elevated CO 2 had no effect on N 2 O emissions in either the field or pot experiment. Rice root biomass, aboveground biomass and grain yield increased with eCO 2 , but were not affected by water management. Elevated CO 2 only stimulated the abundance of methanogens under CF, suggesting that increased soil O 2 availability with IF limited methanogenic activity under eCO 2. Our findings suggest that estimates of CH 4 emissions from global rice agriculture with eCO 2 need to account for recent changes in water management. • The first study to compare the effect of elevated CO 2 on GHG emissions under CF and IF. • Elevated CO 2 stimulated CH 4 emissions under CF, but had no effect under IF. • Elevated CO 2 did not affect N 2 O emissions under CF and IF. • Elevated CO 2 increased the abundance of methanogens under CF only. • Current estimates of CO 2 effects on CH 4 emissions from rice paddies may be too high. [ABSTRACT FROM AUTHOR]

Highlights: [•] Differences of rice lodging affected by nitrogen (N) under different eco-sites were significant. [•] For the lower lodging index (LI) rice populations, N primarily decreased the stems stiffness. [•] For the higher LI rice populations, N mainly impacted the morphological parameters of the basal stems. [ABSTRACT FROM AUTHOR]

Highlights: [•] We simulated low emission scenario (B1) of global warming in rice paddies. [•] Day, night and dield warming treatments were imposed. [•] Impact of nighttime warming was greater than the daytime warming. [•] Greater reduction in head rice recovery under nighttime warming than the daytime warming. [•] Rice hybrids tested showed varying degree of susceptibility to day and night warming. [ABSTRACT FROM AUTHOR]

A three-year experiment was conducted in the middle-lower reaches of the Yangtze River in China to study the influence of continuous wheat straw return during the rice season and continuous rice straw return in wheat on methane (CH 4 ) emissions from rice fields in which, the rice-wheat rotation system is the most dominant planting pattern. The field experiment was initiated in October 2009 and has continued since the wheat-growing season of that year. The analyses for the present study were conducted in the second (2011) and third (2012) rice growing seasons. Four treatments, namely, the continuous return of wheat straw and rice straw in every season (WR), of rice straw but no wheat straw return (R), of wheat straw but no rice straw return (W) and a control with no straw return (CK), were laid out in a randomized split-plot design. The total seasonal CH 4 emissions ranged from 107.4 to 491.7 kg/ha (2011) and 160.3 to 909.6 kg/ha (2012). The increase in CH 4 emissions for treatments WR and W were 289% and 230% in the second year and 185% and 225% in the third year, respectively, in relation to CK. We observed less methane emissions in the treatment R than in CK by 14%–43%, but not statistically significant. Treatment R could increase rice productivity while no more CH 4 emission occurs. The difference in the total CH 4 emissions mainly related to a difference in the methane flux rate during the first 30–35 days after transplant in the rice growing season, which was caused by the amount of dissolved oxygen in paddy water and the amount of reducible soil materials. [ABSTRACT FROM AUTHOR]

One of the major challenges facing rice breeding is to produce ideotype or ideal plant architecture (IPA) to improve canopy radiation use efficiency and hence grain yield. The hybrid japonica rice Jiayou Zhongke 6 (JYZK-6) is one of the benchmark cultivars with IPA characteristics, but the physio-ecological foundation of its high yield potential is still imperfectly understood. In this study, two-year field experiments were conducted using four japonica rice cultivars including JYZK-6 with contrasting canopy structures. A dynamic canopy light interception simulating device was constructed to capture canopy images representing the diurnal dynamics of solar angles throughout the grain-filling stage. Subsequently, leaf to panicle ratio (LPR), a newly developed physiological trait indicative of source-sink relations, was exploited to quantify the light distribution pattern within the rice canopy. The LPRs with high spatio-temporal resolution clearly showed the diurnal changes of light interception within the rice canopy. Genotypic differences in diurnal pattern of LPR were detected among the tested cultivars in both growing seasons, with the amplitude varying with grain-filling stages. Notably, LPR of the IPA cultivar JYZK-6 and its analogue WYJ-29, had a pattern of a V-shaped graph, peaking at sunrise and sunset while dropping to the lowest at noon during middle and late stages. Morphological measurement showed that the V-shaped pattern was associated with the height difference between flag leaf and panicle, panicle curvature, ratio of leaf area to panicle area, as well as the changing solar angles along with the progression of growth stage. This distinguishing feature of light pattern indicates that within the canopy of IPA cultivars, the leaf receives more light in the morning and afternoon whereas the panicle harvests more light at noon. It is inferred that such novel characteristics may provide the IPA cultivar with advantages of reducing midday suppression over the conventional cultivars, while more work is needed to verify this hypothesis. In summary, findings of this study offer a deeper insight into the physio-ecological processes underpinning radiation use efficiency at canopy level, and hence are valuable for breeding programs for ideotype cultivars. • A simulating device was constructed to capture canopy RGB images representing the diurnal dynamics of solar angles. • Leaf to panicle ratio (LPR) was exploited to quantify the light distribution pattern within the rice canopy. • LPR of the ideal plant type (IPA) cultivar JYZK-6 had distinguishing light pattern of a V-shaped graph. • The V-shaped pattern was associated with the morphology of the flag leaf and panicle, and the height difference between them. [ABSTRACT FROM AUTHOR]

Abstract: A number of field studies have reported very high rice yields in Taoyuan, Yunnan province, China, and the physiological and ecological factors associated with high yield have been explored. However, little attention has been paid to differences in plant type. The main objective of this study was to reveal the plant type characteristics associated with the high rice yield through the comparison of two sites: Taoyuan, Yunnan province and Nanjing, Jiangsu province, China. The physiological and environmental factors were also discussed. Field experiments were conducted at two sites in 2006 and 2007. Three Indica F1 hybrid varieties, Eryou 107, Xieyou 107 and Eryouhang 1 in 2006, Eryou 107 and Xieyou 107 in 2007 were grown at two sites under optimum crop management to achieve maximum attainable yields. Leaf area, leaf length, leaf width, leaf angles, specific leaf weight (SLW) and specific leaf nitrogen (SLN) at heading, yield and yield components at maturity were determined. Daily radiation, air temperature and relative humidity (RH) were monitored. The highest yield of 18.5tha−1 was achieved by Eryou 107 at Taoyuan in 2006, and average yield of all varieties at Taoyuan was 96% and 85% higher than Nanjing in 2006 and 2007, respectively. The higher yield at Taoyuan was attributed primarily to the larger sink size, which was mainly caused by the greater number of panicles per m2. Biomass production was greater at Taoyuan than at Nanjing in 2006 and 2007, while differences in harvest index were very small. Compared with Nanjing, the rice planted in Taoyuan has greater leaf area index about 10 with smaller area per stem, shorter, wider and thicker leaves and smaller leaf angles. These results indicate that in addition to the higher biomass accumulation (main physiological factor) and the intense solar radiation with the large diurnal temperature range (main environmental factor), the greater leaf area index (LAI) with smaller area per stem, may be an important morphological factor contributing to the high yield in Taoyuan. [Copyright &y& Elsevier]

• We investigated the dynamics of internode dry matter (DM) from 21 days before anthesis to maturity for japonica rice. • We found a sharp reduction of internode DM between 20 and 30 days after anthesis (DAA). • Non-structural carbohydrates in internodes were significantly remobilized between 20–30 DAA. • A marked increase in internode DM at maturity was detected. • Internode DM can be viewed as an integrative index for source-sink balance. Storage of non-structural carbohydrates (NSC) in internode parenchyma before anthesis functions as a major carbon source for rice grain filling. In this study, two-year field and pot experiments with three japonica cultivars and two nitrogen (N) fertilization modes were performed, and dynamics of dry matter (DM) in internodes were quantified from 21 day before anthesis (DBA) to 60 day after anthesis (DAA; maturity). Results showed that in comparison to leaves and sheaths, DM in internodes varied dramatically, with a clear pattern of increasing at 21 DBA, peaking at 10 DAA, then dramatically dropping until 20 or 30 DAA, and finally refilling at maturity. The sharp reduction of dry matter in the internodes corresponded with the fastest rate of grain filling, indicating the importance of internode reserves for yield formation. On the other hand, the high rate of refilling in internodes at late stage implies the excess production of leaf photosynthetic assimilates. Similarly, starch content in internodes showed a pattern of decreasing at 20–30 DAA. To clarify the indicative meaning of internode reserves, we calculated their remobilization rate at 20 DAA and refilling rate at 60 DAA. Genotypic variations existed for the three cultivars, with a range of 15.17 %–36.37 % for remobilization rate and 54.36 %–104.33 % for refilling rates in 2018. Overall, N topdressing significantly increased the translocation of internode reserves for all three cultivars. Furthermore, our calculation showed that only about 10 % of the grain yield was formed during the second month of rice grain filling, indicating this period is less important for grain yield. Our findings help to clarify the significance of internode DM dynamics for rice management and should be beneficial to enhance our knowledge of source and sink relations, the fundamental component of crop yield formation. [ABSTRACT FROM AUTHOR]

• Climate warming was simulated by a field-warming system in an actual rice field. • Intensified cultivation measures were developed to increase spikelet fertility and grain quality under heat stress. • Further efforts on improving fertilization to eliminate heat injury on rice using intensified measures are recommended. Heat induces spikelet sterility during flowering in rice. Spikelet sterility in heat-stressed plants is associated with poor pollination due to insufficient pollen grain deposition and unsatisfactory fertilization from reduced pollen germination on the stigma. Measures aimed at facilitating pollen shedding and pollen germination will help to address the adverse effects of heat stress on spikelet fertility in rice during the flowering stage. Intensified pollination by artificially assisted pollen shedding combined with intensified fertilization by promoting pollen germination through chemical application (pH=8.0, 10 % sucrose, 0.1 mM spermidine, 0.01 % myo-inositol, 0.01 % boric acid, 1 μM 24-epibrassinolide, 1 mM KCl, 1 mM CaNO 3 , 1 mM CaCl 2 , 0.03 % casein enzymatic hydrolysate, 0.01 % ferric ammonium citrate, 10 mM γ-aminobutyric acid, and 1–2 drops of Tween 20) increased spikelet fertility significantly compared with that without intensified measures under heat treatments in controlled greenhouse conditions. Intensified pollination increased the percentage of anther dehiscence and the number of pollen grains on the stigma, and the chemical application increased the number of germinated pollen grains on the stigma, thus increasing the spikelet fertility and ultimately the grain yield. In open-field conditions, intensified pollination and fertilization measures increased the spikelet fertility, grain weight and quality significantly under elevated temperatures. The proposed methods of enhancing pollination and fertilization are simple and effective for ameliorating the adverse effects of heat stress on the grain yield and quality in rice. This study provides strategies for sustainable rice production under the high temperatures expected with future global warming. [ABSTRACT FROM AUTHOR]