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Controlled-release urea (CRU) is widely reported to supply crop nitrogen (N) demand with one basal application, thus effectively replacing split applications of urea without diminishing grain yield and N use efficiency (NUE). However, its use for replacement for high-yield split applications of urea (CK) for rice is untested. In addition, the degree to which greenhouse gas (GHG) emissions in rice systems are affected when CRU is substituted for CK remains unclear. During 2017 and 2018, we sampled plant growth and gas emissions in a rice paddy field treated with three CRU types (sulfur-coated urea [SCU], polymer-coated urea [PCU], and bulk blended CRU [BBU]) applied via two methods (surface broadcasting on the soil and subsurface banding at 5 cm depth), with CK as a control. The three CRUs led to different soil NH4+-N dynamics, and the N supply pattern under BBU was more beneficial for rice seedling establishment than under SCU and PCU, resulting in grain yield and NUE comparable to those under CK. CRU type showed no significant effect on either CH4emissions or N2O emissions, and broadcast CRUs exhibited significantly higher total GHG emissions than CK. However, banded CRUs significantly reduced the total GHG emissions in comparison with broadcast CRUs, by 9.2% averaged across the two years. Reduced CH4emissions, particularly during the period prior to the middle drainage, contributed largely to the GHG difference. With comparably high grain yield and low total GHG emissions, banded BBU showed a low yield-scaled GHG (GHG emissions divided by grain yield) comparable to that under CK in both years. Overall, our study suggested that N management synchronized with rice demand and contributing to a high NUE tended to minimize yield-scaled GHG. Broadcast CRU can hardly substitute for CK in terms of either grain yield or GHG emissions, but banded BBU is a promising N management strategy for sustaining rice production while minimizing environmental impacts.

Global warming is expected to affect methane (CH4) emissions from rice paddies, one of the largest human-induced sources of this potent greenhouse gas. However, the large variability in warming impacts on CH4emissions makes it difficult to extrapolate the experimental results over large regions. Here, we show, through meta-analysis and multi-site warming experiments using the free air temperature increase facility, that warming stimulates CH4emissions most strongly at background air temperatures during the flooded stage of ∼26 °C, with smaller responses of CH4emissions to warming at lower and higher temperatures. This pattern can be explained by divergent warming responses of plant growth, methanogens, and methanotrophs. The effects of warming on rice biomass decreased with the background air temperature. Warming increased the abundance of methanogens more strongly at the medium air temperature site than the low and high air temperature sites. In contrast, the effects of warming on the abundance of methanotrophs were similar across the three temperature sites. We estimate that 1 °C warming will increase CH4emissions from paddies in China by 12.6%─substantially higher than the estimates obtained from leading ecosystem models. Our findings challenge model assumptions and suggest that the estimates of future paddy CH4emissions need to consider both plant and microbial responses to warming.

Elevated levels of atmospheric CO2(eCO2) promote rice growth and increase methane (CH4) emissions from rice paddies, because increased input of plant photosynthate to soil stimulates methanogenic archae. However, temporal trends in the effects of eCO2on rice growth and CH4emissions are still unclear. To investigate changes in the effects of eCO2over time, we conducted a two-season pot experiment in a walk-in growth chamber. Positive effects of eCO2on rice leaf photosynthetic rate, biomass, and grain yield were similar between growing seasons. However, the effects of eCO2on CH4emissions decreased over time. Elevated CO2increased CH4emissions by 48%–101% in the first growing season, but only by 28%–30% in the second growing season. We also identified the microbial process underlying the acclimation of CH4emissions to atmospheric CO2enrichment: eCO2stimulated the abundance of methanotrophs more strongly in soils that had been previously exposed to eCO2than in soils that had not been. These results emphasize the need for long-term eCO2experiments for accurate predictions of terrestrial feedbacks.

Poor light stress causes lodging risks in hybrid indica rice (Oryza sativaL.) in Sichuan Basin, China. However, the effective way of improving lodging resistance of hybrid indica rice by plant regulation strategy under poor light stress has not yet been investigated. A 2‐yr field study, comparing the three foliar application uniconazole rates under normal light and shading condition, was conducted to determine the lodging resistance and its physiological mechanism by using two hybrid rice varieties (Yuxiang203 [YX203] and Cliangyouhuazhan [CLYHZ]). The results showed that shading significantly decreased grain yield, but, increased lodging index (LI) due to poor stem breaking strength (M). Also, shading increased the non‐structural carbohydrates (NSC), but reduced structural carbohydrate (SC), especially for lignin in basal culm and thus, weakened the stem stiffness. Grain yield was first increased, and then declined with increasing foliar uniconazole rates. And, LI decreased sharply owing to improvement of M while reduction of bending moment by whole plant (WP). Larger section modulus (SM) of YX203 and higher bending stress (BS) of CLYHZ were contributed to higher M. Correlation analysis showed that M was significantly correlated with culm diameter, culm wall thickness and SC content for YX203, and that with SC content for CLYHZ, respectively. The results indicated that foliar application of uniconazole increased lodging resistance of hybrid indica rice for larger M and SC accumulation in basal stem. Uniconazole foliar application at 40 mg L–1can increase lodging resistance while maintaining grain yield of hybrid indica rice in the Sichuan Basin, China. Shading rapidly raised lodging risks of hybrid indica rice due to poor stem strength of basal stem.The foliar application uniconazole increased lodging resistance of hybrid indica rice.The higher stem strength of Yuxiang203 rely on section modulus and structural carbohydrates.Uniconazole rate at 40 mg L–1rose lodging resistance and yield of hybrid indica rice in the Sichuan Basin.

Belowground fertilization is a prevalent strategy for considerable grain yield and N utilization. However, the optimal fertilization depth remains uncertain in paddies, especially for slow/controlled release fertilizers. This study aimed to clarify the effect of deep “controlled‐release blended fertilizer” (CRBF) fertilization on rice (Oryza sativaL.) yield and N utilization. Two N‐fertilizer types were selected (a) urea and (b) CRBF, both combined at three fertilization depths (a) 0 cm, (b) 5 cm, and (c) 10 cm. The results showed that the grain yield was significantly affected by fertilizer type and fertilization depth. The yield achieved from CRBF was 7.8% higher than that from the urea application. Deep fertilization could also increase the rice yield with the optimum achieved from the 5‐cm depth fertilization (yield increased by 15.1% compared to that from the manual surface fertilization). Overall, the 5‐cm depth CRBF fertilization achieved the highest yield among all treatments with 12.21 and 11.84 t ha–1for 2018 and 2019, respectively. The larger sink was the main reason for this performance. Additionally, the higher photosynthetic efficient population after earing was another principal driver to the higher yield from CRBF. Due to the higher N uptake, CRBF application increased both N partial factor productivity (PFP) and recovery efficiency (RE) (P < .05); fertilization depth also had a striking effect on PFP and RE (P < .05 or .01). The 5‐cm depth fertilization of CRBF achieved the highest N utilization for both years. The results suggest that 5‐cm depth fertilization combined with controlled‐release fertilizer is a suitable strategy for higher rice yield and N utilization. The grain yield from CRBF was higher than that from the urea application treatments.Deep fertilization proved to be a strategy able to increase rice yield.The CRBF fertilization at a 5‐cm depth could achieve the optimum yield.For the yields achieved, CRBF fertilization at 5‐cm depth achieved the highest N utilization.

Temperature of a plant organ constitutes an integrative index to its eco-physiological properties and status. However, little attempt has been made to dissect the combined effect of ecological and physiological factors on the surface temperature of a plant organ such as the rice spikelet. In this study, using a deactivated plant as reference, we developed a novel comparison method to dissect the environmental and physiological effects on temperature of rice spikelet. Three japonicarice cultivars with contrasting canopy features were used as testing materials. Temperatures of flag leaf, superior and inferior spikelets and their diurnal rhythm during grain filling stage were precisely measured by a hand-held infrared thermometer. The results showed that the variation of environmental conditions within a panicle was relatively minor, posing a limited influence on temperature difference between the superior and inferior spikelet. On the other hand, it was the intrinsic physiological properties that considerably affected the spatial variations of spikelet temperature within a panicle. Chemical analysis of sucrose and starch in grains and bracts indicated that the superior spikelet is more physiologically active at photosynthetic assimilation and starch biosynthesis. Interestingly, sugar in bracts exhibited a pattern of diurnal changes similar to the source leaf but different from the sink grain, confirming that bracts are source organs for grain filling. Our findings yield penetrating insight into the eco-physiological foundation of spikelet temperature, thus being helpful for the application of physiological approaches in crop breeding for cooler canopy.

Carbon isotope composition (δ13C) of a plant organ is an inherent signature reflecting its physiological property, and thus is used as an integrative index in crop breeding. It is also a non-intrusive method for quantifying the relative contribution of different source organs to grain filling in cereals. Using the samples collected from two-year field and pot experiments with two nitrogen (N) fertilization treatments, we investigated the temporal and spatial variations of δ13C in source organs of leaf, sheath, internode, and bracts, and in sink organ grain. Constitutive nature of δ13C was uncovered, with an order of leaf (−27.84‰) < grain (−27.82‰) < sheath (−27.24‰) < bracts (−26.81‰) < internode (−25.67‰). For different positions of individual organs within the plant, δ13C of the leaf and sheath presented a diminishing trend from the top (flag leaf and its sheath) to the bottom (the last leaf in reverse order and its sheath). No obvious pattern was found for the internode. For temporal variations, δ13C of the leaf and sheath had a peak (the most negative) at 10 days after anthesis (DAA), whereas that of the bracts showed a marked increase at the time point of anthesis, implying a transformation from sink to source organ. By comparing the δ13C in its natural abundance in the water-soluble fractions of the sheath, internode, and bracts with the δ13C in mature grains, the relative contribution of these organs to grain filling was assessed. With reference to the leaf, the internode accounted for as high as 32.64% and 42.56% at 10 DAA and 20 DAA, respectively. Meanwhile, bracts presented a larger contribution than the internode, with superior bracts being higher than inferior bracts. In addition, N topdressing reduced the contribution of the internode and bracts. Our findings clearly proved the actual significance of non-foliar organs of the internode and bracts for rice yield formation, thus extending our basic knowledge of source and sink relations.

Accurate prediction of future rice yield needs the precise estimations of rice yield response to climate change factors, of which the most important one is the increasing carbon dioxide (CO2) concentrations. Estimates of CO2fertilization effect (CFE) on rice, however, still had large uncertainties. Therefore, using the rice planting areas in East China as the study area, we firstly compared the rice yields and CFE predicted by four state-of-the-art crop models, and found that the CFE predicted by these models had significant differences. We then quantified the CFE on rice yield using the field-controlled experiment conducted at Danyang site at Jiangsu province. Using CFE measurements from a field experiment as benchmark, we have developed an experiment–model integration approach aiming to reduce this variation. This study thus highlights the large CFE uncertainties of current crop models and provides us with a method to reduce this uncertainty, which is beneficial for the accurate prediction of future global rice yield in the context of climate change.

Synchronizing the nitrogen (N) supply of slow- and controlled-release N fertilizers (SCRNFs) with rice N demand is pivotal in substituting multiple urea applications by a single basal application of SCRNFs. Traditional assessment of N supply characteristics focuses mainly on N release patterns, which are only applicable to coated SCRNFs and ignore N transformation mechanisms, thus raising the need for a more universal and reliable index. Based on the ability of crop N status to detect N deficiency or excess, we hypothesized that employing leaf N balance index (NBI) as a measure of N status could provide new insights into assessing N supply characteristics of SCRNFs. We conducted field experiments involving four individual SCRNFs-humic acid urea (HAU), sulfur-coated urea (SCU), urease inhibitor urea (UIU), and polymer-coated urea (PCU)- and their four combined forms, along with the high-yield urea split application as control (CK). The results showed that NBI dynamics relative to CK could reflect the N supply potential of different SCRNFs while classifying them as short-, medium-, and long-acting fertilizers. Combinations that incorporated the long-acting SCRNF (PCU) consistently outperformed others in yield (by 5.5%) and N use efficiency (by 42.8%) by providing a more consistent and efficient N supply throughout the rice growth cycle. Grain yield showed negative correlation with the difference in NBI dynamics between SCRNFs and CK, indicating synchronizing N supply between one-time application of SCRNFs and conventional high-yield fertilization is the key for high yield. Our findings identify the potential of N status diagnosed by leaf NBI to evaluate N supply characteristics of SCRNFs and emphasize the significant role of synchronized N supply for a one-time SCRNF application.

A series of modified polysaccharide microparticles have been fabricated and their potential application for scavenging reactive oxygen species (ROS) and their derivatives to achieve osteoarthritis (OA) treatment has been explored. These microparticles were cross-linked dextran (Sephadex) with different carbazate substitution ratios determined by the TNBS assay and elemental analysis. It has been demonstrated that they could effectively scavenge carbonylated proteins and ROS including hydroxyl radicals (OH), superoxide anions (O2−) and H2O2and their derivatives with high efficiency, improve the viability of H2O2-treated chondrocytes by reducing their ROS levels, as well as lower their inflammatory factors. The above ability of antioxidation and inflammation resistance improved with the increase of carbazate substitution ratio. Significantly, this work provided the proof that modified Sephadex successfully alleviated the deterioration of cartilage and the progression of OA in vivo. The proposed microparticles showed a very promising capability for reducing ROS levels and further treating OA.

Correction for ‘Carbazate-modified cross-linked dextran microparticles suppress the progression of osteoarthritis by ROS scavenging’ by Yanfeng Ding, et al., Biomater. Sci., 2021, 9, 6236–6250. https://doi.org/10.1039/D1BM00743B.

Seedling transplanting is one of the predominant rice production systems in China. The production of hydroponically grown long‐mat rice seedlings (HLMS) is a novel seedling cultivation method that reduces labor costs and improves efficiency. There is an urgent need to explore the optimum seedling age that maximizes grain yield from HLMS. Experiments were conducted to investigate the effects of seedling age on the seedling quality, field growth characteristics and grain yield of rice grown from HLMS. The grain yield was higher for young seedlings (13 d) than for older seedlings (27 d) as a result of robust seedling quality, increased mechanical transplanting quality, slight transplanting shock, sufficient tillers and increased panicle numbers in both cultivars when grown from HLMS under normal seeding density, and there was no significant difference in grain yield between transplanted 13‐ and 20‐d‐old seedlings. Moreover, the decreased yield in Wuyunjing24 might due to the reduced number of spikelets per panicle in old seedlings. In addition, the force of root entwining was significantly enhanced with increasing seedling age for both seedling cultivation methods and cultivars, and it was significantly higher for HLMS than for conventional mat seedlings raised in soil (CMSS). In general, transplanting young seedlings (13–20 d) by the HLMS method under normal seeding density brings better plant performance and higher yield than does transplanting older seedlings; relative to CMSS, HLMS increased the flexibility of seedling age (>7 d) and operational feasibility, which can be mainly ascribed to the enhanced force of root entwining. Core IdeasHydroponically grown long‐mat seedlings significantly enhanced the force of root entwining (>8 kilograms per block), enabling rice seedlings of different ages to withstand farming operations.Relative to conventional mat seedlings raised in soil, hydroponically grown long‐mat seedlings increased the flexibility of seedling age at transplant (>7 d).Transplanting young seedlings (13–20 d) by the hydroponically grown long‐mat seedlings method achieved higher grain yield than did transplating older seedlings (27 d) under normal seeding density. Hydroponically grown long‐mat seedlings significantly enhanced the force of root entwining (>8 kilograms per block), enabling rice seedlings of different ages to withstand farming operations. Relative to conventional mat seedlings raised in soil, hydroponically grown long‐mat seedlings increased the flexibility of seedling age at transplant (>7 d). Transplanting young seedlings (13–20 d) by the hydroponically grown long‐mat seedlings method achieved higher grain yield than did transplating older seedlings (27 d) under normal seeding density.

Drug delivery via intra-articular (IA) injection has proved to be effective in osteoarthritis (OA) therapy, limited by the drug efficiency and short retention time of the drug delivery systems (DDSs). Herein, a series of modified cross-linked dextran (Sephadex, S0) was fabricated by respectively grafting with linear alkyl chains, branched alkyl chains or aromatic chain, and acted as DDSs after ibuprofen (Ibu) loading for OA therapy. This DDSs expressed sustained drug release, excellent anti-inflammatory and chondroprotective effects both in IL-1βinduced chondrocytes and OA joints. Specifically, the introduction of a longer hydrophobic chain, particularly an aromatic chain, distinctly improved the hydrophobicity of S0, increased Ibu loading efficiency, and further led to significantly improving OA therapeutic effects. Therefore, hydrophobic microspheres with greatly improved drug loading ratio and prolonged degradation rates show great potential to act as DDSs for OA therapy.

Split fertilization strategy is popularly adopted in rice to synchronize soil nitrogen (N) supply and crop N demand. Attention has been paid more on mid-season topdressing N, but limited on basal N. A clearer understanding of the basal N fate under split fertilization is crucial for determining rational basal N split ratio to improve the yield and reduce the loss to environment. A two-year field experiment with two N rates of 150 and 300 kg N ha−1, two split ratios of basal N, 40% and 25%, and two rice varieties, Wuyunjing 23 (japonica) and Y-liangyou 2 (super hybrid indica), was conducted. Labelled 15N urea was supplied in micro-plots as basal fertilizer to determine the plant uptake, translocation, soil residual, and loss of basal N fertilizer. The results showed that basal N absorbed by rice was only 1.6%–11.5% before tillering fertilization (8–10 d after transplanting), 6.5%–21.4% from tillering fertilization to panicle fertilization, and little (0.1%–4.4%) after panicle fertilization. The recovery efficiency of basal N for the entire rice growth stage was low and ranged from 18.7% to 24.8%, not significantly affected by cultivars or N treatments. Soil residual basal N accounted for 10.3%–36.4% and decreased with increasing total N rate and basal N ratio, regardless of variety and year. 43.8%–70.4% of basal N was lost into the environment based on the N balance. Basal N loss was significantly linearly positive related with the basal N rate and obviously enhanced by the increasing basal N ratio for both varieties in both 2012 and 2013. The N use efficiency and yield was significantly improved when decreasing the basal N ratio from 40% to 25%. The results indicated that the basal N ratio should be reduced, especially with limited N inputs, to improve the yield and reduce the N loss to the environment.

Basal silicon promotes rice growth and development at the tillering stage.After flooding, foliar spraying N or silicon timely had a better effect.Foliar spraying N had more advantages than silicon. Flooding is a major threat to rice (Oryza sativaL.) yields. We wondered if basal Si and foliar spraying fertilizer had an influence on rice submerged at tillering stage. The results showed that basal Si application promoted rice growth and development at the tillering stage, improving rice seedling tolerance to submergence stress. After the occurrence of flooding, timely foliar spraying of N or Si had significant remedial effects, and spraying N along with Si had a better effect. The combination of basal Si and post‐flooding N and Si spraying was the most promising method of nutrient application and as resistance to damage during submergence was enhanced, plants rapidly resumed growth and development. By maintaining a great number of green leaves and tillers as well as higher aboveground and belowground dry mass, sugar contents and antioxidant enzyme activities, these plants yielded significantly more grain. We conclude that reasonable use of Si leads to resistance and alleviation of the damaging effects of submergence and contributes to reducing yield losses in rice.

Rice culm carbohydrate transport can simultaneously affect grain filling and stem lodging resistance by regulating non-structural carbohydrate (NSC) and structural carbohydrate (SC) contents. However, the relationship between carbohydrate transposition and culm strength is not well documented. Accordingly, a high-yielding hybrid rice cultivar (Y Liangyou 2) was tested under different N fertilization regimes at two locations, Taoyuan (a special high-yield eco-site), Yunnan province and Danyang (a representative eco-site of the middle and lower Yangtze), Jiangsu province, China. Significantly higher grain yield and basal stem strength were found at Taoyuan than Danyang under all N rates throughout the two-year experiment. At heading stage, soluble sugars, starch, cellulose and lignin contents of the basal culm at Taoyuan were significantly 132.0%, 73.7%, 1.2%, and 62.7% higher than those at Danyang, respectively. At 20days after heading, soluble sugars and starch content at Taoyuan decreased significantly compared to Danyang, but lignin content remained higher. Culm carbohydrate transport to kernels at Taoyuan was significantly greater than that at Danyang, and the proportion of soluble sugars and starch was correspondingly 62.9% lower. However, the proportion of lignin and cellulose was 22.7% higher at Taoyuan than that at Danyang. Soluble sugars and starch partitioning were significantly reduced under an increased nitrogen application rate, but SC partitioning was little affected. There were significant positive correlations between basal culm bending stress and dry weight and cellulose and lignin proportions at both locations under all N rates, suggesting that the higher SC proportion at 20days after heading was primarily responsible for culm strength. These results suggest that high-yielding rice populations with greater culm strength require both moderate NSC transport and greater SC accumulation.

Global warming would deteriorate rice (Oryza sativaL.) quality, especially chalk characteristic. To better cope with the challenges from global warming, the effects of nitrogen (N) fertilizer at heading stage on rice quality under elevated temperature during grain‐filling stage were investigated. Four different growth regimes, including no warming without N fertilizer at heading stage (CK), elevated temperature without N fertilizer at heading stage (ET), elevated temperature with N fertilizer at heading stage (ET+N), no warming with N fertilizer at heading stage (CK+N), were conducted. Elevated temperature during grain filling was achieved by a free‐air temperature enhancement facility with the increase of 4°C in ET and 3.7°C in ET+N. Results showed that elevated temperature decreased rice appearance quality and cooking quality and increased rice nutritional quality and eating quality. Grain‐filling rate and amyloplast development for both superior and inferior spikelets were obviously accelerated during early grain‐filling stage by elevated temperature. The application of N fertilizer at heading stage could inhibit the deterioration of rice quality, particularly for chalk performance, and may be associated with the alleviation of grain‐filling rate and amyloplast development. The above evidence indicated that the application of N fertilizer at heading stage is efficient to mitigate rice quality deterioration under higher temperatures in the Yangtze River Valley.

Looming labor shortages and lower efficiency demand a shift from the cultivation of seedlings via the traditional nutritive soil method (CK) to hydroponically grown long‐mat seedlings (HLMS), a new method of raising rice (Oriza sativaL.) seedlings. This study was conducted to investigate the seedling quality and field growth characteristics of HLMS. We examined the effect of HLMS on seedling quality, mechanical transplantation quality, field growth characteristics, yield and benefit/cost ratio compared with those of CK (as a control). A widely grown conventional japonica rice cultivar (Wuyunjing24) and an indica hybrid rice cultivar (6Liangyou9368) were used as test material. The HLMS and CK showed no significant differences in weight/height ratio, seedling emergence rate, N content of leaves or antioxidant enzyme activities after transplantation; however, HLMS exhibited a more vigorous root system, a significantly decreased leaf area index and an extended transplantation period. The mechanical transplantation quality of HLMS was similar to that of CK but showed a significantly improved force of root entanglement. Compared with CK, the dry matter accumulation of HLMS differed quite low at the early field growth stage, whereas increased rapidly at the late growth stage. The yield and benefit/cost ratio of HLMS were equivalent or superior to those of CK. Briefly, the seedling quality of HLMS was better than that of the control, and its mechanical transplantation quality was comparable to that of the CK, enabling high‐yield and high‐efficiency rice production. Core Ideas Hydroponically grown long‐mat rice seedlings is a novel seedling cultivation method that reduces labor costs and improves efficiency.The force of root entanglement of hydroponically grown long‐mat rice seedlings was significantly improved.The yield and benefit/cost ratio of hydroponically grown long‐mat rice seedlings were equivalent or superior to those of the control. Hydroponically grown long‐mat rice seedlings is a novel seedling cultivation method that reduces labor costs and improves efficiency. The force of root entanglement of hydroponically grown long‐mat rice seedlings was significantly improved. The yield and benefit/cost ratio of hydroponically grown long‐mat rice seedlings were equivalent or superior to those of the control.

To explore the common characteristics of high‐yield rice (Oryza sativaL.) production and the influence of transplanting density on yield, field experiments were conducted in eight ecological zones with local popular high‐yield rice varieties in China in 2009. This study revealed that different ecological types of rice exhibit robust differences in growth stage, yield composition, source, sink, grain/leaf ratio, plant type traits, and dry matter (DM) accumulation and partitioning. The different ecological types of rice displayed the following common features: (i) grain yield was correlated with sink such that larger sink was always associated with larger yield; (ii) DM accumulation before and after the heading stage showed large variation in contribution to yield regardless of DM accumulation enhancement, especially for postheading accumulation, which was beneficial for increasing yield; and (iii) under the suitable seedling population (36 seedlings m−2or 25 seedlings m−2), wide rows with narrow within‐row plant spacing was conducive for building high‐yield populations. Overall, transplanting density and ecological site both have significant effects on rice yield, source‐sink relationship, and DM accumulation. Core IdeasYield was closely correlated with sink such that larger sink was always associated with higher yield.The dry matter accumulation before and after the heading stage had enormous variation in contribution to yield regardless of the dry matter accumulation enhancement, especially the yield of postheading accumulation, which was beneficial for increasing yield.Under the suitable seedling population, wide rows and narrow within‐row plant spacing was conducive for building high‐yield populations to improve the yield. Yield was closely correlated with sink such that larger sink was always associated with higher yield. The dry matter accumulation before and after the heading stage had enormous variation in contribution to yield regardless of the dry matter accumulation enhancement, especially the yield of postheading accumulation, which was beneficial for increasing yield. Under the suitable seedling population, wide rows and narrow within‐row plant spacing was conducive for building high‐yield populations to improve the yield.

Slow‐release N fertilizer is considered an effective method of improving the N use efficiency (NUE). To investigate yield and N uptake of bowl‐seedling machine‐transplanted rice (Oryza sativaL.) with slow‐release N fertilizer, three fertilizers treatments including slow‐release fertilizer blend (SFB), polymer‐coated urea (PCU), and sulfur‐coated urea (SCU), and two fertilizer methods including single basal application (B), and combined with tillering urea (BT) were performed from 2013 to 2014 in Jiangsu Yellow Sea Farm of China. Conventional split fertilization (CK) and zero N treatment (N0) are controls. Yield and NUE improvement was found in PCU under both fertilization methods in both years when compared with the CK. The SCU only showed a slight yield increase in 2014, while SFB increased the yields and NUEs under both fertilization methods in both years. The BT‐SFB got the highest yields as 13.6 and 13.3 Mg ha−1, as well as increased 7.9 and 10.8% compared with CK in both years, respectively. The recovery efficiency of N was also the highest for BT‐SFB with 52.7 and 38.5% for 2013 and 2014, respectively. The results indicated that SFB can meet the rice N demand and improve the yield and NUE, and the combined application of tillering urea and SFB was better than that of single basal application with SFB.

In rice–wheat rotation systems, crop straw is usually retained in the field at land preparation in every, or every other, season. We conducted a 3-year-6-season experiment in the middle–lower Yangtze River Valley to compare the grain qualities of rice under straw retained after single or double seasons per year. Four treatments were designed as: both wheat and rice straw retained (WR), only rice straw retained (R), only wheat straw retained (W), and no straw retained (CK). The varieties were Yangmai 16 wheat and Wuyunjing 23 japonicarice. The results showed contrasting effects of W and R on rice quality. Amylopectin content, peak viscosity, cool viscosity, and breakdown viscosity of rice grain were significantly increased in W compared to the CK, whereas gelatinization temperature, setback viscosity, and protein content significantly decreased. In addition, the effect of WR on rice grain quality was similar to that of W, although soil fertility was enhanced in WR due to straw being retained in two cycles. The differences in protein and starch contents among the treatments might result from soil nitrogen supply. These results indicate that wheat straw retained in the field is more important for high rice quality than rice straw return, and straw from both seasons is recommended for positive effects on soil fertility.

Improvement of yield in rice (Oryza sativaL.) is vital for ensuring food security in China. Both rice breeders and growers need an improved understanding of the relationship between yield and yield-related traits. New indicacultivars (53 in 2007 and 48 in 2008) were grown in Taoyuan, Yunnan province, to identify important components contributing to yield. Additionally, two standard indicarice cultivars with similar yield potentials, II You 107 (a large-panicle type) and Xieyou 107 (a heavy-panicle type), were planted in Taoyuan, Yunnan province and Nanjing, Jiangsu province, from 2006 to 2008 to evaluate the stability of yield and yield-related attributes. Growth duration (GD), leaf area index (LAI), panicles per m2(PN), and spikelets per m2(SM) were significantly and positively correlated with grain yield (GY) over all years. Sequential path analysis identified PN and panicle weight (PW) as important first-order traits that influenced grain yield. All direct effects were significant, as indicated by bootstrap analysis. Yield potential varied greatly across locations but not across years. Plant height (PH), days from heading to maturity (HM), and grain weight (GW) were stable traits that showed little variation across sites or years, whereas GD (mainly the pre-heading period, PHP) and PN varied significantly across locations. To achieve a yield of 15tha−1, a cultivar should have a PH of 110–125cm, a long GD with HM of approximately 40days, a PN of 300–400m−2, and a GW of 29–31mg.

The present study was conducted to determine whether and how store-operated Ca2+entry (SOCE) in glomerular mesangial cells (MCs) was altered by high glucose (HG) and diabetes. Human MCs were treated with either normal glucose or HG for different time periods. Cyclopiazonic acid-induced SOCE was significantly greater in the MCs with 7-day HG treatment and the response was completely abolished by GSK-7975A, a selective inhibitor of store-operated Ca2+channels. Similarly, the inositol 1,4,5-trisphosphate-induced store-operated Ca2+currents were significantly enhanced in the MCs treated with HG for 7 days, and the enhanced response was abolished by both GSK-7975A and La3+. In contrast, receptor-operated Ca2+entry in MCs was significantly reduced by HG treatment. Western blotting showed that HG increased the expression levels of STIM1 and Orai1 in cultured MCs. A significant HG effect occurred at a concentration as low as 10 mM, but required a minimum of 7 days. The HG effect in cultured MCs was recapitulated in renal glomeruli/cortex of both type I and II diabetic rats. Furthermore, quantitative real-time RT-PCR revealed that a 6-day HG treatment significantly increased the mRNA expression level of STIM1. However, the expressions of STIM2 and Orai1 transcripts were not affected by HG. Taken together, these results suggest that HG/diabetes enhanced SOCE in MCs by increasing STIM1/Orai1 protein expressions. HG upregulates STIM1 by promoting its transcription but increases Orai1 protein through a posttranscriptional mechanism.

Abstract:White-belly and white-core are the major two types of grain chalkiness in japonica rice. This study aims to compare the morphological features of white-belly and white-core using a scanning electron microcope (SEM). A japonica rice cultivar Wuyujing3 and its mutants were used as materials. Nearly 1000 SEM images were observed, and 12 representative photos were selected. SEM images showed contrasting differences between white-belly and white-core in endosperm microstructure including the shape of endosperm cell, the size distribution of starch granules, and the amount of protein bodies. White-belly and white-core also varied markedly in morphological features of the cracked compound starch granules. Our findings should help to advance our understanding of the multi-faceted nature of grain chalkiness from the perspective of starch and protein accumulation, and should be of value for future work on rice grain chalkiness.

Plant phenomics (PP) has been recognized as a bottleneck in studying the interactions of genomics and environment on plants, limiting the progress of smart breeding and precise cultivation. High-throughput plant phenotyping is challenging due to the spatial-temporal dynamics of traits. Proximal and remote sensing (PRS) techniques are increasingly used for plant phenotyping due to their advantages in multi-dimensional data acquisition and analysis. Over the last two decades, substantial progress of PRS applications in PP has been observed and analyzed from an interdisciplinary perspective based on 2972 publications in this study. This progress covers most aspects of PRS application in PP, including the global spatial distribution and temporal dynamic pattern, specific PRS technology, phenotypic research fields, working environments, species, and traits. Subsequently, we demonstrate how to link PRS to multi-omics studies, including how to achieve multi-dimensional PRS data acquisition and processing; how to systematically integrate all kinds of phenotypic information and derive phenotypic knowledge with biological significance; and how to link PP to multi-omics association analysis. Finally, we identify three perspectives in PRS-based PP: (i) strengthening the spatial and temporal consistency of PRS data, (ii) exploring novel phenotypic traits, and (iii) facilitating multi-omics communication.

Nitrogen (N) fertilization increases rice yield, but inappropriate N fertilizer application increases N loss and the risk of environmental pollution. Short-term fertilizer postponing (FP) generally reduces N apparent surplus and increases rice yields, but the effects of long-term FP on N surplus and rice yields remain unknown. Our study was the first to investigate the impacts of long-term FP (11 years) on N apparent surplus and rice yields. FP effects in the short term (≤6 years) did not affect rice yields, whereas FP effects in the long term (>6 years) increased rice yields by 13.9% compared with conventional fertilization (CF). FP did not affect panicles per unit area, 1000-kernel weight, and filled-kernel rate, but spikelets per panicle increased over time due to spikelet formation stimulation. FP also reduced the N apparent surplus over time more strongly than CF owing to higher N accumulation and N utilization efficiency. FP effects in the long term also significantly increased soil organic matter, total N, and NH4+-N content. Our results were supported by a pot experiment, showing that rice yields in soils with a history of FP were significantly higher than those for soils without a history of FP, indicating that FP increased rice yields more strongly in later years mainly because of soil quality improvement. Our findings suggest that long-term FP can reduce N loss while increasing rice yields by improving soil quality.

Auxin and cytokinin (CTK) play important roles in the regulation of rice (Oryza sativaL.) tiller bud growth. Auxin inhibits bud growth and CTK promotes growth; however, little is known about the positional effects of these hormones in the regulation of rice tiller bud growth. In the present study, indole‐3‐acetic acid (IAA) and 6‐benzylaminopurine (6‐BA) (a synthetic CTK) were applied to different leaves and roots at the tillering and heading stages of rice development, and the growth of rice tiller buds on the unelongated and elongated internodes was measured. Additionally, hormonal variations of the plants were examined and recorded. The objectives of the present study were to investigate the positional effects of auxin and CTK on the regulation of rice tiller bud growth. The results indicate that IAA has a notable positional effect on the regulation of rice tiller bud growth, and the positional effect of IAA was closely related to its polar transport. An increase in leaf IAA levels inhibited the growth of tiller buds located at unelongated nodes; however, growth of tiller buds at elongated nodes was inhibited only when IAA levels were increased in the upper‐stem leaves or the leaves at which the tiller bud was located. Contrary to IAA, 6‐BA had no positional effect on rice tiller bud growth. Application of 6‐BA to different leaves and roots significantly promoted the growth of rice tiller buds at both unelongated and elongated nodes.

In the present study, 40 mg L−1N (NH treatment) and 20 mg L−16‐benzylaminopurine (6‐BA; BA treatment) were used to stimulate tiller bud growth in rice (Oryza sativaL.). The hormone changes in the tiller nodes and tiller buds and the N levels in the leaf blades, leaf sheaths, and tiller nodes were measured. The results indicate that N and 6‐BA promoted tiller bud germination and increased the indole‐3‐acetic acid (IAA) and zeatin (Z) plus zeatin riboside (ZR) levels in tiller buds and tiller nodes but decreased the abscisic acid (ABA) levels in tiller buds. Before tiller bud germination, the IAA and Z plus ZR levels increased but the ABA did not change, suggesting that IAA and Z plus ZR but not ABA may be the key regulators of tiller bud growth. From 4 d posttreatment, the tiller bud growth of the BA‐treated plants markedly slowed but the buds of the NH‐treated plants continued to grow quickly. We also found that the N levels in the leaf blades, leaf sheaths, and tiller nodes of the NH‐treated plants increased significantly as compared to those of the control plants (the plants treated with 10 mg L−1N). However, no significant differences in N levels were observed between the plants of BA and control treatments. This study suggests that N may regulate tiller bud growth in two ways: by regulating N metabolism and regulating endogenous hormones. External 6‐BA promoted tiller bud germination by regulating endogenous hormones, but tiller bud growth was not maintained because it could not increase the N levels in the plants.

Abstract: Diabetes mellitus is complicated with the development of cardiac contractile dysfunction and electrical instability, which contributes to high morbidity and mortality in diabetic patients. This study examined the possible roles of enhanced endothelin-1 (ET-1) on diabetes-induced alterations in ventricular myocyte electrophysiology. Type 1 diabetic rats were induced by single dose injection of streptozotocin (STZ) and treated with or without ET-1 receptor antagonist bosentan for 8 wk before myocyte isolation. Action potential, outward K+ currents, and inward Ca2+ currents in ventricular myocytes were recorded using whole-cell patch clamp technique. STZ-injected rats exhibited hyperglycemia, reduced body weight gain, and elevated plasma ET-1 concentration, indicative of diabetes induction. Ventricular myocytes isolated from diabetic rats exhibited prolonged action potential and reduced all three types of outward K+ currents. Resting membrane potential, height of action potential, and L-type Ca2+ current were not altered in diabetic myocytes. In vivo chronic treatment of diabetic rats with bosentan significantly augmented K+ currents and reversed action potential prolongation in ventricular myocytes. On the other hand, bosentan treatment had no detectable effect on the electrophysiological properties in control myocytes. In addition, bosentan had no effect on L-type Ca2+ currents in both control and diabetic myocytes. Our data suggest that altered electrophysiological properties in ventricular myocytes were largely resulted from augmented ET-1 system in diabetic animals.

Abstract: The main characteristics of type 1 diabetic cardiomyopathy include depressed contractility and altered electrophysiological properties in ventricular myocytes. The goal of the present study was to determine the potential influence of gender in the diabetes-induced pathogenesis of ventricular myocyte function. Diabetes in both male and female rats was induced by a single intravenous injection of streptozotocin (STZ). Diabetic rats exhibited hyperglycemia and reduced body weight gain in both male and female groups. Neither contractile profiles nor activity of three types of K+ channels of ventricular myocytes was significantly different between nondiabetic male and female rats. Ventricular myocytes isolated from diabetic rats exhibited significant depresion in cell contraction and relaxation, which was associated with depression of intracellular Ca2+ ([Ca2+]i) transient. The degrees of contractile depression were comparable in ventricular myocytes obtained from both male and female diabetic rats. Similarly, diabetes depressed three types of outward K+ currents (Ito, Ik, and iss) to the same extent in both gender myocytes. These data demonstrate that in this animal model of diabetes, gender difference in cardiac myocyte functions was eliminated.

AbstractProteins and carbohydrates in developing rice panicles were analyzed to see whether these parameters control spikelet number in rice. Two rice cultivars and 2 levels of nitrogen topdressing were used to obtain panicles with different numbers of spikelets. A japonica rice cultivar, Nipponbare, with topdressing (H) had 1.8 times more spikelets per panicle than that without topdressing (L). Moreover, the number of spikelets per panicle in an indica rice cultivar, Takanari, without topdressing was 2.7 times larger than that in Nipponbare-L. Panicles with more spikelets (LP) in Nipponbare-H and Takanari-L showed slower growth than those with few spikelets (SP) in Nippanbare-L in an early stage. LP, however, increased markedly in size thereafter, eventually exceeding SP, in length and fresh weight. Soluble protein content was higher in LP than SP in an early stage, but this difference was hardly detected in a late stage. No clear difference was observed in sugars or starch between LP and SP. Analysis of soluble and insoluble proteins by SDS-polyacrylamide gel electrophoresis showed that bands corresponding to insoluble proteins with a molecular weight about 42 kDa were present at higher intensities in LP than in SP. These results suggest that the spikelet number in rice is controlled by the soluble protein content in an early stage and insoluble proteins with a molecular weight of 42 kDa during panicle development, but not by the carbohydrates in developing panicles.

Straw incorporation is a global common practice to improve soil fertility and rice yield. However, the effect of straw incorporation on rice yield stability is still unknown, especially under high fertilization level conditions. Here, we reported the effect of straw returning on rice yield and yield stability under high fertilization levels in the rice–wheat system over nine years. The results showed that straw incorporation did not significantly affect the average rice yield of nine years. Straw incorporation reduced the coefficient of variation of rice yield by 25.8% and increased the sustainable yield index by 8.2%. The rice yield positively correlated with mean photosynthetically active radiation (PAR) of rice growth season and the effects of straw incorporation on rice yield depended on the PAR. Straw incorporation increased the rice yield by 5.4% in the low PAR years, whereas it did not affect the rice yield in the high PAR years. Long-term straw incorporation lowered soil bulk density but improved the soil organic matter, total N, available N, available P, and available K more strongly than straw removal. Our findings suggest that straw incorporation can increase rice yield stability through improving the resistance of rice plant growth to low PAR.

Interaction between the embryo and endosperm affects seed development, an essential process in yield formation in crops such as rice. Signals that mediate communication between embryo and endosperm are largely unknown. We used the notched-belly (NB) mutant with impaired communication between embryo and endosperm to investigate the effect of the embryo on developmental staging of the endosperm and signaling pathways in the embryo that regulate endosperm development. Hierachical clustering of mRNA datasets from embryo and endosperm samples collected during development in NB and a wild type showed a delaying effect of the embryo on the developmental transition of the endosperm by extension of the middle stage. K-means clustering further identified coexpression modules of gene sets specific to embryo and endosperm development. Combined gene expression and biochemical analysis showed that T6P–SnRK1, gibberellin and auxin signaling by the embryo regulate endosperm developmental transition. We propose a new seed developmental staging system for rice and identify the most detailed signature of rice grain formation to date. These will direct genetic strategies for rice yield improvement.