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New indica and japonica hybrid rice cultivars, such as the Yongyou series, provide farmers with very high yield potential. However, information on their canopy light capture and solar radiation use efficiency in the late season is limited. Field experiments were performed to compare the radiation-use parameters of four rice types: indica rice (IR), inbred japonica rice (IJR), hybrid japonica rice (HJR), and hybrid indica/japonica rice (HIJR), from 2016 to 2018 during the late season in Hangzhou, China. The grain yield, aboveground biomass, intercepted solar radiation (SI), and radiation-use efficiency (RUE) of the HIJR were on average respectively 13.4%–53.4%, 14.3%–30.6%, 7.6%–21.4%, and 8.2%–14.9% higher than those of the HJR, IJR, and IR. The leaf area index (LAI) of the HIJR was 18.2%–57.0% greater than that of the IJR and HJR at four growth stages, resulting in respectively 17.8%–38.5% and 10.7%–42.8% greater canopy light interception rates (LIR) and amount of intercepted solar radiation during the vegetative stage. The prolonged grain-filling stage also led to respectively 33.9%–52.6% and 30.5%–51.4% increases in amounts of incident and intercepted radiation for the HIJR relative to the IR during grain filling. These results indicate that the SI superiority of the HIJR was caused by canopy closure as rapid as that of the IR during the vegetative stage (greater LAI and canopy LIR during the growing season) and a grain-filling stage as long as that of the HJR. For grain-filling stage, differences in leaf Pn between HIJR, IR, and IJR were not significant, suggesting that the greater RUE of the HIJR (12.7%–52.8% higher) than that of the other rice types resulted from improved canopy architecture after flowering (FL). Principal components analysis (PCA) revealed that the superiority of the HIJR in terms of solar radiation use resulted from the greater canopy light capture capability of IR and the prolonged growth period (especially during grain filling) of japonica rice in the late growing season.

Environmental conditions greatly affect the growth of rice. To investigate the geographic differences in yield formation of single-season high-yielding hybrid rice in southern China, experiments were conducted in 2017 and 2018 in the upper and middle–ower reaches of the Yangtze River with 10–30 main locally planted high-yielding hybrid cultivars used as materials. Compared with rice planted in the middle–lower reaches of the Yangtze River, rice planted in the upper reaches has a longer tillering duration, higher accumulated temperature (≥10°C) during tillering period, but lower accumulated temperature and solar radiation from initial booting to maturity. Yield traits comparison between the upper and the middle–lower reaches of Yangtze River showed that the former had 48.1% more panicles per unit area while the latter had 46.4% more grains per panicle; the rice yield in the former was positively correlated with the seed setting rate and the dry matter accumulation before heading, while the latter was positively correlated with grains per panicle and dry matter accumulation from booting to maturity. Comparison of the same variety Tianyouhuazhan planted in different regions showed there was a significant positive correlation between panicle number and the duration of and accumulated temperature during the tillering period (r=0.982**, r=0.993**, respectively), and between grains per panicle and accumulated solar radiation during booting period (r=0.952*). In the upper reaches of the Yangtze River, more than 90% of cultivars with an yield of greater than 11 t ha–1 had an effective panicle number of 250–340 m–2, and there was a significant negative correlation between seed setting rate and grains per panicle; therefore, the high-yielding rice production in these regions with a long effective tillering period (>40 d) should choose varieties with moderate grains per panicle, adopt crop managements such as good fertilizer and water measures during vegetative growth period to ensure a certain number of effective panicles, and to increase the dry matter accumulation before heading. While in regions with a short effective tillering period (

The intensive use of chemical fertilizer, particularly nitrogen (N) has resulted in not only markedly increased crop yields but also detrimental effects on ecosystems. Plant microbiomes represent an eco-friendly alternative for plant nutrition and productivity, and the effect of N fertilization on plant and soil microbes has been well studied. However, if and how N fertilization modulates seed endophytic microbiomes and grain quality remains largely unknown. Here, we investigated the effect of different N fertilization rates on rice seed endophytic bacterial and fungal communities as well as on grain quality. Higher bacterial and fungal community diversity and richness, but lower grain protein and amino acid contents were found in seeds of rice treated moderate N fertilization than those treated insufficient or excessive N input. There were also more complex co-occurrence networks, and an enrichment of putative beneficial bacterial taxa in seeds under moderate N application, while there was an opposite trend under the excessive N treatment. In addition, the grain amylose and amylopectin contents were positively correlated with the relative abundance of bacterial and fungal dominant genera, while the grain amino acid contents were negatively correlated with the bacterial dominant genera but positively associated with fungal dominant genera. Together, we demonstrate that moderate N fertilization can enhance bacterial and fungal community colonization in seeds and improve grain eating and cooking qualities. This study extends our knowledge regarding the significant role of rational fertilization on seed-microbe interactions in sustainable agriculture.

Observations of the effects of long-term paddy-upland rotations on soil carbon (C) and nitrogen (N) stocks are scarce. This experiment used four paddy-upland rotation systems with summer rice as the main crop: rice-winter fallow (RF), rice-potato with rice straw mulch and return (RP), rice-wheat (RW), and rice-Chinese milk vetch (RC) with the return of winter crop residues (from 2003 to the present) to examine the soil C and N stock characteristics in the 0–50 cm soil layer. The results showed that in the topsoil at 50 cm, compared to RF, both RP and RC increased the soil organic carbon (SOC) stock by 19.67% and 15.29%, the total nitrogen (TN) stock by 20.40% and 18.54%, and the available nitrogen (AN) density by 61.54% and 34.44%, respectively; in particular, the increases in the TN and AN at 20–30 cm were likely to increase the rice yield. RW increased only the AN density by 30.24% compared with RF. Furthermore, the highest SOC, TN, and AN densities were all observed in RP. Except for TN at 30–40 cm, the densities of SOC, TN, and AN in RP were slightly greater than those in the other treatments due to the high C and N concentrations at 0–40 cm; thus rice-potato with rice straw mulch was the best choice for increasing soil C and N accumulation and improving rice yield. In addition, SOC, TN, and AN had obvious stratification and surface aggregation characteristics at 0–50 cm, and 72.17%–83.37% of the total SOC stock, 75.70%–80.48% of the total TN stock and 75.69%–81.08% of the total AN density were concentrated in the top 30 cm. However, the characteristics were dependent on the residues.

This study aimed to investigate whether an interaction existed between ethylene and polyamines (PAs), which mediated the effects of water stress (WS) during meiosis on rice (Oryza sativa L.) spikelet degeneration. Two indica hybrid rice cultivars, HY113 (a drought-resistant rice cultivar) and ZZY8 (a drought-susceptible rice cultivar), were used in the present study, which were exposed to two soil moisture treatments: well water (WW) and WS. The spikelet degeneration rate (SDR) in WS plants increased by 12.1% for HY113 and 29.5% for ZZY8 compared with WW plants. The concentration of free spermidine (Spd) and free spermine (Spm) and the activities of S-adenosyl-l-methionine decarboxylase and Spd synthase were all significantly reduced in young panicles by the WS, with more reduction for ZZY8 than for HY113. The ethylene evolution rate, the concentrations of putrescine (Put), 1-aminocylopropane-1-car-boxylic acid (ACC), and H2O2, and the activities of ACC synthase and ACC oxidase in young panicles significantly increased for both cultivars under WS treatment, with more increase for ZZY8 than for HY113. Furthermore, when Spd or aminoethoxyvinylglycine (an inhibitor of ethylene synthesis) was applied to the young panicles of WS plants in the pollen mother cell meiosis prophase, the SDR significantly reduced. An opposite effect was observed when ACC or methylglyoxal-bis(guanylhydrazone) (an inhibitor of Spd and Spm synthesis) was applied to young panicles of WS plants. The results of the present study suggested the existence of an antagonistic interaction between ethylene and PA biosynthesis, which likely mediated the effect of WS during meiosis on rice spikelet degeneration.

Hybrid japonica cultivars, such as the Yongyou series, have shown high yield potential in the field in both the early and late growing seasons. Moreover, understanding the responses of rice flowering dates to temperature and light is critical for improving yield performance. However, few studies have analyzed flowering genes in high-yielding japonica cultivars. Based on the five sowing date experiments from 2019 to 2020, select the sensitive cultivar Yongyou 538 and the insensitive cultivar Ninggeng 4 and take their flag leaves and panicles for transcriptome analysis. The results showed that compared with sowing date 1 (6/16), after the sowing date was postponed (sowing date 5, 7/9), 4480 and 890 differentially expressed genes (DEGs) were detected in the leaves and panicles in Ninggeng 4, 9275 and 2475 DEGs were detected in the leaves and panicles in Yongyou 538, respectively. KEGG pathway analysis showed that both Ninggeng 4 and Yongyou 538 regulated rice flowering through the plant circadian rhythm and plant hormone signal transduction pathways. Gene expression analysis showed that Os01g0566050 (OsELF3-2), Os01g0182600 (OsGI), Os11g0547000 (OsFKF1), Os06g0275000 (Hd1), and Os09g0513500 (FT-1) were expressed higher and Os02g0771100 (COP1-1) was expressed lower in Yongyou 538 compared with Ninggeng 4 as the climate conditions changed, which may be the key genes that regulate the flowering process with the change of temperature and light resources in sensitive cultivar Yongyou 538 in the late season.

Crop rotation has been used worldwide for thousands of years. It is well documented that the crop rotation system benefits soil improvement and crop yields. Based on this complexity, the me...

The conjugate-linear anti-involutions and unitary irreducible modules of the intermediate series over the twisted Heisenberg–Virasoro algebra are classified, respectively. We prove that any unitary irreducible module of the intermediate series over the twisted Heisenberg–Virasoro algebra is of the form [Formula: see text] for [Formula: see text], [Formula: see text] and [Formula: see text].

There are no simple singular Whittaker modules over most of important algebras, such as simple complex finite-dimensional Lie algebras, affine Kac–Moody Lie algebras, the Virasoro algebra, the Heisenberg–Virasoro algebra and the Schrodinger–Witt algebra. In this paper, however, we construct simple singular Whittaker modules over the Schrodinger algebra. Moreover, simple singular Whittaker modules over the Schrodinger algebra are classified. As a result, simple modules for the Schrodinger algebra which are locally finite over the positive part are completely classified. We also give characterizations of simple highest weight modules and simple singular Whittaker modules.

It is known that the Schrodinger-Virasoro algebras, including the original Schrodinger-Virasoro algebra and the twisted Schrodinger-Virasoro algebra, are playing important roles in mathematics and statistical physics. In this paper, we study the tensor products of weight modules over the Schrodinger-Virasoro algebras. The irreducibility criterion for the tensor products of highest weight modules with intermediate series modules over the Schrodinger-Virasoro algebra is obtained.

Straw return affects the soil N supply; however, the mechanisms underlying the effects of different straw types and substance additions on soil N availability remain elusive. This study compared net N mineralization (NNM) in soils with various straw management histories under rotations rice-fallow (RF), rice-wheat (RW) and rice-potato with straw mulch (RP) during 2003–2017. The soils were then subjected to four substrate additions, including the no-substrate control, +N [(NH4)2SO4, 0.2 mg N kg−1 dry soil], +G (glucose, 0.6 mg C kg−1 dry soil) and +G+N (both). The responses of the soil NNM to substrate additions varied depending on the soils’ different straw histories. The direction of NNM was affected by substrate addition, but the magnitude depended on crop rotation and straw management. The NNM in the +G treatment ranged from 15.5 to 71.5 mg kg−1 in the soils with various straw histories, with RW and RP having 299% and 366% greater NNM than RF, respectively. Conversely, the addition of +N and +G+N decreased the soil NNM significantly in the soil with RW and RP straw histories, being 70~75% and 28~39% lower in the +N and +G+N treatments, respectively, than in the soil without straw history (RF). In addition, long-term straw return (RP and RW) significantly increased the soil ammonium N, amino acid N, and microbial biomass C and extracellular enzyme activity, while the addition of N and C substrates altered the decomposition of soil organic N. The long-term straw history also affected the soil bacterial community and formed a significant grouping compared to RF. In general, the soil from RF was dominated by heterotrophic bacteria such as Actinobacteria, Bacteroidetes and Proteobacteria, while the soils of RP and RW were mainly Firmicutes involved in straw glycolysis and part of Proteobacteria involved in N metabolism. Adding inorganic N altered bacteria in Proteobacteria, and the relative abundance of Proteobacteria had a negative relationship with the concentration of available N, indicating that bacteria induced by exogenous N were not involved in inherent N mineralization in soil. The addition of glucose enhanced the bacterial communities involved in N mineralization. The results imply that the soil N supply capability was enhanced with straw history under N deficiency and that an excess supply of N fertilizers was immobilized to minimize leaching losses.

Increasing amounts of N fertilizer at panicle initiation or heading, and decreasing amounts at earlier stages, is recommended and commonly practiced in parts of China. The practice is based on the higher recovery efficiency (RE) of fertilizer N from later application than at earlier stages. However, this approach does not consider the amount of fertilizer N remaining in the soil (‘residual soil N’) from each application time, and the fact that a considerable amount of the N uptake by the plants, even in heavily-fertilized crops, comes from the soil N. Therefore, the uptake, residual soil N, loss and recovery efficiency of fertilizer N applied to transplanted rice at different growth stages was investigated in a field experiment conducted in 2013 and 2017. Nitrogen was applied as urea at 210 N kg ha−1 in three equal splits at transplanting (basal), tillering and panicle initiation (PI), and 15N-labeled urea was used to trace the change of fertilizer N concentration in the floodwater and soil and the recovery of fertilizer-N in the plants and soil. The fertilizer N recovery efficiency (RE) in the plants was 21–36%, and 15% of the applied 15N remained within the 0–20 cm soil depth at maturity. The RE of N applied at PI (panicle-RE) (33–58%) was greater than the RE of N applied at transplanting (basal-RE) (20–36%) and at tillering (tiller-RE) (13–29%). However, the residual soil N derived from basal fertilizer accounted for more than 90% of the total fertilizer N remaining in the paddy soil at the time of harvest. At harvest time, 70% of the basal-15N, 29% of the tillering-15N and 46% of the panicle-15N, was recovered in the plants and soil, demonstrating that the low basal-RE in the plants does not indicate high basal fertilizer-N loss. Basal-15N still accounted for more than 1% of the total soil N after heading, and all the fertilizer-15N uptake in plants after heading was derived from basal-N.

To evaluate the effects of various rotation systems on rice grain yield and N use efficiency, a paddy–upland cropping experiment (2013–2016) was conducted in southeastern China. The experiment was designed using six different rice––winter crop rotations: rice–fallow (RF), rice–wheat (RW), rice–potato with rice straw mulch (RP), rice–green manure (Chinese milk vetch; RC–G), rice–oilseed rape (RO), and rice–green manure crop (oilseed rape with fresh straw incorporated into soil at flowering; RO–G) and three N rates, N0 (0 kg N ha−1), N1 (142.5 kg N ha−1), and N2 (202.5 kg N ha−1). Average rice yields in the RF (5.93 t ha−1) rotation were significantly lower than those in the rotations with winter crops (7.20–7.48 t ha−1) under the N0 treatment, suggesting that incorporation of straw might be more effective for increasing soil N than winter fallow. The rice yield differences among the rotations varied by year with the N input. In general, the grain yields in the RP and RO–G rotations –were respectively 11.6–28.5% and 14.80–37.19% higher than those in the RF in plots with N applied. Increasing the N rate may have tended to minimize the average yield gap between the RF and the other rotations; the yield gaps were 18.55%, 4.14%, and 0.23% in N0, N1, and N2, respectively. However, the N recovery efficiency in the RF was significantly lower than that in other rotations, except for 2015 under both N1 and N2 rates, a finding that implies a large amount of chemical N loss. No significant differences in nitrogen agronomic efficiency (NAE) and physiological efficiency (NPE) were found between the rotations with legume (RC–G) and non–legume (RO and RW) winter crops, a result that may be due partly to straw incorporation. For this reason, we concluded that the return of straw could reduce differences in N use efficiency between rotations with and without legume crops. The degree of synchrony between the crop N demand and the N supply was evaluated by comparison of nitrogen balance degree (NBD) values. The NBD values in the RP and RW were significantly lower than those in the other rotations under both N1 and N2 rates. Thus, in view of the higher grain yield in the RP compared to the RW under the N1 rate, the RP rotation might be a promising practice with comparable grain yield and greater N use efficiency under reduced N input relative to the other rotations. The primary yield components of the RF and RP were identified as number of panicles m−2 and numbers of kernels panicle−1, respectively. The NAE and NPE were positively correlated with harvest index, possibly providing a useful indicator for evaluating N use efficiency. Keywords: Rice (Oryza sativa L.), Paddy–upland rotation, Nitrogen use efficiency, Winter crops

Compared to drought-susceptible rice cultivars (DSRs), drought-resistance rice cultivars (DRRs) could drastically reduce the amount of irrigation water input and simultaneously result in higher grain yield under water-saving irrigation conditions. However, the mechanisms underlying these properties are unclear. We investigated how improved agronomic traits contribute to higher yield and higher water use efficiency (WUE) in DRRs than in DSRs under alternate wetting and drying (AWD). Two DRRs and two DSRs were field-grown in 2015 and 2016 using two different irrigation regimes: continuous flooding (CF) and AWD. Under CF, no statistical differences in grain yield and WUE were observed between DRRs and DSRs. Irrigation water under the AWD regime was 275–349 mm, an amount 49.8%–56.2% of that (552–620 mm) applied under the CF regime. Compared to CF, AWD significantly decreased grain yield in both DRRs and DSRs, with a more significant reduction in DSRs, and WUE was increased in DRRs, but not in DSRs, by 9.9%–23.0% under AWD. Under AWD, DRRs showed a 20.2%–26.2% increase in grain yield and an 18.6%–24.5% increase in WUE compared to DSRs. Compared to DSRs, DRRs showed less redundant vegetative growth, greater sink capacity, higher grain filling efficiency, larger root biomass, and deeper root distribution under AWD. We conclude that these improved agronomic traits exert positive influences on WUE in DRRs under AWD. Keywords: Agronomic traits, Alternate wetting and drying, Drought-resistance rice cultivars, Grain yield, Water use efficiency

Nitrogen (N) fertilizer split-application is the most widely adopted N management in rice production. To investigate the genotypic differences in the uptake of fertilizer-N applied at different growth stages and in the partitioning of accumulated N in transplanted rice, a two-year field experiment using a split–split plot design with two N rates (105 and 210 kg ha) and three N-labelled fertilizer application treatments was conducted in three rice varieties with different fertilizer-N recovery efficiencies (FNREs). The FNRE of total fertilizer was measured, and the FNREs of basal, tillering and panicle fertilizations were analyzed by applying N-labelled urea as basal, tillering or panicle fertilizer. Although the panicle-FNRE (32%-68%) was greater than the FNREs of both basal and tillering fertilizers (10%–36% and 13%–42%, respectively), the FNRE of total fertilizer was significantly and positively correlated with both basal and tillering-FNREs (p < 0.01). The high-FNRE varieties absorbed more basal fertilizer-N compared with the low-FNRE variety and had significantly greater basal-FNRE and percentages of basal fertilizer-N in the stems at heading and in the panicles at maturity. Early and quick tillering emergence was observed in the high-FNRE varieties, and there was a significant positive relationship between basal-FNRE and tillering rate. The above results indicate that the difference in basal fertilizer-N absorption plays an important role in the genotypic difference in FNRE, and high-FNRE varieties might be selected from the varieties characterized by fast tillering in the early growth stages.

Salicylic acid (SA) can alleviate damage to rice plants induced by heat stress, but its role in preventing spikelet degeneration under high-temperature stress has not been documented. Rice plants pretreated with SA (0–50 mmol L−1) were subjected to heat stress at 40 °C at the pollen mother cell meiosis stage for 10 days. The results indicated that there were no significant differences in grain yields and yield components among rice plants that were exogenously sprayed with SA (0–50 mmol L−1) under natural conditions. Under heat stress, the grain yield, spikelet number per panicle and setting rate in response to SA treatments were higher than under the control (0 mmol L−1 SA or NON-SA) treatment, especially with 1 and 10 mmol L−1 SA. A higher grain yield, spikelet number per panicle and setting rate were recorded in these two SA treatments compared with the NON-SA treatment. During this process, soluble sugars, proline, phytohormones including ABA, GA3, BRs, IAA, ZR and JA, and antioxidant enzymes, such as superoxide dismutase, peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), were induced by SA. Moreover, soluble sugars, IAA, POD and APX in the spikelets with SA treatments were not only higher than with the NON-SA treatment but the changing patterns were also similar to that of the spikelet number per panicle under natural conditions and heat stress. Therefore, our results suggest that sugars, antioxidant enzymes and IAA might mediate SA to prevent spikelet degeneration caused by heat stress.

The seedling establishment phase is important for the productivity and profitability of rice ( Oryza sativa L.) production. To evaluate the role of climatic and physiological factors in different growth seasons in determining the rice grain yield, field experiments were conducted with four seedling establishment methods: manual transplanting (TP), seedling throwing (ST), machine transplanting (MT), and direct seeding (DS). Three nitrogen application rates were also tested (zero, medium, and high N rate) under single, early, and late seasons in the Middle and Lower reaches of the Yangtze River in 2013 and 2014. The results showed that the average grain yields of MT, ST and TP did not differ significantly under the N rate of 127.5–142.5 kg N/ha. Under the high N rate (187.5–202.5 kg/ha), the average grain yields in TP were 6.5%, 10.6%, and 36.7% greater than those in MT, ST, and DS, respectively, suggesting that TP rice had greater yield potential than the others, irrespective of rice seasons. In the single season condition, the grain yield advantage of TP over MT and SC might be attributable to the higher panicle-bearing tiller rate and greater sink size in TP with high N rates. It is less clear why the yield was not significantly higher in the double season. On the other hand, the average grain yields were −3.5%–8.8%, 6.4%–15.0%, and 29.4%–37.1% lower under DS than under the other treatments in the single, early, and late seasons, respectively, suggesting that DS might be a promising choice with less input and stable yield output in the single season. The dramatic yield loss in DS in the late season might be attributed to the reduced grain setting rate (a 20.3%–33.3% decrease under DS compared with the other treatments in the late season), indicating that the current varieties used for TP in the late season were not suitable for DS cultivation. The correlation between the grain yield and climate factors suggests that the light and temperature accumulation in the double season might be a barrier to narrowing the yield gaps between DS and TP rice in early and late rice, but was not the yield-limiting factor in the single season.

Retaining crop residue is an important agronomic practice in sustainable agriculture, particularly to maintain soil organic carbon (SOC). To evaluate the effect of the retention of different types of crop residues on SOC and labile fractions, a long-term rice-based crop rotation experiment was established with five different winter cropping practices: (1) rice-fallow (RF), (2) rice–wheat (RW), (3) rice–potato with rice straw mulch (RP), (4) rice–green manure (Chinese milk vetch; RG), and (5) rice–oilseed rape (RO). The results showed that the annual rice yields in the RP, RO, RG, and RW treatments were not significantly different from each other, but 13.3%, 10.2%, 10.3%, and 8.4% higher, respectively, than in the RF treatment. Furthermore, the soil properties in the RP system improved significantly compared with those at the initiation of the study, with increases of 14.7% in total N, 17.5% in total P, 77.2% in available K, and 13.9% in SOC content. Considering the slight rice yield increase and superiority in the annual net income, the RP treatment seems to be a promising rotation system to meet the sustainability requirements for the agro-ecosystem. The responses of the labile SOC fractions (i.e., microbial biomass C (MBC), dissolved organic C (DOC), hot-water extractable C (HWC), permanganate-oxidizable C (KMnO4-C), and particulate organic C in the 0–20 cm layer) to the crop rotation systems with the retention of different crop residues over the period of 11 years were specific to the types of the rotation system and closely related to the soil fertility properties. The RP treatment had comparatively higher content of DOC, HWC, MBC, and KMnO4-C than the other treatments in both 0–10 cm and 10–20 cm depths. The RW treatment had higher KMnO4-C content but lower MBC and POC content than the other treatments. The RO treatment had lower MBC content compared to the other treatments, while the opposite results were found in the RG treatment. Furthermore, the DOC content was improved by the winter crop growth. The changes in labile SOC might be attributable to the types of residues retained.

Cadmium (Cd) is a heavy metal that is toxic to plants and animals. Nitrogen (N), the most significant macro-nutrient and a common input for crop production, is often excessively applied than plants' demands by farmers to obtain more economic benefits. Understanding the regulatory mechanisms of N that control Cd uptake, translocation, and accumulation may enable the development of solutions regarding Cd pollution in the trophic chain, a major and global threat to agricultural sustainability and human health. In this review, we clarified that an increased amount of N, regardless of its form, enhances Cd uptake, translocation, and accumulation in plants, and nitrate promotes Cd uptake more than any other N form. We also described that N fertilizer alters the Cd exchange capacity and the bio-available Cd content in soil; regulates nitric oxide induced divalent cation gene expression of Nramp1, HMA2, and IRT1; and changes cell wall isolation, chelation capacity, and oxidative resistance to regulate Cd accumulation in plants. By revealing the integrated interaction effects between Cd accumulation and N fertiliser use, we propose new challenges to investigate the functions and mechanisms of N in Cd-contaminated croplands and develop suitable N-fertilisation protocols to practically reduce food health risks in agricultural food production.

Background Extremely high temperatures are becoming an increasingly severe threat to crop yields. It is well documented that salicylic acid (SA) can enhance the stress tolerance of plants; however, its effect on the reproductive organs of rice plants has not been described before. To investigate the mechanism underlying the SA-mediated alleviation of the heat stress damage to rice pollen viability, a susceptible cultivar (Changyou1) was treated with SA at the pollen mother cell (PMC) meiosis stage and then subjected to heat stress of 40 °C for 10 d until 1d before flowering. Results Under control conditions, no significant difference was found in pollen viability and seed-setting rate in SA treatments. However, under heat stress conditions, SA decreased the accumulation of reactive oxygen species (ROS) in anthers to prevent tapetum programmed cell death (PCD) and degradation. The genes related to tapetum development, such as EAT1 (Eternal Tapetum 1), MIL2 (Microsporeless 2), and DTM1 (Defective Tapetum and Meiocytese 1), were found to be involved in this process. When rice plants were exogenously sprayed with SA or paclobutrazol (PAC, a SA inhibitor) + H2O2 under heat stress, a significantly higher pollen viability was found compared to plants sprayed with H2O, PAC, or SA + dimethylthiourea (DMTU, an H2O2 and OH· scavenger). Additionally, a sharp increase in H2O2 was observed in the SA or PAC+ H2O2 treatment groups compared to other treatments. Conclusion We suggest that H2O2 may play an important role in mediating SA to prevent pollen abortion caused by heat stress through inhibiting the tapetum PCD. Electronic supplementary material The online version of this article (10.1186/s12870-018-1472-5) contains supplementary material, which is available to authorized users.

Rice is most sensitive to heat stress at the flowering stage, with different degrees of heat damage in spikelets and leaves. To investigate the heat damage in spikelets and flag leaves, two rice genotypes, N22 (heat‐tolerant) and GT937 (heat‐sensitive), were subjected to a heat‐stress treatment (40 °C for 15 days). The results showed that more damaging was found in spikelets than in flag leaves and the heat stress significantly decreased the seed‐setting rate by 12.41 % in N22 and by 65.02 % in GT937. However, the difference in the net photosynthetic rate of the flag leaf between heat‐stressed and control was not significant. Moreover, the difference of temperatures in spikelets and flag leaves was attributed to the differences in heat dissipating. Under heat stress, the transpiration rate was significantly higher in flag leaves than in spikelets, and the temperature in flag leaves were at least 4 °C cooler than in spikelets. Although the spikelet temperatures did not differ significantly between the two genotypes under heat stress, spikelets of GT937 were more severely damaged than those of N22, which might result from the differences in the antioxidant capacities between genotypes. Results showed that little difference of superoxide dismutase, peroxidase and catalase activities of spikelets was found in N22, while significant reduction was found in GT937 under heat stress, compared with control. These results suggest that organ temperature is controlled mainly by transpirational cooling, and that heat stress is an indirect result of oxidative stress, rather than a direct result of heat damage.

It is proved that a simple module which is locally finite over the positive part of the Cartan decomposition for a finite-dimensional Lie algebra with triangular decomposition and solvable positive part is a highest weight module, a Whittaker module or a singular Whittaker module. The classification of simple highest weight modules for the Schrodinger algebra follows from the classification of all simple lowest weight module for the Schrodinger algebra given by Dobrev, Doebner and Mrugalla. The simple Whittaker modules for the Schrodinger algebra are classified in this paper. The singular Whittaker vectors for the universal singular Whittaker module are given.

We study the tensor product of a highest weight module with an intermediate series module over the Neveu–Schwarz algebra. If the highest weight module is nontrivial, the weight spaces of such a tensor product are infinite dimensional. We show that such a tensor product is indecomposable. Using a “shifting technique” developed by H. Chen, X. Guo, and K. Zhao for the Virasoro algebra case, we give necessary and sufficient conditions for such a tensor product to be irreducible. Furthermore, we give necessary and sufficient conditions for two such tensor products to be isomorphic.

There are two extensions of Virasoro algebra with particular importance in superstring theory: the Ramond algebra and the Neveu-Schwarz algebra, which are ℤ2-graded extensions of the Virasoro algebra. In this paper, we show that the support of a simple weight module over the Ramond algebra with an infinite-dimensional weight space coincides with the weight lattice and that all intersections of non-trivial weight spaces and odd part or even part of the module are infinite-dimensional. This result together with the one that we have obtained over the Neveu-Schwarz algebra generalizes the result for the Virasoro algebra to the super-Virasoro algebras.