Cropping diversification, especially with legume inclusion, has been shown to improve soil organic carbon (SOC) sequestration. However, it remains unexplored how preceding intercropped leguminous green manure affect microbial activity and necromass C contribution to SOC under reduced nitrogen (N) input in subsequent crop rotations. A six-year field experiment was conducted with treatments including maize monoculture (M) and intercropping with lablab bean as green manure (M/L), followed by rapeseed (R) under zero, 100 % and 65 % of recommended N application. The treatments were designated as M-R0, M-R100, M-R65, and M/L-R65. Soils were collected from 0 to 20 cm topsoil and 20-40 cm subsoil after rapeseed harvest for analysis of SOC fractions, microbial necromass carbon (MNC), extracellular enzyme activities, and microbial community. The results showed that preceding maize/legume intercropping M/L-R65 significantly increased the content of SOC, total N, dissolved organic C and N by 14.3-34.1 % in the topsoil compared to M-R100. This increase was associated with higher microbial necromass C content driven by a shift towards K-strategy microorganisms that produce more recalcitrant necromass compounds. In contrast, subsoil SOC levels remained relatively stable in the M/L-R65, despite an increase in MNC content. The lower soil C/N and dissolved organic C/N ratios in the M/L-R65 treatment endorsed soil N enrichment-induced decomposition of particulate organic C (POC) in the subsoil. This was further corroborated by the strong and direct impacts of soil C to N stoichiometry on microbial C pools revealed by PLS-PM analysis. Microbial C use efficiency (CUE) was higher in reduced N input treatments in the subsoil, but this did not translate to increased SOC in the subsoil layer, likely due to the shift in fungal community towards r-strategists. Overall, the study suggests that preceding legume intercropping enhances SOC sequestration in the topsoil of low-N input rapeseed rotation systems through increased microbial necromass C inputs. Moreover, the responses of SOC pools across soil depths are mediated by shifts in microbial life-history strategies.

Selenium (Se) mitigates heavy metal(loid) toxicity in plants, however, its regulatory effects on photosynthesis and metabolic pathways remain poorly understood. This study investigated the alleviating effects of selenite on cadmium (Cd), lead (Pb), and antimony (Sb) toxicity across three varieties of Brassica campestris L. (V1, V2 and V4) and one Orychophragmus violaceus L. (V3) using physiological, biochemical, and metabolomic approaches. Results revealed variety-dependent mechanisms of Se-mediated detoxification: in resistant varieties (V1), although Se stimulated photosynthetic efficiency (Pn) but inhibited the abundance of most tested fatty acid and terpenes/terpenoids, and induced energy dissipation and exacerbated electron transfer. In addition, Se stimulated purine metabolism, pyrimidine metabolism, phenylpropanoid biosynthesis, and the formation of some flavonoid/flavones. But Se reduced the metabolism of galactose and histidine, and jasmonate formation. Whereas in the sensitive cabbage-type rapeseed (V4), Se rebalanced photosynthetic electron transfer but did not significantly affect Pn. Additionally, Se upregulated the abundance of terpenoids (e.g., gibberellins, abscisic acid), oligopeptides, and DEMs involved in galactose metabolism. But Se restricted the salicylate synthesis, toluene degradation, and the metabolism of purine and histidine. These findings elucidate that the detoxification mechanisms of multiple metal(loid) by Se may be plant variety-dependent.

Leaf mass per area (LMA) and photosynthetic rate (A) explain fast-slow growth strategies in the worldwide leaf economic spectrum. Nitrogen (N) promotes A and rapid growth, while LMA responds to N supply in a genotype specific manner. Structural traits affect the relationship between LMA and A, and we hypothesized that N supply would affect structural traits and thus the coupling between LMA and A. We tested this hypothesis by measuring A, LMA, anatomical traits, and N allocation to various leaf components in nine Brassica napus cultivars with two N supply levels. Mesophyll cell density (ρcell) and palisade tissue thickness (Tp) predominantly influence the variability in LMA. Enhanced Tp increased LMA, chloroplast surface area exposed to intercellular airspace, and N allocation into Rubisco (Nrub), thereby positively affecting mesophyll conductance (gm) and A. Conversely, ρcell promoted LMA but negatively affected Nrub under N deficiency. Enhanced LMA promoted N allocation to cell wall (Ncw), causing decreased Nrub fraction and consequently A. This negative effect was relieved by the positive effect of Tp on A, which coupled the variation of LMA and A. The plasticity of Tp and ρcell regulating gm and the trade-off between Nrub and Ncw provides insights for simultaneous increases in LMA and A to promote rapid growth and resistance.

Ammonium (NH4+-N) is the predominant form of nitrogen (N) fertilizer, but poses a risk of NH4+ toxicity, adversely affecting plant growth. Photosynthesis, which is closely linked to biomass and yield, is inhibited by NH4+ toxicity, but this effect is alleviated with increasing supplied nitrate (NO3--N) fraction. To understand the mechanism behind NO3--N's alleviation of NH4+-N inhibition on photosynthesis, limiting factors for photosynthetic rate (A) and anatomical characteristics of Brassica napus, an essential oil crop that heavily relies on N fertilizer, were measured. Results revealed that the inhibition of NH4+-N toxicity on A and growth was aggravated under NO3--N deprivation. When the proportion of NO3--N was lower than that of NH4+-N, the decrease of A was dominated by mesophyll conductance (g(m)), with its reduction strongly correlated with increased distance between two neighbouring chloroplasts (Dchl-chl) and decreased chloroplast surface area exposed to intercellular airspace per unit leaf area (Sc). NO3--N supply promoted volume fraction of intercellular air space (f(ias)) and mesophyll surface area exposed to intercellular airspace per unit leaf area (S-m), furtherly enhancing Scand facilitating higher gm. Additionally, Dchl-chl, f(ias), and S-m were more closely related to leaf NO3--N concentration than to NH4+-N. Thus, NO3--N plays a crucial role in mitigating NH4+-N toxicity on A by regulating leaf mesophyll arrangement and morphology. Increasing the proportion of NO3--N in fertilizers provides a strategy for crops at the risk of soil NH4+-N toxicity to maintain high A, furtherly promoting yield and N use efficiency.

Harnessing beneficial plant-microbe interactions in the rhizosphere presents a promising strategy for plants to combat unfavorable environment. However, the mechanisms by which rapeseed (Brassica napus L.) genotypes regulate root-associated microbiota through root metabolites under nitrogen (N) deprivation has not been fully explored. To address this issue, we planted rapeseed genotypes with varying tolerance to N deficiency—G364, which is susceptible, and G294 and ZS11, which exhibit tolerance—under both N-starved (N0) and N-sufficient (N1) conditions in pots. As expected, G364 was the most susceptible to N deficiency, experiencing a 30.8 % reduction in dry biomass when subjected to N deprivation. In contrast, G294 exhibited the greatest tolerance to N-deficiency, with only a 14.1 % decline in biomass due to N deficiency, underscoring its superior N utilization efficiency. The rhizosphere bacterial microbiomes of these genotypes exhibited distinct patterns at the rosette stage. Under N deprivation, the bacterial classes that significantly enriched in the rhizosphere of G294 and ZS11 genotypes were Chloroflexia, Bacilli, TK10, Gammaproteobacteria, and Acidimicrobiia. These microbial enrichments were positively correlated with increased biomass and N uptake in rapeseed. Furthermore, the compositional shifts in the rhizosphere bacterial community were associated with greater intensity of metabolites like flavonoids, amines, terpenoids, steroids, hormones and transmitters etc. Taken together, our study underscores the pivotal role of root metabolites in harnessing the beneficial plant–microbe interactions, thereby potentially improving the N use efficiency of rapeseed. This insight is valuable for manipulating the rhizosphere microbiome for breeding crops aimed at developing varieties with enhanced N efficiency.

Improving the nutrient content of red soils in southern China is a priority for efficient rice production there. To assess the effectiveness of oilseed rape as green manure for the improvement of soil phosphorus nutrient supply and rice yield in red soil areas, a long-term field plot experiment was conducted comparing two species of rape, Brassica napus (BN) and Brassica juncea (BJ). The effects of returning oilseed rape on soil phosphorus availability, phosphorus absorption, and yield of subsequent rice under rice-green manure rotation mode were analyzed, using data from the seasons of 2020 to 2021. The study found that compared with winter fallow treatment (WT) and no-tillage treatment (NT), the soil available phosphorus content of BN was increased, and that of BJ was significantly increased. The content of water-soluble inorganic phosphorus of BJ increased, and that of BN increased substantially. Compared with the WT, the soil organic matter content and soil total phosphorus content of BN significantly increased, as did the soil available potassium content of BJ, and the soil total phosphorus content of BJ was significantly increased compared with NT. The soil particulate phosphorus content of BJ and BN was significantly increased by 14.00% and 16.00%, respectively. Compared with the WT, the phosphorus activation coefficient of BJ was significantly increased by 11.41%. The rice plant tiller number under the green manure returning treatment was significantly increased by 43.16% compared with the winter fallow treatment. The green manure returning measures increased rice grain yield by promoting rice tiller numbers; BN increased rice grain yield by 9.91% and BJ by 11.68%. Based on these results, returning oilseed rape green manure could augment the phosphorus nutrients of red soil and promote phosphorus availability. Rice-oilseed rape green manure rotation could increase rice grain yield.

Legume-inclusive cropping is increasingly appreciated for enhancing crop yield and sustainability. However, their impacts on subsequent oilseed rape productivity under reduced nitrogen (N) inputs have not been well explored. In a five-year field rotation experiment, oilseed rape was cultivated with N fertilizer at zero (MN0), recommended (MN100), and 35 % reduction (MN65) following maize monoculture or preceding lablab (Lablab purpureus (L.) Sweet) intercropping in addition to MN65 (IN65). The productivity and stability of subsequent oilseed rape, and relevant indices of soil fertility and N cycling enzymes were investigated. Compared with the MN0 control, the MN100, MN65 and IN65 treatments increased the rapeseed yield by 0.7- to 1.2-fold. Compared with MN100, MN65 decreased rapeseed yield by 21 % and N uptake by 16 % on average across years. However, preceding lablab intercropping (IN65) recovered yield and N uptake. Treatment IN65 increased soil total N content by 7 % and organic matter by 10 % compared to the monoculture treatments, corresponding to 18-25 % increase in the soil quality index by preceding pulse intercropping. Moreover, in parallel with the increase in soil urease activity, the soil nitrate content in IN65 markedly increased by 18-123 % compared with that in the MN65 or MN100 treatments at most stages of oilseed crop growth. Principal component analysis revealed that the IN65 treatment was well distinguished from the three monoculture treatments, which was attributed primarily to soil nitrate, organic matter, nitrate reductase activity, and microbial biomass N. This enhanced N turnover and availability, in turn, largely contributed to N uptake and yield recovery of subsequent rapeseed crops under reduced N input. Consequently, the yield sustainability and stability of rapeseed following lablab intercropping were greater than those following monoculture, as evidenced by the higher sustainability index (64 % vs. 49 %) and lower variation (20 % vs. 32 %). Overall, these findings indicate that lablab and maize intercropping enhances positive legacies for subsequent rapeseed productivity under reduced N inputs.

Improper fertilization has become an essential factor limiting peanut yield and quality improvement. To improve peanut yield and quality, the effects of different fertilizer additives on peanut growth and yield were investigated. In this work, the effects of four fertilizer additives produced by microorganisms (CL, T6, T4, and P1) on peanut growth and yield were evaluated through pot and field trials. The results indicated that all fertilizer additives significantly increased the branch number and biomass of peanuts compared to the control. Additionally, T6 and CL treatments led to significantly higher peanut yields in the field. The aboveground nitrogen concentration of peanuts treated with CL and T6 was also significantly higher than that of the control, while T4 treatment did not show a significant difference. Overall, CL and T6 had the best positive effect on the growth of peanuts. The potential application values of CL and T6 in peanuts showed that fertilizer additives produced by microorganisms could be used as effective measures to achieve highly efficient production in agriculture.

In order to enhance the tolerance of rapeseed respond to low nitrogen（N） stress, this study investigated the effects of melatonin（MT） on N absorption and transport of rapeseed at the seedling stage under N deficiency conditions. The effects of exogenous application of MT on biomass, N uptake and accumulation, as well as the expressions of genes（BnNRT2s and BnAMTs） involved in N absorption and transport were analyzed by pot experiments. Results showed that, exogenous spraying of MT under N deficiency conditions significantly improved the shoots and roots biomass of rapeseed, especially when MT was sprayed at a concentration of 100 μmol/L. And exogenous spraying of MT also significantly increased N accumulation of shoots and roots of rapeseed seedlings. Further analysis found that, expression levels of BnNRT2.1s gene members（except BnNRT2.1a）, BnNRT2.2a, and BnNRT2.4b were up-regulated and reached the highest in roots when MT concentration was 100 μmol/L. And BnNRT2.7s and BnNRT2.5s were up-regulated and reached the highest in leaves when MT concentration was 50 μmol/L（MT50）. Meanwhile, the expression of BnAMT1.1a, BnAMT1.3b, BnAMT1.3c, BnAMT2.2a and BnAMT2.2c genes were significantly up-regulated in junior leaves, senior leaves and roots after exogenous application of MT. The expression of BnAMT1.4a, BnAMT1.4b, BnAMT2.1b, the abundance of BnAMT2.2a and BnAMT2.2b genes were also significantly enhanced in junior and senior leaves. Additionally, except BnAMT1.3b and BnAMT1.3c, all the above genes were expressed at the highest level under MT50 treatment. In conclusion, exogenous spraying of MT might improve N absorption and transport limited N to shoot through enhancing the expression of several BnNRT2s and BnAMTs. Thus exogenous application of MT could promote N absorption and utilization in rapeseed, alleviate low N stress and improve its low N tolerance.

水稻油菜轮作制度是华中地区最具代表性的耕作制度,但水稻收获后的秸秆清理和还田效果会影响后续油菜的播种和收获.利用微生物降解秸秆是解决这一问题的有效途径之一.前期研究发现,粗糙脉孢菌接种至水稻秸秆,培养48 h时秸秆有明显降解现象,因此,本研究通过转录组测序技术研究分析比较接种在PDA培养基上和接种在水稻秸秆上培养48 h时粗糙脉孢菌的差异表达基因,以探讨其降解机理.结果表明,两者间共存在3329个显著差异表达基因,GO(gene ontology)功能注释分析发现,这些基因主要富集在生物过程类,表达差异较大的基因主要参于核苷酸代谢、蛋白质代谢及与内膜系统;KEGG(Kyoto Encyclopedia of Genes and Genomes)通路富集分析发现,这些差异表达基因的功能主要涉及半乳糖代谢、果糖和甘露糖代谢、氧化磷酸化、次生代谢产物的生物合成和核糖体,在这些代谢途径中筛选到的与降解秸秆相关的酶系多数为上调表达.在这些代谢途径中,推测粗糙脉孢菌主要通过半乳糖代谢、果糖和甘露糖代谢来降解水稻秸秆.以上研究可为更高效地利用粗糙脉孢菌降解秸秆提供新的理论依据和一定的技术支持.

Ammonium transporters (AMTs) are plasma membrane proteins mediating ammonium uptake and transport. As such, AMTs play vital roles in ammonium acquisition and mobilization, plant growth and development, and stress and pathogen defense responses. Identification of favorable AMT genotypes is a prime target for crop improvement. However, to date, systematic identification and expression analysis of AMT gene family members has not yet been reported for rapeseed (Brassica napus L.). In this study, 20 AMT genes were identified in a comprehensive search of the B. napus genome, 14 members of AMT1 and 6 members of AMT2. Tissue expression analyses revealed that the 14 AMT genes were primarily expressed in vegetative organs, suggesting that different BnaAMT genes might function in specific tissues at the different development stages. Meanwhile, qRT-PCR analysis found that several BnaAMTs strongly respond to the exogenous N conditions, implying the functional roles of AMT genes in ammonium absorption in rapeseed. Moreover, the rapeseed AMT genes were found to be differentially regulated by N, P, and K deficiency, indicating that crosstalk might exist in response to different stresses. Additionally, the subcellular localization of several BnaAMT proteins was confirmed in Arabidopsis protoplasts, and their functions were studied in detail by heterologous expression in yeast. In summary, our studies revealed the potential roles of BnaAMT genes in N acquisition or transportation and abiotic stress response and could provide valuable resources for revealing the functionality of AMTs in rapeseed.

A coordinated increase in the photosynthetic rate (A) and photosynthetic nitrogen use efficiency (PNUE) is an effective strategy for improving crop yield and nitrogen (N) utilization efficiency. PNUE tends to decrease with increasing N levels, but there are natural variations. Consequently, leaf functional N partitioning in Brassica napus genotypes under different N rates was measured to explore the optimized N allocation model for synchronously increasing A and PNUE values. The results showed that genotypes whose PNUE increased with increasing N supply (PNUE-I) produced an approximate A value with a relatively low leaf N content, owing to reduced storage N (N-store) and close photosynthetic N (N-psn) content. Partial least squares path modeling showed that A was dominated by the N-psn content, and PNUE was directly influenced by A and N-store. The A value increased with the N-psn content until the N-psn content exceeded the threshold value. The boundary line of PNUE varied with the N-psn and N-store proportions, indicating that the optimum N-psn and N-store proportions were 51.6% and 40.3%, respectively. The N-store proportion of PNUE-I was closer to the thresholds and benefited from lower increments in Rubisco content and nonprotein form storage N content with improved N supply. Optimized N-store and N-psn trade-off by regulating increments in N-store content with increased N supply, thereby promoting coordinated increases in A and PNUE.

To clarify the application potential of Neurospora crassa NC-3 strain on rice straw returning, a combination of indoor simulation and pot experiment were conducted to investigate the effects of NC-3 strain on degradation, cellulose, hemicellulosic, lignin, total phenolic acid content of rice straw, germination rate and seedling rate of rapeseed.The results showed that NC-3 strain could rapidly colonize on sterilized rice straw（full of mycelia and spores at 72 h）.Compared with the sterile water, the degradation rate of rice straw in NC-3 strain was increased by 2.3,7.3 and 3.2 percentage points at 7,14 and 21 days, respectively.The contents of cellulose, lignin and total phenolic acid decreased with NC-3 strain by 2.0,10.7,10.4 percentage points, 0.7,0.9,1.3 percentage points and 7.6%,6.9%,6.4%,respectively.The degradation effect of NC-3 strain on cellulose, lignin and total phenolic acid of rice straw mainly occurred in the first two weeks（0—14 days）of straw, and the degradation effect on hemicellulose gradually increased after 14 days of culture.Addition of rice straw significantly reduced the germination rate and seedling rate of rapeseed, and with the increase of straw dosage, the inhibition effect was enhanced, but NC-3 strain could significantly increase the germination rate and seedling rate of rapeseed（3.3 and 9.7 percentage points higher than sterile water in petri dish test, respectively）.In summary, NC-3 strain could effectively accelerate the degradation of rice straw and the transformation of phenolic acids, and effectively improve the germination rate and seedling formation rate of rapeseed.

Peanut (Arachis hypogaea L.) is one of the most important crops produced worldwide. Peanut is the dominant crop in the typical upland red soil areas of China; however, phosphorus bioavailability in red soil is very low, which severely affects peanut production. To improve the phosphorus bioavailability, which substantially promotes the green development of peanut production, a peanut–green manure rotation field experiment was conducted with six treatments (milkvetch; radish; brassica rape; mustard rape; winter fallow and no-tillage), commencing in September 2017 in the red soil area of Jiangxi province, China. The results show that compared with no-tillage (NT) treatments, different green manure returning treatments had significant effects on soil pH, soil phosphorus components and available potassium content. The particulate phosphorus and soil available phosphorus contents in the green manure treatments were significantly higher than those in the winter fallow (WF) treatment. Compared with the WF treatment, the content of particulate phosphorous in brassica rape (BR), radish (R) and milkvetch (MV) treatments was significantly increased by 6.55%, 3.66% and 2.50%, respectively; the available phosphorus content in mustard rape (MR), BR, R and MV was significantly increased by 20.93%, 25.60%, 23.76% and 18.10%, respectively. In addition, the total phosphorus content of peanut shell in the MV and R treatment was significantly higher than that in the WF treatment, increasing by 33.47% and 60.66%, respectively. Compared with the WF treatment, the peanut biomass of MR, BR and R treatments increased significantly by 19.51%, 29.83% and 19.77%, respectively. The total phosphorus accumulation in all green manure treatments was higher than that in the WF treatment, and the MV treatment reached a significant level at 18.83%. Based on these results, the particulate phosphorus (PP) and available phosphorus were significantly affected by different green manure treatments; green manure amendment improves peanut phosphorus uptake. The use of green manure (especially milkvetch and brassica rape) can be recommended to improve phosphorus bioavailability and yield of peanut in red soil areas.

【Objective】The aim of this study was to investigate the effects of nitrogen application on yield formation and nutrient utilization of oilseed (Brassica napus L.) under different cropping systems.【Method】A field experiment was carried out in Huanggang, Hubei Province. An oilseed variety ‘Zhongyouza19’ was used as the material, setting with two cropping systems (rice-oil rotation, RO; soybean-oil rotation, SO) and four nitrogen rates (N0, 0; N1, 90 kg·hm-2; N2, 180 kg·hm-2; N3, 270 kg·hm-2) in this study. The yield and its components, dry matter accumulation, agronomic traits, nitrogen content and seeds quality were measured.【Result】(1) The oilseed yield of SO was significantly higher than that of RO, and the pods per plant, seeds per pod and 1000-seeds weight of oilseed in different cropping systems all tended to increase significantly by increasing the amount of nitrogen. Compared with N0, the seed yield of RO increased by 176.68%, 436.49% and 835.40% under N1, N2 and N3 treatments, respectively, while that of SO increased by 123.96%, 344.46% and 547.25%, respectively. Compared with RO, the seed yield under SO increased by 62.09%, 31.33%, 71.79% and 12.21% under N0, N1, N2 and N3 treatments, respectively. (2) The root crown diameter, plant height, first effective branch height and branch number of SO oilseed were significantly higher than those of RO at maturity stage, and the increase in each agronomic trait index was significant under different cropping systems with the increase in nitrogen application; the root biomass and above-ground biomass of SO were significantly higher than those of RO at all growth stages, but the root shoot ratio was lower than that of RO. The root shoot ratio decreased significantly after seedling stage in both cropping system with increasing nitrogen application. (3) Nitrogen content and nitrogen accumulation in the root, pod shell, stalk and seeds of SO were higher than those in RO, and the increases in nitrogen content and nitrogen accumulation in each part were significant with the increase in nitrogen application; the apparent nitrogen recovery efficiency under SO was higher than that under RO, and the apparent nitrogen recovery efficiency under RO increased with the increase in nitrogen application. (4) Compared with the RO, the soluble sugar content of pod shell under SO was lower, while the amino acid content and amino acid/soluble sugar content were higher with the same nitrogen application. The soluble sugar content decreased, but the amino acid content and amino acid/soluble sugar content increased with the increase of nitrogen application. Therefore, the oil content of oilseed under SO was lower than that under RO due to the limitation of fatty acid synthesis substrate, and the oil content of seeds decreased significantly with the increase of nitrogen application in cropping system. Oil yield was the maximum in both cropping system at 270 kg·hm-2 nitrogen application level, 1 678.60 and 1 665.33 kg·hm-2 for RO, and 1 684.03 and 1 687.10 kg·hm-2 for SO, respectively, but the difference in oil yield between 180 and 270 kg·hm-2 nitrogen application for SO was not significant.【Conclusion】In conclusion, the nitrogen rate for RO could be controlled at about 270 kg·hm-2, but the nitrogen rate for SO could be controlled at about 180 kg·hm-2 to ensure higher nitrogen use efficiency and higher oil yield.

为提高抗寒性,促进油菜种子发芽及幼苗生长,以甘蓝型油菜品种中油杂19为材料,研究外源海藻糖浸种对低温胁迫下油菜种子萌发及幼苗生长的影响,阐明外源海藻糖浸种的寒害缓解作用.结果表明,在低温处理下(10℃),油菜种子萌发受到抑制,发芽势、发芽率、发芽指数及活力指数均显著下降,平均发芽时间显著延长;种子萌发过程中异柠檬酸裂解酶活性显著降低,可溶性糖和可溶性蛋白消耗显著降低,脯氨酸含量增加缓慢;油菜幼苗苗长、主根长及干鲜重均显著降低.而外源海藻糖浸种可以显著提高低温胁迫下油菜种子萌发速率及根系发育,促进幼苗生长,其中以10 mmol/L的海藻糖浸种处理效果最好.10 mmol/L海藻糖浸种可以促进油菜种子可溶性蛋白和可溶性糖的消耗,增加脯氨酸积累,提高异柠檬酸裂解酶的活性,使种子发芽率和发芽势分别提高19.4％和61.8％,平均发芽时间缩短21.7％;同时也可以促进幼苗根系生长,增加养分含量,提高油菜幼苗鲜重.相关分析发现浸种24 h后,可溶性糖和蛋白及脯氨酸含量与各项发芽指标显著相关.综上认为,10 mmol/L海藻糖浸种24 h,可通过促进种子能量代谢和渗透调节,缓解低温对种子萌发的抑制作用,促进油菜生产,提升其抗寒能力.

【Objective】Nitrogen (N) uptake efficiency is one of the important factors affecting crop N efficiency, investigating characteristics of efficient N uptake and transport was the purpose to provide the theoretical basis for improving N efficiency and yield of rapeseed (Brassica napus L.) varieties.【Method】To explore the mechanisms underlying high N uptake and transport in rapeseed, two rapeseed germplasms with contrasting N efficiency (N efficient germplasm ‘498’ and N inefficient germplasm ‘428’) were used in this study under normal N (9.5 mmol·L-1) and low N (0.475 mmol·L-1) conditions at three different growth stages (Phenological growth stages 12, 14 and 16) in hydroponic culture. At the same time, the 15N isotope tracer technique was applied to study the uptake and transport capacity of NO3− and NH4+. Additionally, the expression level of genes (BnNPFs, BnNRT2s and BnAMTs) related to N uptake and transport in rapeseed germplasms with contrasting N efficiency were further analyzed by real-time quantitative PCR (RT-qPCR).【Result】Rapeseed germplasm ‘498’ showed superior advantages in plant growth and root development under different N concentrations, and the root morphological indexes (main root length, total root length, root surface area, root volume and lateral root number), biomass, N accumulation and N uptake efficiency were all significantly greater than those of germplasm ‘428’. 15N isotope tracer test also showed that ‘498’ showed greater advantage in the uptake and accumulation of NO3- and NH4+, especially for NH4+, as indicated by the significant differences in the accumulation of 15NH4+ between two germplasms. The RT-qPCR analysis further found that under normal N conditions, the relative expressions of BnNPF6.3a, BnNRT2.1e, BnNPF7.2a, BnNPF7.2c, BnNPF6.2c, BnAMT1;2a, BnAMT1;3c, BnAMT1;4a, BnAMT2;1a and BnAMT2;1b (involved in the uptake and transport of NO3- and NH4+) was significantly higher in ‘498’ than that in ‘428’. While under low N stress, the relative expressions of BnNRT2.4a, BnNRT2.5a and BnNRT2.5b (involved in NO3- uptake and transport) was significantly lower in the root of ‘498’ than that of ‘428’, but the expression level of BnNPF7.3a and BnNPF6.2c (referred to NO3- transport and redistribution) was significantly higher in ‘498’ than that in ‘428’, as well as the expression level of BnAMT1;1a, BnAMT1;2a, BnAMT1;3c, BnAMT1;4a, BnAMT2;1a and BnAMT2;1b (involved in NH4+ uptake and transport).【Conclusion】Compared with N-inefficient germplasm ‘428’, N-efficient germplasm ‘498’ were superior in root length, root surface area (volume) and lateral root number, additionally with greater ability in N (especially NH4+) uptake and accumulation. Under normal N application conditions, the expression of genes involved in NO3- and NH4+ absorption and transport were relatively higher in ‘498’, while the relative expression of genes involved in the NO3- transport and redistribution as well as NH4+ absorption and transport were significantly higher in ‘498’ than that in ‘428’ under low N stress, illustrating the relative higher N uptake efficiency of ‘498’ possibly linked to the higher expressions of several BnNPFs sand BnAMTs.

Rapeseed (Brassica napus L.) is the major edible oil crop in China, and it is also a kind of crop for land use and maintenance, crop rotation, and fallow. With the promotion of green development in agriculture, rapeseed is highlighted with its high quality as green manure due to the characteristics of great biomass and adaptability. For the different industrial objectives of rapeseed cultivation, the nutrient demand characteristics of the existing rapeseed varieties determine the high recommended fertilization levels, whereas it cannot meet the needs of green manure with low fertilizer input. Therefore, the evaluation and screening of rapeseed germplasms with low nitrogen (N) tolerance can provide material support for breeding rapeseed cultivars as green manure. In this study, 73 rapeseed germplasms were planted at two N levels (low N and normal N) in the field experiment, the potential application as green manure of different rapeseed germplasms were evaluated by fresh weight, nutrient accumulation, and tolerance index at full flowering stage. Results showed that the change of fresh weight per plant for 73 rapeseed germplasms under low N conditions ranged from 29.33 g to 199.33 g, and the variation coefficient was 30.0%. Meanwhile, under low N stress, the change of N accumulation in shoot and root of 73 rapeseed germplasms were ranged from 48.67-360.43 mg and 4.21-67.46 mg per plant, and the variation coefficient were 31.0% and 53.0%, respectively. This mean that there were certain genetic variations biomass and nutrient absorption and accumulation ability among different rapeseed germplasms. Therefore, it was feasible to select the rapeseed germplasm with superior advantages as green manure. According to the comprehensive analysis of N efficiency and tolerance index of different rapeseed germplasms at full-bloom stage, 25 of 73 rapeseed germplasms had relatively strong tolerance to low N, while 17 germplasms had relatively poor tolerance to low N, belonging to low N sensitive type. Further analysis revealed that the fresh weight per plant, N accumulation, and N uptake efficiency of low N tolerance germplasms were significantly greater than those of low N sensitive germplasms under two N treatments, it could be used as potential green manure for further application. According to the calculation, the maximum amount of N returned to the field in the low N tolerance rapeseed germplasm was 80.2 kg hm-2. Above all, the selected germplasms with great low N tolerance could be used as potential green manure rapeseed resources to be reserved and applied. In actual production, to better realize the industrial application goal of “the few fertilizers convert into the more green manure”, the application of low N tolerant rapeseed as green fertilizer can reduce the input of chemical fertilizer.

油菜是我国种植面积最大的油料作物,是国产食用植物油的重要来源.油菜生长过程可以优化土壤结构、增加土壤养分、培肥土壤地力,具有用地养地的特征优势.同时,因其具有较强的环境适应能力,可作为先锋作物改良障碍土壤.然而,近年来由于劳动力不足、种植效益低、农民种植积极性不高等因素,导致冬闲田面积逐年增加,冬季光温水土自然资源未能得到有效利用.而油菜作为冬季种植的油料作物,不与粮争地,是开发利用冬闲田最有潜力的作物.利用冬闲田发展油菜生产,不仅可以提升油料产量,还可以充分发挥其养地优势提高后茬作物产量品质、增加种植收益,对维护我国食用油供给安全、助力粮油兼丰及农业绿色可持续发展具有重要意义.本文结合我国油菜生产现状,针对南方稻区冬闲田油菜轮作的生产发展需要,综述了油菜用地养地(油用或肥用)的作物优势,旨在为因地制宜利用南方冬闲田发展油菜生产助力油料产能提升提供科学依据.

Rapeseed (Brassica napus L.) is an important oil crop species and plays a crucial role in supplying edible oil worldwide. However, rapeseed production in the field is often severely inhibited due to nitrogen (N) deficiency. Metabolites play key roles in plant growth and resistance to environmental stress, but little is known about the differential synthesis and accumulation of metabolites underlying rapeseed adaptation to N deficiency. Here, we studied the phenotypic response and used LC–electrospray ionization (ESI), ESI–MS/MS, and widely untargeted metabolomic approaches to detect differences in rapeseed under normal N (HN) and N-deficient (LN) conditions. The results showed that N deficiency severely inhibited rapeseed shoot growth and promoted rapeseed root architectural changes under LN conditions. In total, 574 metabolites were detected, and there were 175 and 166 differentially accumulated metabolites in the leaves and roots between the HN and LN conditions, respectively. The significantly differentially accumulated metabolites were involved in four primary metabolic pathways, namely, sucrose, phenylalanine, amino acid, and tricarboxylic acid cycle metabolism. Notably, we found that plant hormones have distinct accumulation patterns in rapeseed and coordinate to play crucial roles in both maintaining growth and protecting against damage from plant disease under HN and LN conditions. Moreover, our results indicated that flavonoid compounds, especially anthocyanins and rutin, may play important roles in increasing root cell resistance to oxidative damage and soil pathogen infections. Overall, this work provides valuable information for understanding the overall metabolite changes in rapeseed under N deficiency conditions, which may be beneficial for improving and producing new varieties of rapeseed capable of high yields under low N conditions.