Soil that is naturally rich in selenium (Se) also often accumulates the heavy metal cadmium (Cd), which strongly affects the safe production of agricultural products from soil rich in Se. This study reports a synthetic biology strategy to decouple the uptake of Se from the accumulation of Cd by engineering the rhizosphere microbiome. We demonstrated that overexpression of the high-affinity sulfate transporter gene Sultr1;2 in tomato (Solanum lycopersicum) triggers the specific secretion of N-epsilon-acetyl-L-lysine. This acetylated metabolite acts as a metabolic beacon and selectively recruits Streptomyces to the rhizosphere. We determined that these recruited bacteria function as a bio-shield and mediate the biomineralization of soluble Cd into insoluble Cd selenide precipitates. This change prevents the uptake of Cd by the plant roots while maintaining the bioavailability of Se. This mechanism results in a high-Se/low-Cd crop phenotype. A synthetic community was constructed using strains of Streptomyces that were added to the wild type tomato, and it also enriched the crops with Se and reduced the contents of Cd. The content of Se increased by 31.74%, and that of Cd decreased by 29.54%. These findings identified Sultr1;2 as a gene that shapes the microbiome and offers a novel, microbiome-based solution to the soil rich in Se-Cd with broad implications to safely biofortify the crops and remediate the soil.

Microbial fortification represents a promising approach for selenium biofortification in crops. Building on the previous discovery that Bacillus cereus SESY enhances selenium uptake in Brassica napus, this study employed an integrated multi-omics approach to investigate the mechanism by which B. cereus SESY enhances Se bioavailability in the Brassica napus rhizosphere. Inoculation with B. cereus SESY significantly increased selenium content in Brassica napus roots and shoots in calcareous soil by 42.9% and 21.5%, respectively, and increased the selenium content of shoots in yellow brown soil by 30.7%. B. cereus SESY promoted the transformation of residual Se into bioavailable forms and enriched bacterial taxa with high motility and Se-transforming capacity (e.g., Lysobacter, Rhodanobacter, Sphingomonas and Burkholderiaceae) in rhizosphere soil. Key genes of these bacteria involved in Se metabolism (e.g., trxA, narH, cysE, cysK, metB) and cell motility genes (e.g., FlgG, CheW, FliH) were up-regulated. Core rhizosphere metabolites such as N-formylmethionine and xanthine correlated strongly with enriched bacteria abundance and available Se. Joint application of these metabolites with enriched bacteria increased plant Se content by 144% and rhizosphere soil available Se by 13.4%. These results reveal a metabolite-mediated microbial network that enhances Se mobility and plant uptake, providing a novel strategy for microbiome-driven biofortification.

为阐明甜玉米化肥减量增效的有效途径,研究了不同化肥减量措施对甜玉米产量、品质及土壤养分含量的影响.结果表明,优化施肥(包括推荐施肥和不同梯度有机肥替代化肥)可促进甜玉米增产15.14％～25.31％,等养分量条件下,有机肥替代化肥增产4.42％～8.83％,且有机肥替代15％～30％化肥氮可达到较好的产量水平.优化施肥降低甜玉米果实中硝酸盐和淀粉含量,有机肥替代化肥提高甜玉米果实中VC、可溶性糖和可溶性蛋白含量.优化施肥促进甜玉米干物质量增加21.06％～26.49％,促进氮素、磷素和钾素的养分积累量分别增加20.11％～31.32％、21.20％～29.59％和6.76％～16.84％;有机肥氮素替代化肥氮素达到45％时,甜玉米的氮素积累量比较低.与农民习惯施肥相比,推荐施肥、有机肥替代15％化学氮肥、有机肥替代30％化学氮肥减少化肥用量的同时降低了肥料成本.综合考虑,有机氮肥替代15％～30％化学氮肥的效果最好,建议推广应用.

It is well known that salicylic acid (SA) can help plants tolerate abiotic stresses. Nevertheless, the regulatory functions of SA in plants, such as the response of Fritillaria hupehensis Hsiao et K.C.Hsia to exogenous SA rational application under heavy metal stress, remain unknown. This study aimed to assess the relief effects of SA on the damage of F. hupehensis caused by heavy metal cadmium (Cd), as measured by physiological and biochemical characteristics. The results showed that bulb germination and seedling growth of F. hupehensis Hsiao et k. c. Hsia decreased under different Cd toxicity treatments. The radicle length and mitotic index also significantly decreased under Cd stress (P < 0.05), especially under high concentrations of Cd stress. The bulb germination and seedling growth increased slightly under medium concentration treatment compared to low concentration treatment. Cd toxicity treatment significantly reduced the contents of pigment, protein, and sugar in seedlings compared with the control. The contents of total antioxidants and malondialdehyde in Cd-poisoned seedlings increased significantly. The comprehensive treatment promoted the growth of bulbs and seedlings. As a result of Cd stress, SA application significantly increased the bulb germination rate, radicle length, mitotic index, pigment, protein, and sugar content. Lipid peroxidation and total antioxidants were decreased by comprehensive treatments compared with Cd toxicity treatment. This simple study remarkably broadened our understanding of the application and protection of SA in Cd stress. Bangladesh J. Bot. 52(2): 601-606, 2023 (June) Special

为阐明不同减肥增效模式下土壤和作物各指标的变化规律,采用田间小区试验研究了不同减肥措施对毛白菜产量、品质及土壤理化性质的影响.结果表明,不同化肥减量措施中推荐施肥的毛白菜产量最高,为31945 kg/hm2,减肥增效措施下,毛白菜的产量比农民习惯种植增加30.85％～43.26％,叶片中的硝酸盐含量降低16.54％～28.33％,可溶性蛋白质含量增加4.96％～11.83％,维生素C和可溶性糖含量无明显变化,其中施用有机肥替代化肥的措施毛白菜品质最佳.减肥后毛白菜的氮素积累量增加13.20％～25.70％,磷素和钾素积累量无明显差异.施用水溶肥的农学效率为95.39 kg/kg,明显高于其他处理,农民习惯施肥的农学效率最低,仅为24.23 kg/kg.施肥能改善土壤理化性质,但一季毛白菜种植对土壤的pH和EC值无明显影响,施用有机肥后土壤中有机质含量、矿质态氮、有效磷和速效钾含量也明显高于其他施肥处理.综上所述,综合考虑毛白菜产量品质、肥料农学效率和培肥土壤,施用有机肥和水溶肥可以达到较好的效果.

The samples of soil(0～20 cm)and agricultural products of facility cultivation watermelon[Citrullus lanatus(Thunb.)Mat-sum.&Nakai]were collected from major agricultural production areas in Wuhan City,and the physical and chemical indexes,the number of microorganisms of soil,and the quality indexes of agricultural products were detected.The results showed that the spatial variation of soil pH was from 4.91 to 7.16,and the variation of organic matter content was from 9.43 g/kg to 30.75 g/kg.The content of nitrate nitrogen in planting soil was very rich,and the content of available phosphorus and available potassium was at a high level.The soil bulk density and soil compactness were relatively close,and the soil water holding capacity in the field was different with different methods.The quantity of fungi in soil under facility cultivation did not change much,while the number of bacteria and actinomycetes fluctuated obviously.The soil health evaluation indexes of facility cultivation watermelon in Wuhan City were screened by principal component analysis method,and pH,available potassium,organic matter content,nitrate nitrogen,field water holding capacity and bacterial quantity were selected as evaluation indexes.

为探究适宜武汉市设施苋菜生产中有机肥替代化学氮肥的最佳用量,采用田间试验研究不同比例有机肥氮替代化肥氮对设施苋菜产量、品质和氮素利用率的影响.结果表明,在推荐施肥(OPT)用氮量基础上,随着有机肥氮替代比例的增加苋菜产量呈先增后减趋势,当有机肥氮替代30％化肥氮(OPT-30％M)时,苋菜产量最高,与农民习惯施肥(FP)相比,增产3.07％.有机肥的应用显著提高了苋菜的可溶性糖、可溶性蛋白质、维生素C含量,降低了苋菜的硝酸盐含量,OPT-30％M处理苋菜的营养品质最好.在氮素利用方面,OPT-15％M处理的苋菜的吸氮量和氮肥利用率最大,OPT-30％M处理的苋菜氮肥农学效率和氮肥偏生产力最高,分别达43.03 kg/kg和501.93 kg/kg.综上,在武汉市设施苋菜生产中,有机肥氮替代15％～30％的化肥氮较适宜,既能在保持产量提升的基础上降低化肥用量,又能提高氮肥利用效率.

为阐明不同减肥增效模式下土壤和作物各指标的变化规律,采用田间小区试验研究了不同减肥措施对生菜产量、品质及土壤理化性质变化的影响.试验结果表明,不同化肥减量措施中,推荐施肥的生菜产量最高,为2907 kg/667 m2.减肥增效措施下,生菜产量比习惯施肥增加19.83％～76.82％,叶片硝酸含量降低47.49％～63.08％,VC含量增加9.08％～11.25％,可溶性糖含量增加24.84％～29.94％,可溶性蛋白含量增加2.38％～5.94％.其中微生物菌肥替代化肥措施生菜可溶性糖含量最高,有机肥代替化肥措施生菜其他品质最佳,但2个处理品质指标均无显著差异.减肥后生菜氮素积累量增加16.57％～69.82％,磷素积累量增加-1.47％～51.47％,钾素积累量增加0.07％～35.96％.施肥能改善土壤理化性状,但一季生菜种植对土壤pH值和容重无显著影响,施用有机肥后土壤中有机质含量显著高于其他施肥处理,化肥减量处理均显著提高了土壤细菌和放线菌含量,降低了土壤真菌数量,其中施用微生物菌肥效果最明显.综上所述,综合考虑生菜产量品质、肥料农学效率和培肥土壤,推荐施用有机肥和微生物菌肥.

[目的]分析'凤丹'不同器官中氮、磷、钾元素的含量及积累量的年变化规律,探讨'凤丹'各器官氮、磷、钾化学计量特征及在各器官中的分配特性,揭示'凤丹'不同生育期养分吸收和积累规律,以期为油用牡丹合理施肥提供科学依据.[方法]以油用牡丹'凤丹'为材料,采用刨根法在'凤丹'不同生育期取样,将植株按根、老茎、嫩茎、叶柄、叶片、果实、花、花蕾、芽等器官分开,并测定各器官氮、磷、钾元素的含量.[结果]'凤丹'对氮、磷、钾元素的年吸收量分别为4.99、1.11、4.10 g/株,氮、磷、钾吸收量之比约为4.5:1:3.7.随生育期延长,氮、磷2种元素在植株各器官中分配比例的变化趋势较为一致.在'凤丹'中氮、磷元素平均分配比例从高到低的主要分布区域依次为根、果实、叶片,钾元素的平均分配比例从高到低依次为果实、根、嫩茎.现蕾期至大风铃期,植株对氮、磷元素的养分需求量最大;大风铃期至花期,氮、磷元素逐渐在叶片中积累.花期至果实发育期,植株对钾元素的需求量最高;果实发育期至籽粒成熟期,植株地上部与地下部钾元素积累量的比值增加,且果实对钾的需求量最大.在'凤丹'整个生育期内,植株各器官氮磷比为2.39～11.53,氮钾比为0.35～7.74,钾磷比为0.85～21.02.[结论]影响油用牡丹'凤丹'生长的主要限制因素是氮,其次是钾;且花期宜重施氮、磷肥;在果实成熟期宜追施氮、磷肥,并重施钾肥,为种子发育提供物质基础.

为阐明不同施肥模式下土壤和作物各指标的变化规律,研究了不同施肥处理对甜瓜产量、品质及土壤理化性质的影响.试验结果表明,推荐施肥处理(T2)的甜瓜产量最高,为3781 kg/667 m2;相比习惯施肥,优化施肥(配方施肥T2和有机肥替代化肥T3)处理的甜瓜产量增加13.43％～17.28％,果实中的硝酸含量降低24.52％～37.80％,VC含量增加10.38％～29.04％,可溶性蛋白含量增加5.41％～35.81％,可溶性蛋白含量均增加5.08％,其中有机肥替代化肥降低硝酸盐含量效果最明显,甜瓜品质最佳.推荐施肥处理的甜瓜藤蔓的氮素和钾素积累量最大,有机肥替代化肥处理的氮素和钾素积累量最低,所有施肥处理的磷素积累量无显著差异.有机肥替代化肥处理土壤中有机质含量明显高于其他施肥处理;优化施肥可降低土壤中氮素和磷素的积累、提高钾素含量,提高土壤细菌和放线菌含量,降低土壤真菌的数量.综合考虑甜瓜产量、品质和土壤理化性状,推荐在甜瓜种植中配合施用有机、无机肥料.

Lettuce (Lactuca sativa L.), a popular edible vegetable, is highly responsive to mineral fertilizers. A two-year field trial was carried out to determine how nitrogen (N), phosphorous (P), and potassium (K) application ratios affected lettuce growth, yield, and quality. Within a certain range of nutrient application rate, the plant height, stem diameter, yield, and the concentrations of vitamin C and soluble sugar were higher than those without fertilization. Compared with no fertilization condition, the yield increased approximately 13.56–22.03%, 15.15–42.42% and 7.14–10.32% under increased N, P, and K application conditions, respectively. Furthermore, substantial quadratic parabola relationships were observed between lettuce yield and fertilizer application amounts as well as most quality traits. The nitrate concentration was proportional to the N fertilization rate, while the concentrations of soluble sugar and vitamin C positively correlated with N and P application ratios, respectively. The lettuce leaves had the largest N (60.59%) and K (52.25%) accumulations, whereas the lettuce stem had the highest P (46.33%) accumulation. Above all, the optimal N, P, and K application amounts for lettuce were 315 kg N ha−1, 210 kg P2O5 ha−1, and 285 kg K2O ha−1, respectively.

土壤酸碱性(pH)是土壤理化性质重要的指标之一,对种植土壤所含的养分形态以及有效性具有重要影响.选取5种不同用途的耕地,分别采用国际和国内标准测定pH,并研究了影响测定结果的因素和2种标准之间的差异.结果 表明,pH测定主要受水土比的影响,振荡时间和过滤对测定结果无显著影响;2个标准之间具有良好的相关性,且浸提液经过滤后,测试液大部分处于澄清状态,仪器测试稳定时间缩短,重复性好.

十字花科根肿病的发生,严重阻碍我国十字花科作物的产业发展.本文综述了土壤湿度、温度、酸碱度、营养元素、微生物对十字花科根肿病发病的影响,以期为十字花科根肿病的综合防治提供理论依据.

Quinoa is a new crop with great potential in the world. Micronutrients are vital components for balances both growth and development in plants. An experiment was designed for the sake of researching the impacts of MnSO4 on output and quality parameters of Quinoa strains in Wuhan. Four repetitions stochastic complete block design is used for the partition layout. Major zones were MnSO4 (contains 28% pure manganese) (2, 4 and 6 g·m−2), and sub-zones were Quinoa cultivars (L-1, L-2 and L-3). The meaningful influence of MnSO4 on the number of fertile ears, the amount of seeds in each ear, the weight of a thousand seeds, grain output, the contents of proteins and manganese in grain. The significant influence of cultivar on number of fertile ears, the weight of a thousand grains, grain output and protein content. The highest values of fertile ear, amount of grain, the weight of a thousand grains, harvest index, grain output, the contents of grain proteins and Mn were achieved in applying 6 g MnSO4 per m2. In addition, the highest amount of fertile ears, amount of grains per ear, grain harvest and grain manganese content were related to“L-3”cultivar. The results show that cultivation of“L-3”cultivar and application of 6 g MnSO4 per m2 is recommended for Wuhan.

通过田间小区试验,监测和诊断3种不同施肥处理对辣椒-甘蓝轮作模式土壤质量的影响,为新型土壤诊断技术在农业生产中的应用提供依据.结果表明,通过对2轮作物的土壤理化性状监测与诊断,辣椒季和甘蓝季的土壤物理指标变化趋势基本一致,施肥能改善土壤物理性质,但推荐施肥(OPT)处理效果更佳;与不施肥对照(CK)相比,OPT处理显著降低了土壤容重,提高了土壤孔隙度、饱和含水量和田间持水量(P<0.05).施肥处理都有土壤酸化现象,习惯施肥(FP)处理最显著,土壤pH比CK降低了12.41％.各处理的养分含量都随着种植时间的延长呈增加现象,2轮作物种完后FP处理和OPT处理的电导率(EC)、全氮含量和阳离子交换量(CEC)都显著高于CK(P<0.05),交换性钙、交换性镁含量与CK差异不显著(P>0.05);OPT处理土壤有机质含量显著高于FP处理和CK(P<0.05),比CK提高了50.68％.由此可知,用有机肥替代部分化肥可以改善土壤质量.

以武汉市江夏区农田土壤为研究对象,共采集149个土壤样品,分析其中8种重金属(Pb、Cd、Cr、Hg、As、Ni、Cu和Zn)的含量,以土壤环境质量农用地土壤污染风险管控标准(试行)为评价基准值,采用单因子污染指数和内梅罗综合污染指数评价该地区土壤农田重金属污染状况.结果 表明,江夏区农田土壤半数以上处于清洁水平,存在的污染主要为Cd污染,40.27％的农田土壤处于Cd污染状态,1％左右的农田土壤分别处于As、Ni、Zn污染状态,未发现农田土壤受到Cr、Cu、Hg和Pb的污染.

为探讨不同种植年限和栽培方式对土壤重金属累积量及其生物有效性的影响,研究了种植年限低于5、5～10、10～15年及15～20年的菜田土壤中8种重金属元素(As、Cd、Cr、Cu、Ni、Pb、Zn、Hg)的含量及其生物有效性系数,同时分析了露地和设施2种栽培方式下土壤重金属含量和生物有效性系数.结果表明,土壤中As、Cd、Ni、Pb的含量随种植年限的增加而递增,Cd、Cr、Cu、Pb、Zn的有效态含量和生物有效性系数在种植年限为10～15年时分别最高和最大,土壤中As、Cd、Hg、Ni含量露地栽培高于设施栽培,Cr、Cu、Pb、Zn的含量设施栽培高于露地栽培;土壤中Ni的生物有效性系数露地栽培高于设施栽培,As、Cr、Cd、Cu、Hg、Pb、Zn的生物有效性系数设施栽培高于露地栽培.种植叶菜类土壤中As、Cr、Cu、Pb、Zn的含量平均值高于种植瓜果类和根茎类,Hg含量的平均值在种植瓜果类蔬菜的土壤中最高,Cd和Ni的含量平均值在种植根茎类蔬菜的土壤中最高.

为了获取适用于生菜(Lactucas sativa L.var.ramosa Hort.)生产的优质有机钾肥,设计了盆栽试验来研究施用不同种类的有机钾肥对生菜产量、品质及土壤微生物的影响.结果 表明,施用钾肥能明显提高生菜的产量和品质,且明显改善了土壤酶活性、微生物数量和养分状况.在等施钾量情况下,化肥钾和沼液钾1∶1(T4)配施可以明显提高生菜的产量,比其他施钾处理增产6.34％～30.53％;化肥钾和生物菌肥钾1∶1处理的生菜维生素C和可溶性糖含量最高,T4次之.化肥钾和玉米钾或水稻秸秆钾1∶1配施可以显著改良土壤状况,其土壤酶活性和微生物状况均明显优于其他处理,化肥钾和沼液配施次之.因此,生菜种植中可以选择沼液或秸秆作为有机钾肥的来源.

为研究锌缺乏或过量对藜麦生长及光合作用的影响,以台湾红藜幼苗为供试材料,采用营养液培养法,分别进行锌缺乏(0μmol/L)和锌过量(1000μmol/L)2个处理下藜麦幼苗生长指标和光合特性指标的测定和分析.结果表明:在缺锌和锌过量胁迫8 d后,锌缺乏和过量都会抑制藜麦幼苗地上部生长,降低植株光合作用速率,从而减少干物质积累;锌过量还会显著抑制幼苗根系生长,减少色素含量和PSⅡ的最大光化学效率.

以武汉市东湖高新区农田土壤为研究对象,共采集58个土壤样品,分析8种重金属(Pb、Cd、Cr、Hg、As、Ni、Cu、Zn)的含量,以土壤环境质量农用地土壤污染风险管控标准(试行)为评价基准值,采用单因子污染指数和内梅罗综合污染指数评价该地区土壤农田重金属污染状况.结果表明,东湖高新区农田土壤总体处于清洁水平,小范围(1.72％)存在Cd轻度污染,未发现农田土壤受到As、Pb、Ni、Cr、Cu、Hg、Pb的污染.