摘要：描述了印度北部比拉斯布尔区喜马偕尔邦Haritalyangar地区中西瓦利克的猪类化石 上、下颌及牙齿材料。Haritalyangar地区以晚中新世动物群、古人类和其他灵长类动物的 多样性而闻名。研究材料为作者之一(ARS)在该地区多次野外季采集的猪类化石；猪类化 石地点和最近报道的长鼻类化石地点(含古猿化石地点)也被绘制在地图上。这些化石地点 广泛分布于Makkan Khad到 Sir Khad区域内的“Lower Alternations”层和“Upper Alternations” 层。猪类化石被鉴定为三个属：Propotamochoerus (P. hysudricus)、Hippopotamodon (H. sivalense) 和Yunnanochoerus (Y. dangari)。 Propotamochoerus hysudricus 为中西瓦利克最 常见的化石猪类，新发现的Yunnanochoerus dangari化石进一步证明这种古猪类化石仅在 Haritalyangar地区有少量遗存。Haritalyangar地区新发现的猪类化石组成与巴基斯坦的Nagri 动物群相近。基于猪类化石进行的的Potwar高原年代地层学对比表明，Haritalyangar地区的 “Lower Alternations”层的年龄范围为~10–9 Ma, 与最新的磁极性地层学年代范围很接近。
摘要：Drought is one of the most serious abiotic stresses which also shifts the composition of root associated microbiomes. However, there is a lack of genetic evidence regarding whether and how plant genetic effects positively reshape drought induced microbiome changes. Root hairs play essential roles in water uptaking, but whether root hairs also orchestrate microbiome re-shaping process during drought stress is unknown. By utilizing genetic mutants with enhanced or decreased root hair densities, we detected a significant effect of plant genetic effect on drought induced microbiome changes. In addition, the hairy mutant (gl2) triggers a deterministic process during drought induced microbiome re-assembly, which further confirms the involvement of host effects in re-shaping drought induced microbiome changes. Rhizobiaceae strains were detected as key biomarker species positively correlated with root hair densities. Moreover, the gl2 mutant also shapes more complex microbiome co-occurrence networks, with more Rhizobiaceae hubs. Our findings unveil the novel roles of root hairs in shaping microbiome structure and network interactions upon drought stress, particularly through regulating the abundance and network centrality of Rhizobiaceae strains. Root hair related mutants also broadly affect root metabolome upon drought stress. Understanding the physiological and microbial ecological basis of host mediated microbiome re-shaping under drought helps develop microbiome engineering approaches to combat climate changes.
摘要：Endophytes, as crucial components of plant microbial communities, significantly contribute to enhancing the absorption of nutrients such as nitrogen and phosphorus by their hosts, promote plant growth, and degrade pathogenic fungal mycelia. In this study, an experiment was conducted in August 2022 to explore the growth-promoting potential of endophytic bacterial strains isolated from two medical plant species, Thymus altaicus and Salvia deserta, using a series of screening media. Plant samples of Thymus altaicus and Salvia deserta were collected from Zhaosu County and Habahe County in Xinjiang Uygur Autonomous Region, China, in July 2021. Additionally, the inhibitory effects of endophytic bacterial strains on the four pathogenic fungi (Fusarium oxysporum, Fulvia fulva, Alternaria solani, and Valsa mali) were determined through the plate confrontation method. A total of 80 endophytic bacterial strains were isolated from Thymus altaicus, while a total of 60 endophytic bacterial strains were isolated from Salvia deserta. The endophytic bacterial strains from both Thymus altaicus and Salvia deserta exhibited plant growth-promoting properties. Specifically, the strains of Bacillus sp. TR002, Bacillus sp. TR005, Microbacterium sp. TSB5, and Rhodococcus sp. TR013 demonstrated strong cellulase-producing activity, siderophore-producing activity, phosphate solubilization activity, and nitrogen-fixing activity, respectively. Out of 140 endophytic bacterial strains isolated from Thymus altaicus and Salvia deserta, 104 strains displayed anti-fungal activity against Fulvia fulva, Alternaria solani, Fusarium oxysporum, and Valsa mali. Furthermore, the strains of Bacillus sp. TR005, Bacillus sp. TS003, and Bacillus sp. TSB7 exhibited robust inhibition rates against all the four pathogenic fungi. In conclusion, the endophytic bacterial strains from Thymus altaicus and Salvia deserta possess both plant growth-promoting and anti-fungal properties, making them promising candidates for future development as growth-promoting agents and biocontrol tools for plant diseases.
摘要：Mangrove forests are valuable resources in tropical and subtropical regions, which have been faced dieback due to various human activities including rapid expansion of shrimp farming, urban development, and pollution, as well as natural factors such as rising sea level, increasing air temperature, drought, and sharp decrease in rainfall. However, the mechanisms of dieback of mangrove forests are not well understood. Therefore, this research aimed to assess the vegetative, chemical, and physiological status of grey mangrove (Avicennia marina (Forsk.) Vierh.) forests at different intensities of dieback in the Hormozgan Province, Iran. A total of 40 plots categorized into four dieback intensities (severe, medium, low, and control) were randomly selected for monitoring, and various parameters related to vegetative, chemical, and physiological status of grey mangrove forests were examined. The results revealed that the control group had the highest tree density, seedling density, vitality levels, aerial root density, and aerial root height. Generally, as dieback severity increased, a decrease in demographic and vegetative parameters of trees and seedlings was observed in the dieback treatments. The amounts of heavy metals (lead, cadmium, and nickel) in the sediment, roots, and leaves of grey mangrove trees at different dieback levels indicated that lead levels were the highest in the sediment, roots, and leaves in the severe dieback treatment. At the same time, the control had the lowest values. Cadmium concentrations in the sediment followed the pattern of severe dieback>moderate dieback>low dieback>control with no significant differences in the roots and leaves. Nickel amounts in all three parts, i.e., sediment, roots, and leaves showed the highest levels in the severe dieback treatment. Furthermore, metal level analysis in the organs of grey mangrove trees at different dieback levels revealed that lead and nickel were more abundant in the root organ compared with the leaves. In contrast, the leaf organ exhibited the highest cadmium levels. Dieback significantly impacted water electrical conductivity (EC), soil organic carbon (SOC), and chlorophyll a, b, and total chlorophyll contents, with the highest values observed in the severe dieback treatment. However, no significant differences were observed in acidity and carotenoid levels. In conclusion, sediment erosion and heavy metal accumulation were critical contributors to dieback of grey mangrove trees, affecting their physiological, vegetative, and plant production characteristics. As the ability of these plants to rehabilitate has diminished, effective management planning is imperative in dieback-affected areas.
摘要：The plantation of non-native species is one of the most expensive ecological restoration measures in arid and semi-arid areas, while its impacts on local communities are largely ignored. This study assessed the rate of change and the dynamic degree of the economic values of ecosystem services related to local conservation (water yield, stocking rate and aesthetic value) and preserving the future (carbon sequestration, soil protection, soil stability and habitat provision) to determine the restoration success of the plantation of non-native species Haloxylon ammodendron (C.A.Mey.) Bunge ex Fenzl (15- and 30-year-old) in parts of arid rangelands of Bardsir region, Kerman Province, Iran. We investigated the impacts of the two plantations on the seven ecosystem services and ecosystem structures (horizontal and vertical structures, vegetation composition and species diversity) based on field sampling and measurements at four sampling sites (i.e., control, degraded, and 15- and 30-year-old plantation sites) in spring and summer of 2022. The restoration success of the plantation of non-native species was then examined by assessing the rate of change and the dynamic degree of the total economic value of all ecosystem services as well as the rate of change and the dynamic degree of the economic values of ecosystem services for the two groups (local conservation and preserving the future). Although the plantation of non-native species H. ammodendron enormously improved the vertical and horizontal structures of ecosystems, it failed to increase species diversity and richness fully. Further, despite the plantation of non-native species H. ammodendron had significantly increased the economic values of all ecosystem services, it was only quite successful in restoring carbon sequestration. Path analysis showed that plantation age had a significant impact on restoration success directly and indirectly (through changing ecosystem structures and services). The dynamic degree of the economic values of ecosystem services related to local conservation and preserving the future at the 15- and 30-year-old plantation sites indicated that the two plantations successfully restored the ecosystem services related to preserving the future. The presented method can help managers select the best restoration practices and predict their ecological-social success, especially for the plantation of high-risk non-native species in arid and semi-arid areas.
摘要：The adenosine A3 receptor (A3AR) belongs to a subfamily of G protein-coupled receptors and is an important therapeutic target for conditions including inflammation and cancer. The clinical compounds CF101 and CF102 are potent and selective A3AR agonists, but the structural basis of their recognition was unknown. Here we present the cryogenic electron microscopy structures of the full-length human A3AR bound to CF101 and CF102 at 3.3-3.2 Å resolution in complex with heterotrimeric Gi protein. These agonists bind within the orthosteric pocket, with their adenine components engaging in conserved interactions while their substituted 3-iodobenzyl groups exhibit different orientations. Swapping extracellular loop 3 (ECL3) of A3AR onto other adenosine receptor subtypes enabled CF101/CF102 binding and receptor activaton, and mutations in key residues, including His3.37, Ser5.42 and Ser6.52 that form a unique subpocket in A3AR, abolished receptor activation, highlighting these structural elements are critical for ligand selectivity. Compared to inactive A2AAR, the A3AR structures reveal conserved mechanism of receptor activation, including an outward shift of TM6. These structures provide key insights into molecular recognition and signaling mechanisms of A3AR, which should aid rational design of subtype-selective ligands targeting this important class of adenosine receptors.
摘要：半耳箬竹 Indocalamus semifalcatus (H. R. Zhao et Y. L. Yang) T. P. Yi 在原始文献中 仅有部分营养器官的描述。该文通过野外居群调查、室内体视解剖和扫描电子显微镜观察， 新增了半耳箬竹的花器官描述和叶下表皮微形态特征，完善了其营养器官的性状描述，更新 了其地理分布。结果表明：(1)繁殖器官性状：花序为圆锥状，小穗及小穗轴密被白色短柔 毛，颖片、外稃及内稃光滑无毛，雄蕊3 枚，花药紫红色，柱头2，白色，羽毛状；(2)营养 体性状：秆高达4.5 m，径达2 cm，箨耳半镰形或微弱，箨片直立紧贴秆，叶耳微弱或无， 叶舌上具较发达的纤毛；叶片两面同色且无毛；(3)叶下表皮微形态特征：气孔器凹陷不可 见，8~10 个长乳突平铺覆盖气孔，硅质体马鞍形，未见有大毛和刺毛；(4)新分布区域1 个， 即贵州省贵阳市观音山。该种与箬叶竹(Indocalamus longiauritus Hand.-Mazz.)最为相似，主 要区别在于该种的箨鞘和叶鞘上具有半镰形的箨耳或箨耳缺失，秆高达4~5 m，径达2 cm。
摘要：经对2019 年至2022 年期间在广西百色、桂林、河池和南宁等地采集的苔类和角苔 类植物标本的研究，共发现10 个广西新记录种，即宽瓣钱苔（Riccia cavernosa Hoffm.）、 日本钱苔（R. nipponica S. Hatt.）、疏叶假护蒴苔 Metacalypogeia alternifolia (Nees) Grolle 、 卵叶鞭苔（Bazzania angustistipula N. Kitag.）、异苞唇鳞苔（Cheilolejeunea kitagawae W. Ye & R.L. Zhu）、条瓣疣鳞苔 Cololejeunea magnistyla (Horik.) Mizut. 、管叶苔 Colura calyptrifolia (Hook.) Dumort. 、凹瓣细鳞苔（Lejeunea convexiloba M.L. So & R.L. Zhu）、台湾角苔 （Anthoceros angustus Steph.）、微小角苔（A. subtilis Steph.），其中管叶苔是中国大陆首次 报道，假护蒴苔属（Metacalypogeia）是广西新记录属。文中列出了新记录种的主要识别特 征、标本信息和地理分布等信息，并提供了图版。该研究结果进一步丰富了广西及中国的苔 藓植物的多样性研究本底资料。
摘要：兜兰属的分类系统学问题争议较大，亟待更多资料澄清。该文利用体式解剖镜和石 蜡切片技术观察了紫纹兜兰的花结构和双雄蕊花药发育特征，为兜兰属及其所在的杓兰亚科 的分类学提供新资料。结果表明：（1）花形态特征支持将紫纹兜兰放置于兜兰亚属的单花 斑叶组，包括萼片具脉纹、花瓣长圆形带黑褐斑，唇瓣具直立的耳状结构，退化雄蕊新月形 等。（2）花药原基分化出一对侧生并列的药室，花药室中央分化出一条不完全贯穿的不育 隔膜组织，将其分化为两个小孢子囊。在花药成熟时，不育隔膜组织被降解吸收，两个花粉 囊通过次生融合形成一枚马鞍形的黏性花粉团。（3）发育完整的花药壁有4 层，由外到内 分别为表皮、药室内壁、中层和绒毡层，符合单子叶型花药壁。花药壁具绒毡层和内绒毡层， 均为2 核。在2-细胞花粉时期，中层和绒毡层发生降解，药室内壁发生纤维状加厚。（4） 小孢子母细胞经同时型胞质分裂形成不同排列方式的小孢子四分体，包括正四面体、左右对 称和十字交叉型，且同一药室的小孢子母细胞减数分裂不同步现象明显。（5）在雄配子体 发育阶段，小孢子或保持在四分体内或从四分体中游离出来，经有丝分裂发育为2-细胞型 花粉，形成具有黏性的四合花粉或花粉粒。结合现有资料，该文比较分析了紫纹兜兰不完全 贯穿的不育隔膜组织、单子叶型花药壁、具2 核的绒毡层和内绒毡层、同时型胞质分裂和黏 性花药等特征的分类学意义，为理解兜兰属及杓兰亚科的分类学和保护生物学提供新资料。
摘要：植物蜡酯合成酶催化长链醇和长链脂肪酸合成蜡酯，对植物蜡质合成及其抗旱、抗致病菌袭击和 紫外辐射、抗寒和昆虫侵害等环境胁迫具有非常重要的作用；镉是环境中含量最高的有毒重金属之一，严 重威胁植物生长发育、质量、产量和食用安全。为研究地黄蜡酯合成酶基因镉胁迫表达，该文从地黄全长 转录组测序数据中鉴定其成员，并用生物信息学技术与qRT-PCR 对其编码蛋白质的理化性质、系统进化和 保守结构域及其组织表达与镉胁迫表达进行分析。结果表明：(1)鉴定出两个蜡酯合成酶基因RgOATWSD1 与RgOATWSD2；其编码蛋白质的的长度、理论等电点和相对分子量依次为463 aa 与473 aa、8.86 与9.34、 51.31 kD 与52.49 kD，均为不稳定蛋白。(2)均具有acyl_WS_DGAT 保守域与DUF1289 超家族，前者占其 氨基酸序列的92.65%～94.50%。(3)均定位于内质网中，二级结构以无规卷曲与α螺旋为主；RgOATWSD1 为跨膜蛋白，而RgOATWSD2 不是。(4)均在地黄根、茎与叶中差异表达。(5)其表达均受镉胁迫诱导，但 其表达变化趋势不同。该研究鉴定了两个镉胁迫应答反应的蜡酯合成酶基因，为地黄RgOATWSD 的镉 胁迫表达及功能研究奠定了基础。
摘要：为研究檀香NDH 脱氢酶基因的功能和调控机制，以檀香心材为材料，利用RACE 技术克隆SaNDH6 基因的全长序列，利用实时荧光定量PCR（RT-qPCR）技术分析其组织 和激素处理后的表达模式，在拟南芥原生质体观测其亚细胞定位，利用PlantCARE 分析 SaNDH6 起始密码子ATG 上游2 kb 的启动子序列，同时运用PlantRegMap 预测可能与其结 合的转录因子。结果表明：（1）SaNDH6 编码303 个氨基酸，为疏水蛋白，亚细胞定位于 叶绿体。（2）进化树分析表明，檀香SaNDH6 与木本植物NDH6 进化关系较近。（3）PlantCARE 分析发现，SaNDH6 启动子中除含有ACE、AE-box、Box 4、G-Box 和GT1-motif 等大量光 响应元件外，同时还有茉莉酸甲酯（MeJA）反应元件CGTCA-motif 和TGACG-motif，赤霉 素（GA）响应元件P-box，以及防御和胁迫响应元件TC-rich repeats 等。（4）通过PlantRegMap 分析发现，有76 个转录因子可能与SaNDH6 启动子结合，其中ERF 家族最多，达到了40 个。（5）SaNDH6 在檀香的根、心材、叶片和愈伤组织中均有表达，其中在叶片中的表达 量较高；用110-4 mol·L-1 的MeJA 和GA3 分别处理檀香愈伤组织后，SaNDH6 的表达均显 著升高。综上结果表明，檀香SaNDH6 为核基因编码的蛋白，受光和激素等诱导表达，可 能参与檀香逆境胁迫反应的过程。
摘要：为改良粗肋草叶色和优化粗肋草设施栽培体系，该研究以吉利红粗肋草水培苗为试验材料，设置6 种 光质（白光，R∶B=1∶1，R∶B=1∶2，R∶B=2∶1，R∶B=1∶3，R∶B=3∶1，其中R、B 分别代表红光、蓝 光）和2 种光周期（8 h‧d-1，12 h‧d-1）交叉培养，测定粗肋草的形态指标、生物量、土壤和作物分析仪器开发 （soil and plant analyzer development，SPAD）值、花色素苷含量和叶片颜色参数（色相值a*、色相值b*、明度 值L*、色调角h*），研究粗肋草对红蓝光质和光周期互作的响应。结果表明：（1）12 h‧d-1 光周期更有利于粗 肋草的生物量的积累，其中LP11（R∶B=1∶3×12 h‧d-1）处理的粗肋草苗木干重、鲜重均为最高，最有利于植 物生长及生物量积累；其次是LP5（R∶B=1∶3×8 h‧d-1）处理。（2）相同光质条件下，8 h‧d-1 光周期处理的粗 肋草叶片SPAD 值比12 h‧d-1 光周期处理高，12 h‧d-1 光周期处理的粗肋草叶片花色素苷含量高于8 h‧d-1 光周期 的处理，LP11 处理叶片SPAD 值最低，花色素苷含量最高。12 h‧d-1 光周期培养的粗肋草叶片颜色参数a*、b* 值比8 h‧d-1 光周期高，h*值比8 h‧d-1 光周期低。（3）隶属函数分析结果表明，LP11 处理在促进粗肋草生长及 叶色改良方面效果最好。总之，12 h‧d-1 光周期更有利于粗肋草的生长和叶片颜色变化，其中LP11 处理为最佳 光质和光周期组合。
摘要：为探究保护区内对外来红树拉关木（Laguncularia racemosa）人工林不采取剧烈扰 动生境的皆伐措施，而通过间伐修枝处理使拉关木逐渐退出更替为乡土红树林的新途径的影 响，该研究以海南东寨港国家级自然保护区内拉关木林为研究区域，依托保护区对拉关木林 进行间伐修枝，研究拉关木林间伐修枝的调控措施对恢复乡土红树群落的生态效应。结果表 明：（1）间伐修枝后拉关木残桩萌枝的无性繁殖削弱了处理效果，但一次干预（50%强度 的间伐修枝）和两次干预（50%强度的间伐修枝之后追加一次修枝）2 种处理之间，拉关木 残桩萌枝的效果没有显著差异。（2）间伐修枝能丰富林下灌木层的乡土红树种类和促进其 生长，且两次干预比一次干预的促进作用明显，但对草本层红树幼苗自然更新无显著影响。 （3）在未间伐、间伐修枝和林缘3 种样地中人工种植乡土红树苗木，间伐修枝对红海榄 （Rhizophora stylosa）、秋茄（Kandelia obovata）幼苗的存活率有一定的促进作用；且间伐 修枝处理对红海榄的生长有接近林缘条件的效果，但效果有限。建议在50%强度间伐修枝 的基础上加大间伐强度或修枝频率，在林下适当进行乡土红树植物的人工种植，同时清除拉 关木残桩萌生的枝条，可以更有利于拉关木林向乡土红树林的转化。
摘要：植物在生长发育过程中会受到各种胁迫因子的影响，非生物胁迫是其中极其重要的 一类。类受体激酶（receptor-like kinases, RLKs）是植物中广泛存在的一类蛋白，能够快速 有效地对胁迫因子作出响应，最终引起一系列生物效应。凝集素类受体激酶（lectin receptor-like kinases, LecRLKs）是RLKs 的一个亚族，其具有细胞外凝集素结构域、跨膜结 构域和细胞内激酶结构域三个结构域。根据细胞外凝集素结构域的不同可分为L、G 和C 三 种不同类型。近年来，大量的研究表明植物凝集素类受体激酶在非生物胁迫响应中发挥重要 作用。LecRLKs 通过识别非生物胁迫相关的信号分子，激活下游的信号通路，如MAPK 通 路、ROS 通路、钙信号通路等，调节基因表达和蛋白质翻译以增强植物的抗逆性。该文概 述了植物凝集素类受体激酶的结构特征及其分类，并系统综述了LecRLKs 在盐胁迫、低温 胁迫、干旱胁迫、机械损伤和植物激素等非生物胁迫响应中的功能和作用机制，同时也对 LecRLKs 的未来研究方向作出了展望。该文不仅为深入了解植物凝集素类受体激酶参与非 生物胁迫响应的功能提供参考，还为利用LecRLKs 进行作物抗逆育种改良提供理论依据。
摘要：花青素还原酶（anthocyanidin reductase, ANR）是合成黄酮类物质的关键酶之一，为明确其编码 基因结构及干旱胁迫下的表达模式和黄酮类物质含量及二者之间的相关性，该文从中国沙棘转录组数据 中筛选获得一个ANR 基因，命名为HrANR 基因。采用生物信息学软件对基因序列及编码蛋白进行分析， 并对不同胁迫下各组织中HrANR 基因的表达量和叶中黄酮类化合物含量进行相关性分析。结果表明： （1）中国沙棘HrANR 基因ORF 为1 017 bp，编码338 个氨基酸，为稳定的亲水性蛋白，其ANR 同源蛋 白具有明显的科属特性。（2）干旱胁迫下HrANR 基因在中国沙棘根、茎、叶中均有表达，但表达趋势 不同，其中在根中的表达呈先升高后降低再升高、茎中呈持续下降、叶中呈先升高后持续降低的趋势。 （3）通过芦丁标准曲线获得不同胁迫程度下中国沙棘叶内黄酮类的含量，表明黄酮类含量先持续上升， 随后略有下降，复水后上升至最高点的变化趋势，表明干旱胁迫初期叶黄酮含量与干旱胁迫呈正相关， 在严重胁迫下黄酮含量与胁迫呈负相关。（4）HrANR 基因的叶和茎的表达量与黄酮类含量呈负相关（P 叶= -0.751 43，P 茎= -0.934），根中呈正相关（P 根=0.444）。上述结果表明中国沙棘HrANR 基因的表达及 黄酮类含量变化与其抗旱性密切相关，其结果可以为中国沙棘抗旱机制的阐明提供依据。
摘要：In the Anthropocene era, human activities have become increasingly complex and diversified. The natural ecosystems need higher ecological resilience to ensure regional sustainable development due to rapid urbanization and industrialization as well as other intensified human activities, especially in arid and semi-arid areas. In the study, we chose the economic belt on the northern slope of the Tianshan Mountains (EBNSTM) in Xinjiang Uygur Autonomous Region of China as a case study. By collecting geographic data and statistical data from 2010 and 2020, we constructed an ecological resilience assessment model based on the ecosystem habitat quality (EHQ), ecosystem landscape stability (ELS), and ecosystem service value (ESV). Further, we analyzed the temporal and spatial variation characteristics of ecological resilience in the EBNSTM from 2010 to 2020 by spatial autocorrelation analysis, and explored its responses to climate change and human activities using the geographically weighted regression (GWR) model. The results showed that the ecological resilience of the EBNSTM was at a low level and increased from 0.2732 to 0.2773 during 2010–2020. The spatial autocorrelation analysis of ecological resilience exhibited a spatial heterogeneity characteristic of "high in the western region and low in the eastern region", and the spatial clustering trend was enhanced during the study period. Desert, Gobi and rapidly urbanized areas showed low level of ecological resilience, and oasis and mountain areas exhibited high level of ecological resilience. Climate factors had an important impact on ecological resilience. Specifically, average annual temperature and annual precipitation were the key climate factors that improved ecological resilience, while average annual evapotranspiration was the main factor that blocked ecological resilience. Among the human activity factors, the distance from the main road showed a negative correlation with ecological resilience. Both night light index and PM2.5 concentration were negatively correlated with ecological resilience in the areas with better ecological conditions, whereas in the areas with poorer ecological conditions, the correlations were positive. The research findings could provide a scientific reference for protecting the ecological environment and promoting the harmony and stability of the human-land relationship in arid and semi-arid areas.
摘要：Tiger nut is a bioenergy crop planted in arid areas of northern China to supply oil and adjust the planting structure. However, in the western region of Inner Mongolia Autonomous Region, China, less water resources have resulted in a scarcity of available farmland, which has posed a huge obstacle to planting tiger nut. Cultivation of tiger nut on marginal land can effectively solve this problem. To fully unlock the production potential of tiger nut on marginal land, it is crucial for managers to have comprehensive information on the adaptive mechanism and nutrient requirement of tiger nut in different growth periods. This study aims to explore these key information from the perspective of nutrient coordination strategy of tiger nut in different growth periods and their relationship with rhizosphere soil nutrients. Three fertilization treatments including no fertilization (N:P (nitrogen:phosphorous)=0:0), traditional fertilization (N:P=15:15), and additional N fertilizer (N:P=60:15)) were implemented on marginal land in the Dengkou County. Plant and soil samples were collected in three growth periods, including stolon tillering period, tuber expanding period, and tuber mature period. Under no fertilization, there was a significant correlation between N and P contents of tiger nut roots and tubers and the same nutrients in the rhizosphere soil (P<0.05). Carbon (C), N, and P contents of roots were significantly higher than those of leaves (P<0.05), and the C:N ratio of all organs was higher than those under other treatments before tuber maturity (P<0.05). Under traditional fertilization, there was a significant impact on the P content of tiger nut tubers (P<0.05). Under additional N fertilizer, the accumulation rate of N and P was faster in stolons than in tubers (P<0.05) with lower N:P ratio in stolons during the tuber expansion period (P<0.05), but higher N:P ratio in tubers (P<0.05). The limited availability of nutrients in the rhizosphere soil prompts tiger nut to increase the C:N ratio, improving N utilization efficiency, and maintaining N:P ratio in tubers. Elevated N levels in the rhizosphere soil decrease the C:N ratio of tiger nut organs and N:P ratio in stolons, promoting rapid stolon growth and shoot production. Supplementary P is necessary during tuber expansion, while a higher proportion of N in fertilizers is crucial for the aboveground biomass production of tiger nut.
摘要：Root pullout performance of plants is an important mechanical basis for soil reinforcement by plant roots in the semi-arid areas. Studies have shown that it is affected by plant factors (species, ages, root geometry, etc.) and soil factors (soil types, soil moisture, soil bulk densities, etc.). However, the effects of loading rates on root pullout performance are not well studied. To explore the mechanical interactions under different loading rates, we conducted pullout tests on Medicago sativa L. and Hippophae rhamnoides L. roots under five loading rates, i.e., 5, 50, 100, 150, and 200 mm/min. In addition, tensile tests were conducted on the roots in diameters of 0.5–2.0 mm to compare the relationship between root tensile properties and root pullout properties. Results showed that two root failure modes, slippage and breakage, were observed during root pullout tests. All M. sativa roots were pulled out, while 72.2% of H. rhamnoides roots were broken. The maximum fracture diameter and fracture root length of H. rhamnoides were 1.22 mm and 7.44 cm under 100 mm/min loading rate, respectively. Root displacement values were 4.63% (±0.43%) and 8.91% (±0.52%) of the total root length for M. sativa and H. rhamnoides, respectively. The values of maximum pullout force were 14.6 (±0.7) and 17.7 (±1.8) N under 100 mm/min for M. sativa and H. rhamnoides, respectively. Values of the maximum pullout strength for M. sativa and H. rhamnoides were 38.38 (±5.48) MPa under 150 mm/min and 12.47 (±1.43) MPa under 100 mm/min, respectively. Root-soil friction coefficient under 100 mm/min was significantly larger than those under other loading rates for both the two species. Values of the maximum root pullout energy for M. sativa and H. rhamnoides were 87.83 (±21.55) mm•N under 100 mm/min and 173.53 (±38.53) mm•N under 200 mm/min, respectively. Root pullout force was significantly related to root diameter (P<0.01). Peak root pullout force was significantly affected by loading rates when the effect of root diameter was included (P<0.01), and vice versa. Except for the failure mode and peak pullout force, other pullout parameters, including root pullout strength, root displacement, root-soil friction coefficient, and root pullout energy were not significantly affected by loading rates (P>0.05). Root pullout strength was greater than root tensile strength for the two species. The results suggested that there was no need to deliberately control loading rate in root pullout tests in the semi-arid soil, and root pullout force and pullout strength could be better parameters for root reinforcement model compared with root tensile strength as root pullout force and pullout strength could more realistically reflect the working state of roots in the semi-arid soil.