三种扇贝种间血液生理指标比较及热胁迫对栉孔扇贝血液生理指标的影响

为了比较3种扇贝血液中的K⁺、Na⁺、Ca²⁺和Cl^-浓度，血氧(pO₂)和血二氧化碳(pCO₂)气体分压及血液酸碱度(pH)的差异情况，实验利用血气分析仪对栉孔扇贝、虾夷扇贝和海湾扇贝的血液生理指标进行测定。结果显示，扇贝的血液生理指标呈现显著的物种差异，其中栉孔扇贝血液的K+浓度[(15.74±1.47) mmol/L]、Na+浓度[(388.07±11.38)mmol/L]、Cl-浓度[(462.43±6.88) mmol/L]和p O2[(140.13±15.35) mmHg]最高。此外，栉孔扇贝和虾夷扇贝的Ca²⁺浓度和pCO₂含量较高，而海湾扇贝的pH最高。对相同月龄不同大小栉孔扇贝血液指标进行比较，发现栉孔扇贝的血液pH值与其壳高呈正相关(r=0.611)，而生理指标与壳高呈负相关。随着温度的升高，栉孔扇贝血液的Ca²⁺浓度显著增加，而pO₂显著下降，K<...     

策略Ⅰ植物铁吸收稳态调控研究进展

铁是植物生长发育所必需的微量元素。作为辅酶因子和电子传递链组分，铁参与了光合作用、呼吸作用等多种重要的生理代谢过程。铁在地壳中的含量虽然丰富，但在中性和碱性土壤中大多以Fe³⁺的形式存在，溶解度极低，限制了土壤中铁的生物有效性，导致植物生长发育易受缺铁影响，致使植物缺铁失绿已成为全世界普遍关注的问题。但在低pH和长期淹水条件下，植物会吸收累积过量的铁，产生活性氧，导致植物伤害甚至死亡。因此精确调控铁的吸收转运，保持体内铁稳态是植物生长发育的基础。本文就策略I植物铁稳态调控方面的最新研究进展做一阶段性总结，并对存在的问题和未来的发展动态提出了作者的观点。     

翅碱蓬生态化学计量内稳性对模拟氮磷沉降的响应

生物有机体元素组成内稳性是生态化学计量学核心概念之一,研究植物N、P生态化学计量内稳性及N、P分配可以明确其生态策略和适应性、竞争性。采用室内盆栽方法,研究了翅碱蓬(Suaeda heteroptera)N、P内稳性与生长对模拟N、P沉降增加的响应。结果表明,N沉降增加情况下,翅碱蓬吸收积累N表现为"绝对"的生态化学计量内稳性;P沉降增加情况下,翅碱蓬吸收积累P呈现一定的生态化学内稳性,调节系数HP为0.754,HN∶P为0.792。N沉降增加促进了翅碱蓬积累P,翅碱蓬生长可能受N限制。N、P沉降增加情况下,翅碱蓬株重、P吸收积累量与株高间均表现为异速生长。N沉降增加,翅碱蓬株重生长比株高快,P积累相对减慢。P沉降增加,翅碱蓬株高生长比株重快,P积累也相对更快。     

Soil microbial respiration is regulated by stoichiometric imbalances: Evidence from a humidity gradient case

Humidity not only affects soil microbial respiration (SMR) directly, but, indirectly by regulating the availability of soil water and nutrients. However, the patterns of direct and indirect effects of humidity on SMR over large precipitation gradients remain unclear, limiting our understanding of the effects of precipitation changes on soil C cycle. Here, we investigated the relationships among humidity, soil nutrients, and SMR by identifying stoichiometric imbalances, microbial elemental homeostasis, and microbial C use efficiency along a precipitation gradient at a continental scale. The relationship between SMR and humidity index (HI) corresponded to a Richard’s curve with an inflection point threshold value of approximately 0.7. Soil microbial respiration increased with increasing humidity in drier areas (HI < 0.7), but tended to balance above this threshold. Increasing humidity exacerbated C:P and N:P imbalances across the selected gradient. Severe N and P limitations in soil microbial communities were observed in drier areas, while soil microbes suffered from aggravated P limitation as the humidity increased in wetter areas (HI > 0.7). Soil microbial communities regulated their enzyme production to maintain a strong stoichiometric homeostasis in drier areas; enzyme production, microbial biomass, and threshold elemental ratios were non-homeostatic under P limitation in wetter areas, which further contributed to the increase in SMR. Our results identified a moisture constraint on SMR in drier areas and highlighted the importance of nutrient (especially for P) limitations induced by humidity in regulating SMR in wetter areas. Understanding the modulation of SMR via soil enzyme activity may improve the prediction of soil C budget under future global climate change.     

盐胁迫对两个高羊茅品种幼苗生长及生理特性的影响

本研究以两个高羊茅(Festuca arundinacea Schreb.)品种'钛极-2LS’(Festuca arundinacea'Titanium 2LS’)和'易凯’(Festuca arundinacea'Easycare’)幼苗为研究对象，通过盐浓度递增的方式对其进行14 d高盐处理(500 mmol·L^-1 NaCl)，测定两个高羊茅品种幼苗的形态、离子含量、光合参数以及抗氧化酶活性等指标，比较其耐盐性差异。结果表明：在盐胁迫下，两个高羊茅品种幼苗地下生物量，K⁺/Na⁺，光合、荧光参数，超氧化物歧化酶活性均显著降低(P＜0.05)，但'钛极-2LS’的降低幅度低于'易凯’；两个高羊茅品种幼苗内可溶性糖和脯氨酸含量增加，但'钛极-2LS’的增加幅度高于'易凯’；此外，盐胁迫下过氧化物酶活性在'钛极-2LS’中呈上升趋势而在'易凯’中呈下降趋势。综上，盐胁迫下'钛极-2LS’可以维持相对较高的K⁺/Na⁺和较好的光合能力，积累更多渗透调节物质来缓解盐胁迫引起的渗透胁迫、离子毒害和氧化胁迫的伤害，从而更有利于植株生长，因此'钛极-2LS’耐盐性更好。     

High Ca and P homeostasis ensure stable forage Ca:P following historical nitrogen inputs in a temperate steppe

Calcium (Ca) and phosphorus (P) are essential nutrients for plant growth, with consequences on ruminant diet and health. Their balance in forage, as indicated by Ca:P ratio, is important for the absorption and utilisation of both elements by livestock. While nitrogen (N) deposition has been globally observed, it is declining or is projected to decline due to controls on N emissions in many countries. It is an open question whether N inputs would have legacy effects on forage Ca and P nutrition in grasslands. Here, we examine the changes of Ca and P concentrations and Ca:P ratio in plants and soils in a temperate steppe for three continuous years (2016 ~ 2018) following historically 6 years N inputs (2008 ~ 2013) with a gradient ranging from 0 to 20 g N m⁻² year⁻¹. Soil extractable Ca concentrations significantly decreased with increasing N addition rates in all the 3 years, but soil available P concentrations increased and Ca:P ratio decreased only in 2016. Ca and P nutrition varied greatly amongst the four plant functional types, but they were generally conservative across the historical N addition rates, due to the high stoichiometric homeostasis. Furthermore, plant Ca and P concentrations and Ca:P ratios at the community level showed no significant variation along the N addition gradient. Our results highlighted the role of plant Ca and P homeostasis in ensuring stable Ca and P nutrition in forage following historical N inputs in temperate grasslands.     

土壤氮浓度对油松天然林新生枝叶碳氮磷化学计量及其内稳态的影响

为了解油松(Pinus tabuliformis)天然林新生枝叶碳(C)、氮(N)、磷(P)化学计量特征对土壤氮浓度改变的响应及其林龄差异，揭示不同龄级油松新生枝叶N、P元素内稳态对短期氮添加的响应。以关帝山林区孝文山林场Ⅴ～Ⅶ龄级油松天然次生林为研究对象，采用野外原位氮添加试验的方法，设置对照(N₀,0)、低氮(N₁,5 g/m²)、中氮(N₂,10 g/m²)和高氮(N₃,15 g/m²) 4个施氮水平，形成不同土壤N浓度梯度，分析不同N浓度新生枝和叶C、N、P计量指标和内稳态指数。油松枝叶C、N、P含量随土壤氮浓度的增加而显著增加，C/N和C/P减小；油松枝叶C含量、C/N和C/P随龄级增加而增加，N、P含量随龄级增加而减少；根据针叶N/P,该地区油松生长主要受N限制；新生枝和叶N、P含量及N/P与土壤指标的关系均能很好被内稳态模型模拟(p<0.1),其中新生枝P含量对土壤供氮水平变化敏感，而其他指标较稳定，新生叶的内稳态...     

黄土丘陵区春小麦水分调控下植物—土壤碳氮磷化学计量学及其稳态性特征

为探究黄土丘陵区农田生态系统土壤养分限制及其循环规律,明确水分调控下春小麦叶片及根的内稳态特征,以5个灌水量处理(W₀、W₅₀、W₁₀₀、W₁₅₀、W₂₀₀)下春小麦成熟期叶片、根和0～40 cm土层土壤为研究对象,测定不同灌水处理下春小麦植株叶片、根、土壤有机碳（OC）、全氮（TN）、全磷（TP）含量及其化学计量比,揭示春小麦叶片和根随土壤养分变化的稳态性特征。结果表明:不同灌水处理下春小麦土壤OC、TN含量均具有表聚性特征,且在0～40 cm土层含量均随灌水量增加呈现出先增加后降低的趋势,表现出W₁₅₀灌水量处理最高(1.757 g·kg^-1、0.165 g·kg^-1),而土壤TP在不同土层及灌水处理下较为稳定,适当灌水(W₁₅₀)有助于提高作物根系OC含量,过度灌水(W₂₀₀)会降低其含量;春小麦土壤、根、叶片化学计量比均值表现为:C∶N（9.56、12.92、1...     

离子注入对水稻呼吸作用及酶活性的影响

研究离子注入处理水稻干种子对萌发过程中的呼吸强度、细胞色素氧化酶活性以及酯酶、过氧化物同工酶酶谱的影响。结果表明：在一定剂量范围内,随着剂量的增加,呼吸强度有增强趋势。细胞色素氧化酶对离子注入较为敏感,剂量越大酶的钝化效应越明显;在萌发５２小时和７２小时脂酶同工酶、过氧化物酶同工酶酶谱均发生改变。