茶树根系跨膜吸收氟的生理与分子机制

茶树[Camellia sinensis(L.)O.Kuntze]是高富集氟的植物,氟在叶片中被大量累积。饮茶是人们摄取氟的重要途径,氟的过量摄入会影响人体健康。茶树主要通过根系从土壤中吸收富集氟,但是根系跨膜吸收氟的生理与分子机制尚不清楚。本文综述了茶树根系吸收氟的主动和被动途径,总结根系H+-ATPase和Ca^2+-ATPase介导氟的跨膜主动吸收过程与分子机制;剖析离子通道和Al-F络合在根系被动吸收氟过程中的作用及微观过程;分析影响根系吸收富集氟的主要因素及其调控措施。提出通过研究茶树根系氟跨膜吸收相关转运蛋白及其相关基因的克隆、表达和功能验证,以揭示跨膜吸收氟的分子机制;进而研究调控根系对氟的选择吸收,以保障茶叶质量安全和饮茶健康。     

麋鹿非繁殖期生境适宜度评价指标探讨

根据麋鹿生境分布特点,将影响麋鹿生境适宜度的因素分为非生物因子、生物因子和干扰因子,运用麋鹿的生物学、生态学研究成果,对我国麋鹿生境适宜度评价指标进行了探讨。在众多影响麋鹿生存的因子中,植被、食物、水源、外界干扰、生境类型、生态安全等被确定为影响麋鹿生境适宜的主要评价因子,制定了麋鹿生境适宜度评估模型,并赋予了相应分值,可为我国麋鹿栖息地评价提供参考。     

红外复合加热型连续式智能串烤机设计与试验

基于Android平台与ATMEGA328P嵌入式系统开发,结合温控模型及传热分析等多种技术优化研制连续型自动串烤工艺系统及设备。结合中红外与电热管复合加热及同步链输送系统,设计出能适应不同直径的自旋转插拔式串签夹持机构实现物料连续化烤制,建立烤制过程基于热量平衡原理的温度控制模型,结合自适应粒子群算法(PSO)优化神经网络PID算法实现设定参数恒温控制,利用红外热成像技术对不同功率红外烤制肉制品的传热特性、辐射穿透深度、中心截面温度分布进行分析,开发完成了Atmega328P单片机逻辑运算控制系统及Android端触屏控制界面,并对该样机工艺系统肉制品连续烤制效果进行分析。系统试验结果表明:同步链输送系统与自旋机构结合实现连续化烤制过程,自旋转插拔式串签夹持器可适应直径2～6 mm范围串签,机构夹持力应不低于0.265 N,设备运行速度1 m/min时串签旋转速度5.3 r/min,恒温控制采用PSO优化神经网络PID模型得P=0.218 1,I=0.63,D=-0.151 9,烤制温度设定为160℃时上下偏差分别为2.4与2.7℃,最大波动范围5.1℃;不同功率红外管烤制物料表面温度达到100℃左右时,2 000 W中波红外管烤制效果较好,物料辐射传热穿透层深约2 mm,内部则以热传导为主,内外温差约25℃;ATMEGA328P嵌入式控制系统动作准确,Android触屏控制界面操作响应灵敏;物料烤制时间最短为6 min,生产能力为1 200串/h,为工业连续化串烤生产提供技术参考。     

Uptake and remobilization of selenium in Brassica napus L. plants supplied with selenate or selenium‐enriched plant residues

Selenium (Se) biofortification via crops is one of the best strategies to elevate the daily Se intake in areas where soil Se levels are low. However, Se fertilizer recovery (SeFR) is low and most of the Se taken up accumulates in non‐harvested plant parts and returns to the soil with plant residues. A pot experiment with soil was undertaken to study the efficiency of inorganic Se (Na₂SeO₄) and Se‐enriched plant residues for biofortification, as well as to identify the bottlenecks in Se utilization by Brassica napus L. The soil was fertilized with Na₂SeO₄ (0 and 7 µg Se kg^?1) or with Se in stem or leaf residues (0 and 7 µg Se kg^?1). A treatment with autoclaved soil was included (0 and 7 µg kg^?1 as Na₂SeO₄) to unravel the impact of microbial activity on Se uptake. The Se‐enriched plant residues produced a lower Se uptake efficiency (SeUPE) and SeFR than did inorganic Se, and soil autoclaving enhanced Se accumulation in the plants. The time required for decomposition seems to preclude crop residues as an alternative source of Se. Furthermore, B. napus had a limited capacity to accumulate Se in seeds. The study shows that the bottlenecks in Se biofortification appear to be its low bioavailability in soil and poor loading from the silique walls to seeds. Thus, improved Se translocation to seeds would be a useful breeding goal in B. napus to increase SeFR.     

铜盐毒害对紫鸭跖草养分吸收和生长的影响

通过含有不同浓度CuSO4的Hoagland营养液培养紫鸭跖草枝条,研究了紫鸭跖草对铜的耐性和超积累以及铜胁迫下紫鸭跖草生长和营养状况.结果表明:紫鸭跖草根部铜的积累量低浓度Cu2 供应时增加幅度不大,高浓度Cu2 供应时增加幅度较大;茎部的情况与根部相似;但叶部在低浓度Cu2 供应时铜的积累量几乎没有变化,高浓度Cu2 供应时铜的积累量增幅较大.在500 μmol · L-1和1 000 μmol · L-1铜处理下,紫鸭跖草整株铜积累量分别为866 mg · kg-1(DW)和1 130 mg · kg-1(DW).紫鸭跖草对铜的吸收和转运效率与铜的供给量呈正相关性.100～250 μmol · L-1铜的供应能明显促进紫鸭跖草生长.高浓度铜促进了钾、钙的吸收而阻碍了锌的吸收及镁向地上部分的运输,尽管如此,氮、磷、钾、镁、钙的浓度均在满足常规植物正常生长的浓度范围内.铜胁迫下对根部蛋白质表达活跃,氨基酸含量增加.研究结果表明紫鸭跖草对铜有很大耐性和富集能力.     

黄土高原南瓜高糖低硝酸盐施肥模式研究

采用N、P、K3因素最优设计,在陕北黄土高原进行了南瓜氮、磷、钾用量及其肥效反应模式田间试验,研究不同施肥量对南瓜硝态氮、可溶性糖两项营养品质的影响,旨在探讨南瓜品质高糖低硝酸盐的N、P、K肥效反应模式,提出优化的施肥方案。结果表明,N肥单因素对南瓜硝态氮和可溶性糖含量影响最大,K肥单因素对南瓜硝态氮和可溶性糖含量影响不显著,N与P交互作用对南瓜高糖低硝酸盐影响显著,K肥施用量一定时,氮肥与磷肥的施用量不易过大。根据南瓜N、P、K肥效反应模式,筛选出南瓜品质硝态氮含量在200mg·kg-1以下、可溶性糖含量在7%以上的较佳施肥量为施氮95～120 kg·hm-2,施磷40～70 kg·hm-2,施钾35～80 kg·hm-2,N∶P2O5∶K2O=1∶0.42∶0.37。     

The non-recoverable phosphorus following sorption onto a Brazilian Ultisol

Phosphorus (P) immobilization in soil involves geochemical (e.g., sorption, precipitation, and diffusion) and microbiological (microbial uptake) processes. Using a Brazilian Ultisol, relative contributions of both processes to the total immobilization of applied P over 14 days were investigated. The P immobilized by microbes as interpreted by microbial suppression (achieved by mercury sterilization) was 17, 50, 54, and 56% (of the total immobilized P) on days 3, 7, 10, and 14 after fertilization, respectively. In the short-term (1 to 3 days), microbes played less of a role than did the physical effect of shaking the soil, but became the major factor by days 7 to 14. Geochemical process that might be considered short-term ageing caused only 13–16% of the total immobilization in the same time period above. Calculations supported the interpretation that measurable diffusion occurred across water films on the soil particles.     

Effects of heating and autoclaving on sorption and desorption of phosphorus in some forest soils

A number of biological and chemical processes may affect soil phosphorus availability when forest fires occur, partly as a result of heating. We describe here a laboratory experiment to study the effects of soil heating on changes in sorption and desorption of P. Autoclaving was also included as an additional treatment of moist heating under pressure. Five forest soils (two Podzols, one Arenosol, one Luvisol and one Alisol) were heated to 60°C, 120°C and 250°C or autoclaved for 30 min. They were repeatedly extracted with Bray I and analysed for inorganic and organic P fractions. The desorbed P data were fitted to an asymptotic exponential equation to obtain the desorption rate and capacity parameters. Podzol and Arenosol soils showed a quick P desorption after heating, while Luvisol and Alisol soils showed a slow desorption rate. The immediate increase in available P that occurred after heating or autoclaving originated mostly from solubilisation of microbial metabolites and soil organic components. Autoclaving decreased P sorption capacity in all soils, but the effects of heating on P sorption differed among soils. Except for one of the soils, the low P-fixing soils (Podzol and Arenosol) showed a decrease in P sorption when heated to high temperatures, whereas the high P-fixing soils (Luvisol and Alisol) showed little changes after heating. Fire intensity and soil characteristics are important factors determining short-term and long-term soil P dynamics.