无公害蔬菜营养与施肥研究进展

本文综述了无公害蔬菜定义、卫生评价标准及生产环境评价标准。对无公害蔬菜生产中常用的氮肥在土壤中转化、种类和形态、用量和时期与硝酸盐关系,过量氮肥对蔬菜体内硝酸盐累积影响,对地下水质污染和人体健康的影响,磷肥过量引起流失造成水体富营养化和磷肥中镉对土壤生态环境污染的影响,以及畜禽粪肥、城市垃圾和污泥堆肥对蔬菜品质及环境影响进行了评述。对近二十年来土壤栽培条件下应用于无公害蔬菜营养诊断与平衡施肥研究的养分平衡法、肥料效应函数法、NPK比例法、土壤测试指数法、植物营养外观及测试指标诊断法、DRIS作物营养诊断施肥综合法,植株硝酸盐速测反射仪法等进行了综述。     

无公害蔬菜营养与施肥研究进展

本文综述了无公害蔬菜定义、卫生评价标准及生产环境评价标准。对无公害蔬菜生产中常用的氮肥在土壤中转化、种类和形态、用量和时期与硝酸盐关系,过量氮肥对蔬菜体内硝酸盐累积影响,对地下水质污染和人体健康的影响,磷肥过量引起流失造成水体富营养化和磷肥中镉对土壤生态环境污染的影响,以及畜禽粪肥、城市垃圾和污泥堆肥对蔬菜品质及环境影响进行了评述。对近二十年来土壤栽培条件下应用于无公害蔬菜营养诊断与平衡施肥研究的     

植物吸收转运无机氮的生理及分子机制

氮是植物生长必需的营养元素。植物从土壤中吸收的氮素主要是NO3-和NH4 等无机氮源。植物吸收NO3-和NH4 的系统均有高亲和转运系统(high-affinity transport system,HATS)和低亲和转运系统(low-affinity transport system,LATS)之分。近10多年的研究已对这些转运系统的分子基础有了较好的理解,本文着重对近年来植物吸收无机氮分子机制的研究进展进行了综述。     

植物吸收转运无机氮的生理及分子机制

氮是植物生长必需的营养元素。植物从土壤中吸收的氮素主要是NO3-和NH4 +等无机氮源。植物吸收NO3-和NH4+的系统均有高亲和转运系统(high-affinity transport system, HATS)和低亲和转运系统(low-affinity transport system, LATS)之分。近10多年的研究已对这些转运系统的分子基础有了较好的理解, 本文着重对近年来植物吸收无机氮分子机制的研究进展进行了综述。     

高等植物硝酸盐转运蛋白的功能及其调控机制

硝酸盐是植物从土壤中吸收的重要无机氮素形态。植物为适应含有不同浓度NO3-的土壤环境,进化出了高亲和硝酸盐转运系统(HATS)和低亲和硝酸盐转运系统(LATS),两个基因家族NRT1和NRT2家族分别参与了LATS和HATS的NO3-的吸收和转运。近年来,随着分子生物学技术和植物基因组学的快速发展,研究人员克隆出了大量参与硝酸盐吸收和转运的基因,并对这些基因的功能进行了深入研究,逐渐形成了复杂的硝酸盐调控网络。综述了植物中硝酸盐转运蛋白基因的克隆、表达及调控,并对进一步的研究作了展望,这些结果对于理解植物硝酸盐吸收的调控机制具有重要作用。     

植物钾营养高效与膜运系统的关系

HKT1和HAK1等转运子介导钾离子的高亲和吸收以及K^ /Na^ 共运转,从而可能增强Na^ 替代K^ 能力,KAT1和KST1等离子通道介导钾离子的累积和转运,从而调节气孔细胞的渗透压,控制气孔运动,阐述了植物生物膜上离子转运机制和钾营养高效机理的某种可能的关系,这些转运子和通道的高效表达可能与植物钾营养高效有很大的相关性。     

植物钾营养高效与膜转运系统的关系(英)

HKT1和HAK1等转运子介导钾离子的高亲和吸收以及K+/Na+共运转,从而可能增强Na+替代K+的能力;KAT1和KST1等离子通道介导钾离子的累积和转运,从而调节气孔细胞的渗透压,控制气孔运动。阐述了植物生物膜上离子转运机制和钾营养高效机理的某种可能的关系。这些转运子和通道的高效表达可能与植物钾营养高效有很大的相关性。     

植物对硼的吸收、转运及其遗传调控(综述)

硼是植物生长发育必需的一种微量营养元素,缺硼和硼毒害是国内外农业生产中普遍存在的问题,不仅影响产量,而且还会降低品质。近年来,植物的硼吸收和转运机制研究取得较大进展,从而为基因工程改良植物的缺硼和硼毒害奠定了重要基础。本文就植物对硼的吸收和转运机制以及植物对缺硼和硼毒害耐性的遗传调控研究概况进行综述。     

与高等植物吸收(NO_3)~-/(NH_4)~+、(PO_4)~(3-)和K~+有关的膜转运蛋白编码基因的分子生物学研究现状

高等植物对土壤中营养元素的吸收是其一切生命活动过程的基础,尤其在营养元素缺乏的状态下,更与其抗营养饥饿等特性息息相关。兼于土壤中Ｎ、Ｐ、Ｋ元素缺乏的严重性与普遍性,以及Ｎ、Ｐ、Ｋ对高等植物生长和发育的重要性,有关高等植物吸收营养元素的膜转运蛋白编码基因的分子生物学研究已引起有关学者的高度重视。ＮＯ－３／ＮＨ＋４、ＰＯ３－４与Ｋ＋膜转运蛋白均有低亲和力和高亲和力系统（ＬｏｗＡｆｉｎｉｔｙＴｒａｎｓｐｏｒｔｅｒ＆ＨｉｇｈＡｆｉｎｉｔｙＴｒａｎｓｐｏｒｔｅｒ）。对ＰＯ４３－和Ｋ＋而言,低亲和力系统是组成性表达的系统,在正常营养状态下对根系吸收营养起重要作用。而高亲和力系统是受营养缺乏而诱导表达的系统,对于植物的抗逆性、耐营养饥饿至关重要。迄今为止,与之有关的基因的全长ｃＤＮＡ或全基因已在几种植物中被克隆。此外,对基因的表达特性亦有广泛研究。本文简要概述这三大营养元素的膜转运蛋白编码基因的分子生物学研究现状。     

植物磷营养高效的分子生物学研究进展

挖掘利用植物自身的磷高效营养遗传资源是农业可持续发展的关键。磷高效营养性状涉及根形态、根分泌物、膜与体内磷转运以及菌根等许多方面,表现为数量遗传性状及受多基因控制。近年来,许多高亲和磷转运子基因已被克隆, 磷向地上部转运和磷吸收负反馈调节的控制基因也被发现, 对于根系分泌有机酸和酸性磷酸酶的基因的控制也有了一定的了解, 但目前对于根毛、排根、根构型以及菌根的营养学意义性状的分子生物学研究进展缓慢。     

Nitrate transport system in Neurospora crassa

Nitrate uptake in Neurospora crassa has been investigated under various conditions of nitrogen nutrition by measuring the rate of disappearance of nitrate from the medium and by determining mycelial nitrate accumulation. The nitrate transport system is induced by either nitrate or nitrite, but is not present in mycelia grown on ammonia or Casamino Acids. The appearance of nitrate uptake activity is prevented by cycloheximide, puromycin, or 6-methyl purine. The induced nitrate transport system displays a K_m for nitrate of 0.25 mM. Nitrate uptake is inhibited by metabolic poisons such as 2,4-dinitrophenol, cyanide, and antimycin A. Furthermore, mycelia can concentrate nitrate 50-fold. Ammonia and nitrite are non-competitive inhibitors with respect to nitrate, with K_i values of 0.13 and 0.17 mM, respectively. Ammonia does not repress the formation of the nitrate transport system. In contrast, the nitrate uptake system is repressed by Casamino Acids. All amino acids individually prevent nitrate accumulation, with the exception of methionine, glutamine, and alanine. The influence of nitrate reduction and the nitrate reductase protein on nitrate transport was investigated in wild-type Neurospora lacking a functional nitrate reductase and in nitrate non-utilizing mutants, nit-1, nit-2, and nit-3. These mycelia contain an inducible nitrate transport system which displays the same characteristics as those found in the wild-type mycelia having the functional nitrate reductase. These findings suggest that nitrate transport is not dependent upon nitrate reduction and that these two processes are separate events in the assimilation of nitrate.     

The nutrition of vegetables in sand

The yield data available from the author's series of investigations on vegetable nutrition in sand have been plotted against the concentrations of the elements concerned (nitrogen, phosphorus, and potassium), and the curves so obtained have been discussed. Within the ranges of concentrations employed, it is observed that too much available nitrogen or, especially, available phosphorus, causes depressions in yields with the tops and/or roots of certain vegetables, turnip roots being particularly susceptible to too much available phosphorus; no case of over-employment of available potassium, however, is noted. The turnip is recommended as a type plant for indicating the state of soil fertility as regards available (nitric) nitrogen.     

Nitrate transport in the cyanobacterium Anacystis nidulans

A significant progress in the knowledge of different aspects of nitrate transport in the unicellular cyanobacterium Anacystis (Synechococcus ) has been achieved in the last few years. The main contributions of our group are summarized in this article and discussed in relation to other information available. Endergonic accumulation of nitrate into the cells, indicative of the operation of an active nitrate transport system, has been experimentally substantiated and methods established to evaluate and analyze the activity of the system. Nitrate transport activity is sensitive to regulation exerted by products of both ammonium and CO₂ assimilation, thus providing evidence that photosynthetic nitrate assimilation in cyanobacteria is primarily controlled at the level of substrate supply to the cell. The expression of nitrate transport was also shown to be under nitrogen control, being repressed when ammonium is used as the nitrogen source. A 47-kDa polypeptide, which is a major plasma membrane component in nitrate-grown cells but is virtually absent in ammonium-grown cells, was identified as an essential component of the nitrate transporter. More recently, evidence of a strict Na'-dependence of active nitrate transport has been obtained, Δμ(Na⁺) appearing as the driving force of a sodium-nitrate symport system. Kinetic studies indicate also that the nitrate transporter may transport nitrite into the cell.     

重庆市蔬菜硝酸盐、亚硝酸盐含量及其与环境的关系

在重庆市的主要蔬菜中,硝酸盐含量依次为根菜类＞叶菜类＞葱蒜类＞瓜类＞豆类＞茄果类,前３类的硝酸盐含量超标,但各种蔬菜的亚硝酸盐含量一般较低,未超过卫生标准。就同一种蔬菜的不同样品而言,硝酸盐和亚硝酸盐含量的差异很大,说明品种或环境条件可显著影响其含量。重庆市多雾少光,冬春低温,土壤含氮量和钠高子含量较高,有效钾含量较低可能是导致蔬菜大量积累硝酸盐的环境因素。蔬菜不同器官硝酸盐和亚硝酸盐含量各异,根＞茎＞叶柄＞叶片。     

Nitrate Reduction and Partitioning of Nitrogen in Komatsuna (Brassica campestris L. var. rapa) Plants: Compartmental Analysis in Combination with 15N Tracer Experiments

Komatsuna (Brassica campestris L. var. rapa cv. Misugi) is aleafy vegetable that readily accumulates nitrate in its tissues.Plants grown hydroponically with 2 mM nitrate in a greenhousewere fed ¹⁵N-labeled nitrate for 2 h, followed with nonlabelednitrate for 8 h. At intervals of 2 h, the plants were sampledand analyzed for the distribution of 15N in the nitrate, aminoacids, and proteins in the tissues of roots, petioles plus midribs,and leaves. Nitrate reduction and nitrogen fluxes were examinedusing a compartmental analysis with 19 compartments and 28 transferrate constants. Nitrate existed in the three types of tissues as a large storagepool and a small metabolic pool. Nitrogen reduction was observedin these tissues, but mainly in the leaf tissue. Nitrate uptakeand reduction rates were smaller in the dark than in light,and particularly nitrate reduction in the shoot was less inthe dark. The rate of protein synthesis was much greater inthe light. The simulation, using compartment models and ¹⁵Ndistribution data, may be useful for estimating actual ratesof nitrogen transport and metabolism in the whole plant system. (Received October 15, 1986; Accepted March 26, 1987)     

The Effect of Inhibitors of Photosynthetic and Respiratory Electron Transport on Nitrate Reduction and Nitrite Accumulation in Excised Z. mays L. Leaves

The assimilation of nitrate and nitrite under dark and lightconditions in Zea mays L. leaves was investigated. Nitrate wasassimilated under dark-aerobic conditions. Anaerobiosis stimulatednitrate reduction and nitrite accumulation under dark conditions.Vacuum infiltration of inhibitors of respiratory electron transport,antimycin A and rotenone, stimulated nitrate reduction and nitriteaccumulation under dark-aerobic conditions. Vacuum infiltrationof low concentrations of PCP, DNP and mCCCP depressed nitratereduction and nitrite accumulation under dark-aerobic conditions,whereas, infiltration of higher concentrations stimulated nitratereduction and nitrite accumulation. The greatest level of nitrateand nitrite reduction occurred under light conditions. The inhibitorof photosynthetic electron transport, DCMU, stimulated the accumulationof nitrite in the light, but decreased nitrate reduction. Whenthe inhibitors of respiratory electron transport antimycin Aand rotenone, were supplied together with DCMU in the light,nitrite accumulation was enhanced. Low concentrations of mCCCPdecreased both nitrate reduction and nitrite accumulation underlight conditions when supplied with DCMU. Key words: Nitrate reduction, Nitrite accumulation, Leaves     

菜地土壤氮磷面源污染现状、机制及控制技术

为了提高蔬菜产量,菜农大量施用化肥,菜地氮磷肥用量在一些地区已超过蔬菜实际需求量的数倍;而大多数蔬菜是浅根系和没有庞大根系的作物,菜地土壤已出现明显的氮磷累积现象,从而导致蔬菜作物营养失调,硝酸盐含量严重超标、品质下降,并引起菜地土壤理化性状恶化、地下水硝酸盐污染及地表水富营养化等一系列环境问题.本文综述了菜地土壤氮磷面源污染现状(氮磷累积特征、对水环境及蔬菜污染现状)、污染机制(氮磷来源、转化特征及损失途径)及包括施肥控制技术、应用化学添加剂技术、填闲作物技术、种植制度优化技术、汇源景观组合和生态草带拦截技术等污染控制技术,旨在为菜地土壤氮磷面源污染的深入研究提供借鉴.