不同磷水平下玉米和小麦植株亚细胞中镉的积累

Corn and wheat plants were grown in a nutrient culture solution at four levels of phosphorus (0,0.12,0.60 and 3.0mmol L^-1) and two levels of cadmium(0 and 4.0umol L^-1) in greenhouse for a 18-day period.The concentrations of phosphorus and cadmium in cell wall,cytoplasm and vacuoles of roots and leaves were examined by cell fractionation techniques.With increasing phosphorus in medium,the contents of P in cell wall,cytoplasm and vacuoles of corn and wheat roots and leaves increased.The highest content of P was observed in cell wall,next in vacuoles,and the lowest in cytoplasm.The wheat subcellular fractions in both roots and leaves hab higher concentrations of phosphorus than those of corn.Increasing phosphorus in medium significantly inhibited the intracellular Cd accumulation in both species,However,at P concentration up to 3.0mmol L^-1,the Cd content in cell wall was increased.Increasing phosphorus resulted in reduction of the subcellular Cd content in cell wall was increased.Increasing phosphorus resulted in reduction of the subcellualr Cd content in corn and wheat leaves.Compared with corn,the wheat roots had a higher Cd content in the cell wall and vacuoles and a lower in cytoplasm,while in leaf subcellular fractions the wheat cell had a higher Cd content in its vacuoles and a lower one in its cytoplasm,The results indicate that phosphorus may be involved in sequestration of Cd ionic activity in both cell wall and vaculoes by forming insoluble Cd phosphate.     

供磷水平对苗期小麦地上和地下部性状关联性的影响

【目的】磷素是植物生长发育过程中必需的大量元素之一,土壤磷水平的高低对植物地上部和地下部性状有着显著的影响。探究高、低磷水平对小麦地上和地下部性状变化以及地上和地下部性状相关性变化的影响,为研究不同磷环境对小麦生长的影响,选育适应不同磷环境的优良小麦品种提供参考。【方法】小麦品种和磷水平双因素盆栽试验在河北农业大学温室内进行,供试土壤有效磷含量为5.50 mg/kg。试验设置0和200mg/kg两个施磷水平;选用10个小麦品种。小麦分别在两个磷水平下生长35天后收获,测定小麦幼苗地上部性状（干重、相对生长速率、地上部磷吸收量、地上部磷含量和叶绿素含量）和根部性状（根干重、根长、根冠比、比根长、根直径、细根比例、根组织密度、根际土壤pH和酸性磷酸酶活性）。【结果】与高磷处理相比,低磷处理小麦地上部干重、地上部磷吸收量以及地上部磷含量分别显著降低了57.9%～72.2%、85.7%～89.8%、61.3%～71.7%,小麦根长、细根比例、根组织密度、根冠比以及比根长分别增加了50.9%～249.5%、32.5%～442.5%、–34.5%～400.0%、27.4%～198.9%、74.4%...     

磷锌施用量对苗期玉米吸收ZnCuMn的影响

在温室条件下，以石灰性褐土和玉米为试验材料，研究了汪同Ｐ，Ｚｎ施用量对玉米苗期吸收Ｚｎ，Ｃｕ和Ｍｎ的影响，结果表明，农作物对营养元素的吸收是有平衡要求的，相互促进，相互制约，满足作物对大量元素供给，是发挥微量营养元素作用的前提，而过量的微量元素，则有可能成为有害因子危害作物的正常生长发育。     

氮磷用量对小麦玉米植株吸收氮磷量的影响

根据农作物的需肥量、目标产量及土壤的供肥能力,进行测土配方施肥,是目前在大面积农业生产上广泛应用的施肥技术。     

磷水平对不同磷效率小麦叶绿素荧光参数的影响

采用溶液培养方法,研究了磷水平(0、10、100、500和1000μmol/L)对不同磷效率小麦(西农979和小偃6号)幼苗基部第1叶叶绿素荧光参数与叶绿素含量的影响。结果表明,随着磷水平的增加,两小麦幼苗基部第1叶的叶绿素a荧光参数均表现出先升高后降低的趋势,不同的是小偃6号在磷水平为100μmol/L时就达到了峰值,而西农979的最大值则出现在500μmol/L磷水平下。说明小偃6号(磷高效)的光能转换效率和电子传递效率高于西农979,且受低磷胁迫的影响较小。     

玉米自交系苗期磷营养特性评价

利用一元线性回归模型对9种基因型玉米自交系在6叶龄苗期的磷(P)营养特性进行了评价。以幼苗的全株或地上部生物量(mg/plant)分别与培养介质对其供磷量(P.mg)建立线性模型,其回归系数作为全株或地上部磷效率的指标;以幼苗的全株或地上部生物量分别与相应的全株或地上部磷含量(P.mg/plant)建立线性模型,其回归系数作为全株或地上部磷利用效率的指标;以幼苗全株磷含量与培养介质对其供磷量建立线性模型的回归系数作为幼苗磷吸收效率的指标。结果表明,9种玉米基因型的磷效率,磷利用效率和磷吸收效率的平均值分别为53.95(全株)和42.61(地上部)、131.84(全株)和124.45(地上部)、0.41。自交系04419的磷效率比平均值约高出45%(全株)和59%(地上部),属于磷效率高效型;而自交系04065和04088的磷效率分别比平均值约低43%、38%(全株)和55%、51%(地上部),属于磷效率低效型;其余自交系的磷效率介于两者之间,为磷效率中间型。玉米自交系苗期的磷效率与磷吸收效率呈显著正相关,与磷利用效率关系不明显;磷吸收效率可作为苗期磷效率预筛选的生理指标。     

新疆冬小麦品种苗期磷效率差异研究

通过室内盆栽试验,研究了 32个新疆冬小麦品种在苗期低磷和高磷水平下干物质重、叶绿素含量、类胡萝卜素含量、氮累积量和磷累积量的差异,以筛选出磷高效利用品种。结果表明:低磷和高磷处理,小麦叶绿素含量、类胡萝卜素含量、干物质重及氮磷累积量在各品种之间差异显著。聚类分析可以看出,施磷后新冬 4号和新冬 53号磷累积量增幅最大,对磷的响应比较敏感,为高磷高效品种;新冬 5号在低磷条件下磷累积量最大,为低磷高效品种,且新冬 5号叶绿素含量受磷的影响最敏感;在高磷条件下,新冬 9号、新冬 18号、新冬 19号、新冬 28号、新冬 33号、新冬 35号、新冬 49号和新冬 52号品种具有较高的磷累积量,为高磷较高效品种;高磷及低磷处理条件下,新冬 6号、新冬 12号、新冬 20号、新冬 23号、新冬 24号、新冬 26号品种磷累积量均最低,为磷低效品种。     

不同供磷水平对玉米干物质和磷动态积累及分配的影响

采用田间试验研究了不同供磷水平对玉米干物质和磷动态积累、分配规律及磷肥效率的影响。结果表明,施磷增加玉米茎、叶、穗轴、子粒和整株干重及磷含量,降低磷肥表观利用率、农学效率和生理利用率。随生长推进,不同供磷水平的子粒和整株干重及磷含量不断增加直到成熟,其余器官干重和磷积累峰值出现时间早晚不同;生长后期,子粒成为唯一的库器官,茎、叶、根,甚至穗轴均成为源,有一部分光合产物和磷输出,被重新分配到子粒。出苗后79～100 d,各供磷水平下的子粒干重净增量是相应出苗后58～79 d的0.75～1.02倍;前者子粒磷净增量是相应后者的1.56～2.39倍,说明光合产物和磷向子粒中运输不是同步的过程。同一取样时期,随施磷量增加,各器官的干重和磷含量增加,以施P2O5 90 kg/hm2最好,产量达11231.6 kg/hm2,原因是该处理的玉米穗长、行粒数和单株粒重显著增加,禿尖长度显著减少。     

小麦累积光合量的估算及其规律分析

在分析小麦（扬麦５号）生育期内环境条件与单叶光合速率变化关系的基础上，建立了用气象因子计算累积光合量的模式。用此模式可估算出小麦的某日、某一发育期及全生育期的累积光合量，由该模式计算出的结果与实测值相差很小，具有较好的拟合效果。这就使得我们仅用常规气象资料，即可估算出小麦的累积光合量。同时，还根据计算的结果分析了小麦累积光合量的变化规律，这将有助于我们对小麦干物质累积过程的进一步认识。     

小麦累积光合量估算方法探讨

分析了目前常用的计算作物累积光合合量的几种方法，并提出了一种新的方法。通过比较这几种方法的拟合精度及优缺点，对这几种方法进行了评价，以图找出精确、简单而又实用的方法。     

玉米生育期的海拔效应研究

为使高海拔地区的玉米生产布局和品种类型利用更加合理,采用作物生态学的田间试验方法,于2006～2007年间,在甘肃省和云南省各设5个试验点,研究了北、南异地不同玉米品种在不同海拔高度的生态效应.结果表明,在播期大体相同的条件下,玉米拔节期、抽雄期、成熟期随海拔的升高而相应延迟,即播种～拔节、拔节～抽雄、抽雄～成熟的"三段生长"时间相应延长.反映生育期长短的出苗～成熟天数与海拔之间呈0.01水平的正相关.本试验条件下,海拔每升降100 m,参试玉米品种的生育期延长或缩短4～5 d,株高和穗上叶数呈随海拔升高而降低趋势.     

菌根对紫色土上间作玉米生长及磷素累积的影响

丛枝菌根真菌(arbuscular mycorrhizal fungi,AMF)在土壤与植物系统的磷素循环中发挥着关键的作用。本文通过盆栽模拟试验研究了不同AMF接种状况[不接种(NM)、接种Glomus mosseae(GM)、接种G.etunicatum(GE)]和玉米/大豆间作体系不同根系分隔方式(不分隔、尼龙网分隔、塑料膜分隔)对间作玉米植株生长及磷素吸收累积的影响。研究结果表明:GM处理下的间作玉米根系侵染率在不同根系分隔方式之间的差异不显著,而GE处理则在塑料膜分隔处理下对玉米的侵染率最高。接种不同AMF对间作玉米促生效果不同,GM和GE处理在不同根系分隔情况下表现出各自的优势,与未接种处理相比,GM处理能使玉米生物量、株高有一定程度增加并在根系不分隔处理下玉米磷吸收较多、生长较好;GE处理能使植株生物量有一定程度增加并在尼龙网分隔处理下的玉米磷吸收较多、生长较好。间作体系不同根系分隔方式对玉米的影响也不同,其中玉米地上部生物量在根系分隔处理下普遍小于不分隔处理,但根系生物量的大小情况则刚好相反。另外,无论何种接种状况,玉米根系磷含量及吸收量均以尼龙网分隔处理显著较高。而根系磷吸收效率则以接种G.mosseae且不分隔根系处理显著高于分隔处理。所有复合处理中,以接种G.etunicatum与尼龙网分隔根系组合处理对间作玉米的生长及磷素累积的促进作用最好,若应用于滇池流域,可望有效控制坡耕地土壤磷素的迁移。     

不同覆膜栽培方式对玉米干物质积累及产量的影响

为探讨地膜覆盖栽培方式的增产机理,完善地膜覆盖玉米栽培技术,采用田间试验法,以露地平播为对照,比较了全膜双垄沟播、半膜双垄沟播、半膜平铺、膜侧沟播等4种栽培方式对玉米叶面积、光合势、干物质积累、穗部性状、产量及其构成因子、水分利用效率的影响,并进行了成本和效益分析。结果表明:全膜或半膜双垄沟播显著增加了各个生育时期玉米的叶面积,半膜平铺和膜侧沟播作用不大;全膜和半膜双垄沟播及膜侧沟播显著提高了玉米的光合势,半膜平铺对生长前期光合势有一定促进作用,但后期出现不利影响;全膜和半膜双垄沟播增加了玉米穗长、穗粗、穗行数和行粒数,但也增加了秃顶长。半膜平铺对穗长、穗粗和穗行数有一定促进作用,降低了秃顶长,但对行粒数作用并不明显。膜侧沟播对穗长、穗行数和行粒数有一定促进作用,但对穗粗和秃顶长作用并不明显;各种覆膜栽培方式均提高了玉米穗粒数和百粒重,但降低了单株成穗数。穗粒数与产量的灰色关联度最大、百粒重次之、单株成穗数最低;全膜双垄沟播、半膜双垄沟播、膜侧沟播、半膜平铺栽培方式分别比对照增产67.23%、60.08%、38.81%和20.02%,水分利用效率分别比对照提高66.43%、59.54%、38.35%和19.63%,经济收益分别比对照增加85.51%、69.58%、36.37%和18.69%。说明全膜双垄沟播玉米具有较高的产量和经济收益优势。     

Changes in bacterial populations along roots of wheat (Triticum aestivum L.) seedlings

Summary In this study the bacterial populations on root tips (1–2 days old) of wheat (Triticum aestivum L.) were compared with the populations on root segments about 1 week older (root base). The isolates were characterized with a set of physiological tests and the test results were used to group the bacteria by means of cluster analysis. Some clusters contained bacteria that occurred mainly on the root tips and were characterized by the ability to produce acid from different sugars and by the presence of the enzymes nitrate reductase, lipase, and oxidase; they were sensitive to high salt concentrations in the media. Another cluster included significantly more isolates from the root-base segments; these bacteria were characterized by a negative reaction to most of the physiological tests; the colonies formed by these bacteria had yellow pigmentation. Possiblemechanisms for the changes in the bacterial populations are discussed.     

铝胁迫下磷对水稻苗期生长的影响及水稻耐铝性与磷效率的关系

选用两个耐铝性差异较大的水稻品种武运粳7号(耐铝品种)和扬稻6号(铝敏感品种)作为实验材料,利用水培铝-磷交替处理试验研究了磷对水稻铝胁迫下苗期生长的影响及水稻耐铝性与磷效率之间的关系。结果表明,从水稻铝-磷交替处理下的生物量和根系形态等指标来看,P缓解了Al对两个水稻品种的毒害作用,且对敏感品种扬稻6号的缓解作用更加明显。铝-磷交替处理下,武运粳7号的体内磷含量显著高于扬稻6号的,而根部铝含量显著低于扬稻6号,因此武运粳7号体内的P/Al显著高于扬稻6号;同时,虽然两个品种间根表及根自由空间中Al浓度没有差别,而武运粳7号根表及根自由空间中P浓度显著高于扬稻6号,表现出耐铝品种更强的质外体解铝毒能力,这可能与武运粳7号较强的磷吸收效率有关。此外,与耐铝品种武运粳7号相比,铝敏感品种扬稻6号虽然磷吸收效率低,但利用效率高,即两个水稻品种的耐铝性与水稻的磷吸收效率和利用效率不一致,这为酸性土壤水稻育种提供了理论基础,即选育适应酸性土壤的水稻基因型不仅要关注其耐铝性还要关注其磷利用效率。     

Increased abundance of arbuscular mycorrhizal fungi in soil coincides with the reproductive stages of maize

Arbuscular mycorrhizal (AM) fungi are recognized for their positive effects on plant growth, playing an important role in plant P nutrition. We used C16:1cis11 and C18:1cis11 fatty acid methyl ester (FAME) biomarkers to monitor the dynamics of AM fungi during the reproductive stages of maize (Zea mays L.) grown at high yield in Nebraska, USA. Two fields with four different levels of P availability were sampled throughout the reproductive stages. Chambers, made of PVC enclosed mesh fabric to allow passage of roots and hyphae (+R) or hyphae alone (-R) and amended with either KH₂PO₄(+P) or distilled water (-P), were installed in the field at tasselling and removed after three, six and nine weeks. Our objectives were (i) to provide evidence for C allocation to AM fungi during the reproductive stages of high productivity maize and (ii) to link AM fungal growth dynamics with changes in soil P availability. We observed that initial AM FAME concentration was lower at sites with a high availability of P. During the reproductive growth of maize, AM biomarkers increased inside the chambers and were consistent with the biomarker increase observed in adjacent field soil. This confirms that there is C allocation from the plant to the symbiont during the reproductive stages of maize. We also observed a reduction in available P in +R and -R chambers. This observation implies that hyphae were as efficient as roots and hyphae in reducing the P concentration in chambers. These results demonstrate that AM fungi are active during the reproductive growth stages of maize and may benefit high productivity maize crops by facilitating P uptake.     

Establishment of a core collection for maize germplasm preserved in Chinese National Genebank using geographic distribution and characterization data

Since the 1980s, a large collection of maize has been preserved in the China National Genebank. To facilitate the evaluation and utilization of these valuable germplasm resources, a core collection was established. The collection was firstly divided into two groups, i.e. the landraces and inbred lines. The percentage of the original collection to be included in the core was given as 7% based on a previous study of sampling strategies in maize. Each group was sequentially stratified based on administrative provinces or regions and kernel types, and a clustering method was applied in further stratification. A logarithmic strategy was used to determine the number of entries in the core at each step. The process resulted in the maize core comprising 951 landraces and 242 inbred lines. Shannon-Weaver diversity index and means were used to validate the core. The core can be used effectively in further in-depth research and maize improvement.     

Morphological classification of maize landraces from northern Spain

One hundred landraces of maize from Northern Spain werecharacterized on the basis of twenty-two morphological traits,and seventeen ecological variables (climatic, edaphic andtopographic) associated with the collection site. Highbroad-sense heritabilities ( > 0.6) were foundfor plant height, ear height, ear node number, ear length,mid-ear diameter, rows of kernels, kernels per row, cob weightand days to silking. Seven different groups were obtained withcluster analysis using plant and cycle traits, and discriminantanalysis showed that leaf area, ear shape, tassel branches, rows ofkernels, plant height, cob weight, and ear length were the mostimportant traits for taxonomic classification. Seven populations withpromising breeding value were detected.     

麦茬处理方式对机播夏玉米的生态生理效应

为探求适合黄淮海平原机播夏玉米的最佳麦茬处理方式,采用大田试验,研究了麦茬处理方式(平茬、立茬、除茬)对机播夏玉米的生态生理效应.结果表明,平茬有利于提高土壤含水率、平衡和改善耕层土壤温度,较好地满足玉米生长对土壤温度和水分的需求.3展叶时,玉米叶面积、干物质重等指标都以除茬处理最好;6展叶时,平茬处理玉米的株高、单株干重、叶面积、光合速率均表现最优,产量也最高.所以平茬处理为机播夏玉米的生长提供了较好的生态条件,促进了夏玉米的生长发育和产量的提高,有很大的推广价值.     

Genetic diversity of winter wheat in Shaanxi province, China, and other common wheat germplasm pools

Cultivated Chinese wheat germplasm has been a valuable genetic resourcein international plant breeding. Landraces endemic to China are a geneticresource that is distinct from other wheat germplasm. Patterns of geneticdiversity among cultivated Chinese accessions and relationship to othergermplasm pools are unknown, despite the proven value and potential novelty. Theobjective of this work was to determine the level of genetic diversity withinimproved Chinese germplasm in the context of several other wheat germplasmpools. We analyzed a set of improved accessions cultivated from the 1940s to the1990s in Shaanxi province, China, using six simple sequence repeat (SSR) primerpairs and 30 restriction fragment length polymorphism - probe enzymecombinations (RFLP-PEC) previously used to characterize 21 geographically basedgermplasm pools. Shaanxi germplasm consists of three groups based on foreignintroductions from Italy, Australia, Denmark, and Russia. There was a decreasein genetic diversity among Shaanxi accessions cultivated in the 1970s and 1980sto the 1990s, and accession classifications based on primary decade ofcultivation were found to be significantly undifferentiated. The analysis of themean genetic distance among 22 geographically based pools of germplasm suggestsseveral regions are significantly undifferentiated. A vast majority of the totalamount of variation was found within pools; therefore, pools appear to belargely differentiated based on small differences in band relative frequency andfew if any unique bands. Previous studies have identified some Chinese landracepools as morphologically and genetically unique. The Shaanxi pool does not havethe same unique morphological or genetic features, nor is it more similar to thelandrace pools than other improved germplasm pools.