不同磷效率小麦品种对缺磷胁迫反应的比较

在营养液培养条件下,以根据相对产量为指标筛选出的6个不同磷效率的小麦(Triticum aestivum L.)品种为材料,对其苗期在缺磷条件下生长、根冠磷含量及其分配,以及叶片韧皮部汁液中磷浓度等进行了比较研究.结果表明,缺磷抑制植株地上部生长,但刺激根系生长,导致植株根/冠比增加.无论在供磷或缺磷条件下,磷高效品种的根冠生长速率都低于磷低效品种.缺磷导致植株体内的磷含量下降与根系相比,地上部磷含量的下降速率更快.但在缺磷条件下,不同磷效率的小麦品种根冠间的磷分配变化没有差异.研究发现,在正常供磷条件下,磷高效小麦品种的叶片韧皮部汁液中磷浓度较低,而磷低效品种的叶片韧皮部汁液中磷浓度较高.但开始缺磷后,磷高效品种的叶片韧皮部汁液中的磷浓度下降较慢,使其相对磷浓度较高.缺磷后1 0天,磷低效品种叶片韧皮部汁液中的磷浓度为供磷对照的35.9%,而磷高效品种叶片韧皮部汁液中的磷浓度为供磷对照的59%.     

不同磷效率小麦品种的磷吸收特性

在丰磷、缺磷条件下,对不同磷效率小麦品种的磷吸收特性进行研究。缺磷条件下,不同磷效率品种成熟期的植株全磷量和生育中后期（挑旗-成熟期）植株磷累积量均以磷高效品种最高,中效品种次之,低效品种最低。不同磷效率品种拔节期、挑旗期和成熟期的磷利用效率差异较小。表明磷高效小麦品种在缺磷条件下子粒产量形成能力的提高。与生育中后期植株具有相对较强的磷素吸收能力有关。缺磷条件下,不同磷效率品种在生育中后期的根系TTC还原力和可溶蛋白含量也以高效品种最高,中效次之,低效最低。表明磷高效小麦品种植株生育中后期根系具有较强的生理功能,是其在缺磷务件下吸磷量增加、产量相对明显提高的重要生理基础。研究表明,不同磷效率小麦品种在磷胁迫条件下的根系酸性磷酸化酶（APase）活性存在显著差异,并在小麦磷吸收效率的调控中具有重要作用。     

缺磷条件下不同水稻品种磷素吸收特性的研究

缺磷条件下,供试粳稻品种植株的单株鲜重、干重、全磷含量和单株磷累积量等具有较大差异,从中筛选出磷高效品种TP309和优质8号,其中TP309较磷低效品种早88-1的全磷含量和单株磷累积量分别增加37.50%~40.00%和82.76%~102.00%。单株根数、平均根长和根系体积与单株磷素吸收量的相关程度较小,光合速率(Pn)、叶片可溶蛋白含量和叶片可溶性糖含量均表现为随着吸磷量的增加而不断增大。     

渗透胁迫和缺磷对小麦幼苗生长的影响

水培条件下缺磷小麦幼苗的叶片含水量和叶绿素含量显著降低,丙二醛含量增加,小麦幼苗生长受抑,地上部分生长受到的影响大于根系,上述指标的变化幅度还与缺磷程度呈正相关,且不耐低磷品种中国春大于耐低磷品种烟中144。在相同条件下,渗透胁迫和缺磷两者表现出胁迫加剧的现象。     

不同大豆品种磷吸收利用特性比较研究

土壤缺磷和低磷利用率是现代农业生产发展的主要限制因素之一,筛选和培育磷商效吸收利用品种是提高磷素利用率的有效途径。采用土壤盆栽试验方法进行了不同大豆（Glycine max（L.）Merr．）品种磷吸收利用特性比较研究。结果表明。在缺磷和正常供磷条件下,不同大豆品种植株在株离、根干重、地上部干重、根冠比率、植株磷含量和其相对值、磷吸收量和其相对值、磷利用效率和其相对比值等方面表现出显著的差异。多数达到了极显著水平。相关分析表明,在缺磷条件下,大豆不同品种植株磷的利用效率及其相对比值与植株磷含量和磷吸收量以及它们的相对值呈显著或极显著负相关。植株磷含量与植株磷吸收量呈极显著正相关。以植株干物质量和其相对值、植株磷吸收量和其相对似以及植株磷利用效率为筛选指标,筛选出3个大豆磷高效品种。     

CO2倍增对不同氮水平下小麦幼苗根系及叶片NR活性的影响

以小麦品种'小偃22'幼苗为材料,采用开顶式气室和水培实验研究了不同供氮水平(2.5、5.0、10.0和 15.0 mmol·L-1)下小麦幼苗植株生长量、根系形态、有机碳分泌速率和硝酸还原酶(NR)活性对大气CO2浓度升高的响应.结果显示,大气CO2浓度倍增均增加了小麦幼苗各生长阶段根冠生物量以及根系长度、面积、有机碳分泌速率和叶片NR活性.随供氮水平的提高,各生长阶段幼苗根冠生物量、根长和面积以及叶片NR活性呈上升趋势,而有机碳分泌速率呈下降趋势;根冠比变化不同阶段表现不一致,一叶一心期呈下降趋势,二叶一心期和三叶一心期分别以15.0和10.0 mmol·L-1氮水平较高.研究表明,大气CO2浓度升高可促进小麦幼苗根系生长和有机碳分泌速率,提高其氮素同化能力;增加介质供氮有利于高CO2浓度条件下小麦幼苗根冠生长和氮素同化,提高根冠比,减少根系有机碳过度分泌引起的碳损耗.     

磷有效性对大豆根冠中碳分配的影响

在水培条件下,研究不同浓度磷影响大豆根冠中碳分配的结果表明：磷有效性对大豆根冠中碳分配的影响依赖于磷浓度与胁迫时间。磷浓度高于0．125mmol．L^-1或低磷胁迫7d以内,大豆根冠中碳分配受到的影响不显著。低磷胁迫14d的大豆的净光合速率和根呼吸速率均显著下降,根冠比显著提高。这显示长期低磷胁迫下大豆碳同化总量和根呼吸消耗的碳量虽然减少,但根系生长的碳消耗则增加,光合碳同化形成的碳水化合物向根部的分配是受到促进的。     

缺磷胁迫下的小麦根系形态特征研究

研究了缺磷条件下不同基因型小麦（Triticum aestivum L.)苗期根系形态学适应特征,以明确环境因子对根系不同组分（根轴和侧根）生长发育调控作用的强度和根系形态与磷营养效率关系。在缺P环境中,小麦根轴数量和侧根长度明显减小,同化物向根部的分配比例增加,根轴长度、侧根数量和根系长度等均有显著提高。供试基因型小麦的根轴数量及其长度的差异在每个供磷水平及不同供磷水平之间均呈显著,说明这两种性状的差异是由基因型和环境因素共同决定的;而侧根特征的差异只在不同供磷水平间显著,表明侧根性状主要受环境因素的控制。对6种基因型小麦的研究表明,根轴数量、根轴长度、根生长角度和根系长度根角之间存在着显著的基因型差异。相关分析表明,小麦的相对产量与缺磷条件下的小麦苗期根系形态指标的交互作用之间具有显著的线性关系。这种关系说明根系形态性状可作为早期有效地筛选磷高效小麦品种的指标。     

小麦不同品种磷效率比较和评价的生化指标研究

对河北省的30个小麦品种的磷效率特征和评价的生化指标进行了研究。结果表明,供试品种在缺磷（-P）条件下的单株干重具有显著差异,供试品种-P下的磷效率可划分为高效、较高效、中效和低效等4种类型。-P处理下,单株干重和单株磷累积量随着供试品种磷效率的增大呈增加趋势;随着磷效率增大,超氧化物歧化酶（SOD）活性和过氧化氢酶（CAT）活性逐渐增加,丙二醛（MDA）含量则逐渐降低。相关分析和回归分析表明,单株干重和单株磷累积量分别与SOD活性和CAT活性呈极显著和显著正相关,与MDA含量呈极显著负相关,表明SOD活性和MDA含量可作为缺磷奈件下评价小麦品种磷效率的生化评价指标。     

小麦根系生长对缺磷胁迫的反应

研究了缺磷诱导小麦（Ｔｒｉｔｉｃｕｍ ａｅｓｔｉｖｕｍＬ．）根系生长的反应,小麦根轴的生长与植株内外的磷浓度均呈显著的负线性关系。分根实验证明,随着低磷营养液中根比例的增加,在供磷水平不同的分根盒侧的根轴长度的均增加,这说明根轴生长是受体内磷浓度调控的。植株体内磷浓度的处理后１ｄ开始变化,而在不同供磷水平营养液中小麦根轴长度的差异达到显著水平的时间是处理后的第８天,说明植株体内磷浓度的变化可能是小     

The morphological changes of wheat genotypes as affected by the levels of localized phosphate supply

Effects of localized phosphate supply on the seedling growth of wheat (Triticum aestivum L.) genotypes 81(85)5-3-3-3 (P-efficient) and NC37 (P-inefficient) were studied using a device which allowed only 3 cm length of root segment to be exposed to phosphate treatment. Localized supply of 0 mmol P L^–1 and the rest of root supplied with 0.1 mmol P L^–1 (HLH), increased the shoot height, leaf area, root/shoot ratio for 81(85)5-3-3-3, length of root and root axis for NC37, and root axis length and density of first-laterals for both the genotypes, compared to plants with the whole root system in P-sufficient solution (HHH). This suggested that above- and below-ground morphological parameters of wheat were promoted by a localized P-deficiency, presumably via a P deficiency signal. There was a significant difference in the number of first-order laterals between the two wheat genotypes when most of the roots were grown without P and only 3 cm length of root was supplied with 0.3 mmol P L^–1. The relationship between the number and density of 2nd-order lateral roots and level of local P supply was quadratic. Maximum number and density of 2nd-order lateral roots were obtained with a localized P supply of 0.70 mmol L^–1.     

Genotypic difference of potato in carbon budgeting as a mechanism of phosphorus utilization efficiency

Observed genotypic difference in P utilization efficiency in soil grown potatoes led to the present study to investigate possible mechanisms of P utilization efficiency in potato genotypes grown in nutrient solution under three P regimes (low, medium and high). For all genotypes relative growth rate (RGR), leaf P content, net assimilation rate (NAR) and leaf area ratio (LAR) increased while P utilization efficiency and leaf starch content decreased at the two higher P regimes compared to the low P regime. The P-efficient genotypes CGN 17903 and CIP 384321.3 had higher RGR compared to the P-inefficient genotypes CGN 22367 and CGN 18233, which resulted from enhanced NAR rather than from LAR. Net photosynthetic rate was similar for all genotypes. However, for P-inefficient genotype CGN 22367, the lower NAR could be explained by increased leaf dark respiration. For P-inefficient genotype CGN 18233 we speculate that increased carbon cost of root respiration or exudation or both, caused low NAR, since leaf dark respiration of this genotype was similar to that of P-efficient genotypes.     

Phosphorus and aluminum interactions in soybean in relation to aluminum tolerance. Exudation of specific organic acids from different regions of the intact root system

Aluminum (Al) toxicity and phosphorus (P) deficiency often coexist in acid soils that severely limit crop growth and production, including soybean (Glycine max). Understanding the physiological mechanisms relating to plant Al and P interactions should help facilitate the development of more Al-tolerant and/or P-efficient crops. In this study, both homogeneous and heterogeneous nutrient solution experiments were conducted to study the effects of Al and P interactions on soybean root growth and root organic acid exudation. In the homogenous solution experiments with a uniform Al and P distribution in the bulk solution, P addition significantly increased Al tolerance in four soybean genotypes differing in P efficiency. The two P-efficient genotypes appeared to be more Al tolerant than the two P-inefficient genotypes under these high-P conditions. Analysis of root exudates indicated Al toxicity induced citrate exudation, P deficiency triggered oxalate exudation, and malate release was induced by both treatments. To more closely mimic low-P acid soils where P deficiency and Al toxicity are often much greater in the lower soil horizons, a divided root chamber/nutrient solution approach was employed to impose elevated P conditions in the simulated upper soil horizon, and Al toxicity/P deficiency in the lower horizon. Under these conditions, we found that the two P-efficient genotypes were more Al tolerant during the early stages of the experiment than the P-inefficient lines. Although the same three organic acids were exuded by roots in the divided chamber experiments, their exudation patterns were different from those in the homogeneous solution system. The two P-efficient genotypes secreted more malate from the taproot tip, suggesting that improved P nutrition may enhance exudation of organic acids in the root regions dealing with the greatest Al toxicity, thus enhancing Al tolerance. These findings demonstrate that P efficiency may play a role in Al tolerance in soybean. Phosphorus-efficient genotypes may be able to enhance Al tolerance not only through direct Al-P interactions but also through indirect interactions associated with stimulated exudation of different Al-chelating organic acids in specific roots and root regions.     

低磷和干旱胁迫对大豆植株干物质积累及磷效率的影响

土壤缺磷和季节性干旱已经成为南方酸性红壤地区大豆生产的主要限制因素之一。选取2个大豆品种巴西10号(磷高效)和本地2号(磷低效),研究其在不同磷素(0,15, 30 mg/kg P)和水分处理(分别在开花期和结荚期进行干旱胁迫)下的反应,从植株生物量、叶绿素含量、磷效率指标等方面研究不同基因型大豆对水磷耦合胁迫的适应机制。研究结果表明,随着土壤磷素水平的增加,两个品种的生物量和叶片叶绿素含量显著增加,根冠比则显著下降。在同一磷素水平处理下,干旱胁迫则导致较高的根冠比,对叶片叶绿素含量影响不大,两个品种表现一致。两个基因型大豆受到干旱胁迫后,其产量均显著低于正常水分处理。中等施磷能显著提高两个大豆品种的产量,但高磷处理对产量的增加幅度有限,甚至高磷处理还造成本地2号减产。巴西10号的产量随土壤中磷素的增加而增加,而本地2号的产量则为中磷>高磷>低磷,不管是磷处理还是水分处理,巴西10号的产量均高于本地2号。无论是花期干旱还是结荚期干旱,巴西10号和本地2号的根磷效率比、磷吸收效率及磷转移效率均随土壤磷浓度的增加而增加,磷利用效率则降低。总体上来讲,巴西10号的磷吸收效率和利用效率高于本地2号,而根磷效率比、磷转移效率则小于本地2号。     

低磷胁迫下大麦叶片磷素利用特征

以大麦(Hordeum vulgare)磷高效基因型(DH110和DH147)和低效基因型(DH49)为材料, 采用盆栽实验研究大麦在极低磷(25 mg·kg^-1土)、低磷(50 mg·kg^-1土)和正常磷(75 mg·kg^-1土)处理下叶片的磷组分和酸性磷酸酶活性特征。结果表明, 低磷胁迫显著降低大麦叶片的无机磷含量, 但对难溶态磷含量影响较小。高效基因型上部叶核酸态磷含量显著高于低效基因型, 而下部叶则显著低于低效基因型, 是低效基因型的18.4%-91.4%。大麦下部叶酯磷含量和分配比例表现为高效基因型低于低效基因型, 而上部叶仅在低效基因型中显著低于高效基因型。核酸态磷和酯磷在高效基因型叶片中的含量分配表明其上部叶的磷素营养状况较优, 而下部叶易溶性有机磷的分解转化作用更强。低磷和极低磷胁迫下, 下部叶酸性磷酸酶的活性显著增加, 且高效基因型显著高于低效基因型, 分别为低效基因型的1.29-1.41倍。磷高效基因型大麦通过提高下部叶酸性磷酸酶活性加强酯磷和核酸态磷的分解, 转化为无机磷, 增加可移动性磷源的含量和比例, 以提高生育后期大麦的磷素再利用能力。     

Analysis of the contribution of acid phosphatase to P efficiency in <Emphasis Type="Italic">Brassica napus</Emphasis> under low phosphorus conditions

To understand whether genotypic variation in acid phosphatase (APase) activity in rapeseed (Brassica napus L.) induced by phosphorus (P) deficiency has impact on P efficiency, soil APase activity in the rhizosphere for rapeseed P-efficient genotype 102 and P-inefficient genotype 105 was measured against organic and inorganic P sources in the pot experiment, and the activities of root-secreted APase and leaf intracellular APase were investigated in different P-starvation periods in the nutrient solution. Higher activity of root-secreted APase in B. napus was induced under low P conditions. However, P nutrition and P uptake efficiency of the plants supplied with organic P were not directly related to the activity of root-secreted APase due to several confounding factors affecting APase availability. The higher activity of leaf APase improved P remobilization in plants and played important roles in enhancing P use efficiency, shown by the significant correlation between leaf APase activity and P use efficiency in a rapeseed recombinant inbred population of 135 lines.     

Effects of P deficiency on the uptake, flows and utilization of C, N and H2O within intact plants of Ricinus communis L.

The influence of P deficiency on the uptake, flow and utilizationof C, N and H₂0 by intact NO₃-fed castor bean plants {Ricinuscommunis L.) was studied over a 9 d period in the middle oftheir vegetative growth. The modelling techniques incorporateddata on net increments or losses of C, N and H₂O in plant parts,photosynthetic gains in and respiratory losses of C, molar C:Nratios of solutes in phloem and xylem sap and transpirationallosses of H₂0. Plant growth was inhibited within 3 d of withholdingP supply and dry matter production was less than one-third ofthe controls. Leaf growth was particularly depressed, whileroot growth was much less affected than that of the shoot. Shoot:rootratio of low-P plants was 1.5 compared with 2.6 under P supply.Over the 9 d study period total plant C and N increased by 560and 47 mmol, respectively, in the controls, but by only 113and 6.9 mmol in the low-P treatment. The particularly low incrementof N in P-deficient plants was due principally to decreasedN0₃^- uptake. Flows of C and N during the study period were markedlydifferent between control and P-deficient plants. The partitioningprofile for C in P-deficient plants showed a dramatic inhibitionof net photosynthesis and attendant photoassimilate flow. Proportionaldownward to upward allocation of carbon increased with increasein sink size of the root relative to shoot. This was reflectedin greater relative allocation of C to root dry matter and rootrespiration than in P-sufficient plants, and suppressed cyclingof C from root to shoot via xylem. Nitrogen intake and xylemtransport to the shoot of P-deficient plants were only 15% ofthe control and, as in the case of C, downward allocation ofN predominated over upward phloem translocation. Apart fromthese severe changes, however, the basic patterns of N flowsincluding xylem-to-phloem and xylem-to-xylem transfer of N werenot changed, a feature highlighting the vital nature of thesetransfer processes even under deficiency conditions. The alterationsin flows and partitioning of C, N and H₂O in response to low-Pconditions are discussed in relation to the corresponding effectsof moderate salt stress in Ricinus and the conclusion is reachedthat changes in nutrient flows under P deficiency were morehighly co-ordinated than when plants experience salt stress.Flow profiles under P deficiency which favour root growth andactivity are viewed as a means for increasing the potentialcapability of the plant to acquire P from the nutrient medium. Key words: Ricinus communis L., P deficiency, carbon, nitrogen, water, partitioning, xylem transport, phloem transport     

铁胁迫下大豆光合和磷/铁性状对磷素的响应

为了明确低铁胁迫下磷素用量对大豆光合和磷/铁性状的影响及基因型差异,为磷、铁肥的合理施用提供理论依据,以前期筛选的6个磷高效基因型和6个磷低效基因型大豆为供试材料,设4个P∶Fe配比处理,分别为0∶30、30∶30、150∶30和300∶30(μmol·L^-1),对大豆叶绿素荧光特性和磷、铁利用率进行了测定,利用单株粒重建立逐步回归方程并进行通径分析,通过因子得分综合评价磷高效和磷低效基因型对不同P∶Fe处理的响应。结果表明: 基因型效应、P∶Fe处理效应和两者互作效应对始花期(R1)光系统Ⅱ的相对电子传递速率(ETR)、光系统Ⅱ吸收的能量用于耗散为热量的比例(NPQ)、光系统Ⅱ吸收的能量用于进行光化学反应的比例(qL)的影响均达显著水平。典型相关分析表明,磷高效大豆基因型完熟期(R8)籽粒磷利用率与R1期光合速率呈负相关;磷低效大豆基因型R8期籽粒铁利用率与R1期NPQ呈正相关关系,而与R1期qL呈负相关关系;R1期PSⅡ实际光化学效率(Φ_PSⅡ)与磷高效基因型呈负相关,而与磷低效基因型呈正相关,这表明R1期Φ_PSⅡ可以作为鉴定低铁条件下不同磷效率大豆基因型的一个重要指标。利用因子得分综合评价发现,磷高效基因型表现为随着磷水平的上升而先降后升,而磷低效基因型则为先升后降,但两者拐点均出现在P∶Fe为30∶30处理下,这表明在低铁条件下P∶Fe为30∶30可以作为鉴定不同磷效率基因型的一个临界值。因而,在低铁地区种植磷高效大豆基因型时,磷肥的施用量至少要大于1∶1 (P∶Fe);而种植磷低效基因型时,磷肥的施用量不宜超过1∶1 (P∶Fe)。     

Changes in phloem export of sucrose in leaves in response to phosphorus, potassium and magnesium deficiency in bean plants

The effect of varied phosphorus (10 and 250 mmol P m^–3potassium (50 and 2010 mmol K m^–3) and magnesium (20 and1000 mmol Mg m^–3 supply on sucrose, reducing sugars, aminoacids, P, K, and Mg in phloem exudate was studied in bean (Phaseolusvulgaris L.) plants over a 12 d growth period in nutrient solution.Phloem exudates were collected from detached primary leavesusing the EDTA-promoted exudation technique. Compared with controlnutrient-sufficient plants, sucrose export in the phloem exudatewas drastically decreased by K deficiency and, particularly,by Mg deficiency, whereas P deficiency either had no effector stimulated sucrose export. In Mg-deficient plants the rateof sucrose export was decreased to 10–20% of the controlplants. There was a close Inverse relationship between phloemexport and leaf concentration of sucrose: higher leaf concentrationsof sucrose were accompanied by lower phloem export of sucrose.In contrast to sucrose, reducing sugars in the exudates werevery low and not affected by P, K and Mg deficiency. The phloemexport of amino acids was strongly depressed by Mg deficiency,but only slightly by P and K deficiency. Resupplying Mg to Mg-deficientplants for 12 h during the dark or light periods rapidly stimulatedsucrose export. After resup ply of Mg for 24 h and 48 h therate of sucrose export was comparable with the rate in the controlplants. The results demonstrate a key role for Mg in phloem loadingand export of photosynthates from source leaves, especiallysucrose. Inhibition of root growth and development of visualsymptoms of chlorosis in Mg-deficient plants are suggested asconsequences of Impaired phloem loading. In agreement with thisin P-deficient plants where phloem loading was not impaired,chlorosis was absent and root growth was maintained at a highlevel. Key words: Bean, carbon partitioning, magnesium nutrition, phloem transport, phosphorus nutrition, potassium nutrition