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。     

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。     

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10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％。     

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。     

大豆种子储藏性磷对幼苗适应低磷胁迫的作用

选用种子大小不同、磷效率不同的两个大豆品种‘巴西10号’(B10)和‘本地2号’(L2),在不同供磷条件下进行营养液浇灌沙培,从大豆萌发至2片三出复叶完全展开期测定植株主要器官总磷、可溶性磷浓度、子叶可溶性蛋白、酸性磷酸酶比活性、植酸酶比活性的变化动态,探讨储藏性磷在大豆幼苗期适应磷胁迫中的作用。结果发现:(1)磷效率不同的两个大豆品种的种子中磷含量差异显著。(2)大豆萌发和幼苗生长过程中子叶的磷逐渐转入根、茎、叶中,并以转入叶中的磷最多,其中磷高效品种B10在发芽过程中子叶磷向各个器官转移的总磷量要高于磷低效品种L2,且持续时间长。(3)大豆萌发和幼苗生长过程中外源供磷水平显著影响子叶磷的转移,在外源供磷充足条件下各器官中总磷均高于低供磷条件,子叶中磷和外源磷存在补偿关系。(4)磷高效品种B10子叶中酸性磷酸酶活性在低磷条件下显著高于高磷条件,但磷低效品种L2在高、低磷间无显著差异。研究表明,大豆种子储藏性磷在幼苗期耐低磷能力建立方面具有重要作用。     

不同小麦品种氮效率和产量性状的研究

对29个冬小麦品种进行子粒产量和氮效率的研究,结果表明,在氮胁迫条件下,供试小麦品种的子粒产量具有明显差异。缺氮条件下子粒产量的聚类分析结果表明,供试品种可划分为氮高效、中效和低效三类,氮高效品种在其中所占比例较少。在缺氮条件（N-）下,不同氮效率品种成熟期植株全氮含量差异不大,植株氮素积累量、氮效率（NUE）、吸收效率（UPE）和利用效率（UTE）均以氮高效品种最高,中效品种次之,低效品种最低。缺氮条件下较强的氮索吸收和利用能力是氮高效小麦品种氮胁迫条件下高氮效率的主要原因。     

不同磷源对磷高效利用野生大麦根际土壤磷组分的影响

在土培盆栽条件下,以野生大麦磷高效利用基因型IS-22-30、IS-22-25和低效基因型IS-07-07为材料,研究不施磷(CK)、无机磷(KH₂PO₄,Pi)、有机磷(phytate,Po)及二者混合(KH₂PO₄+phytate,Pi+Po)的方式施磷30 mg·kg^-1时,磷高效基因型野生大麦对磷素吸收利用能力及土壤磷组分特征.结果表明： Pi处理野生大麦干物质量和磷素积累量最大,Pi+Po处理其次,Po处理最小,均显著高于CK处理,且磷高效基因型物质生产和磷素吸收能力显著高于磷低效基因型.土壤有效磷在不同磷源处理间差异显著,Pi处理时含量最高,Pi+Po处理次之,且磷高效基因型野生大麦根际有效磷含量显著高于磷低效基因型.磷高效基因型野生大麦根际有效磷呈现亏缺现象,在Pi和Pi+Po处理时亏缺程度较大.根际与非根际土壤无机磷组分含量为Ca₁₀-P>O-P>Fe-P>Al-P>Ca₂-P>Ca₈-P,且其含量随着Pi的增加而增加.各磷源处理下,磷高效基因型野生大麦根际土壤Ca₂-P、Ca₈-P出现亏缺;Pi处理磷高效基因型野生大麦根际土壤Al-P、Fe-P出现富集.土壤中有机磷各组分含量为中活性有机磷>中稳性有机磷、高稳性有机磷>活性有机磷.野生大麦根际土壤活性有机磷和中活性有机磷呈现富集,其富集量在Pi处理时最大;中稳性有机磷和高稳性有机磷呈现亏缺.各磷源处理下,磷高效基因型野生大麦根际土壤活性有机磷含量显著高于磷低效基因型,中稳性有机磷和高稳性有机磷在基因型间差异不显著.Pi缺乏时,磷高效基因型野生大麦活化吸收Ca₂-P、Ca₈-P、Al-P和活性有机磷的能力较强.     

磷高效利用野生大麦基因型筛选及其根际土壤无机磷组分特征

通过土培盆栽试验,研究了16份野生大麦种质资源在相同供磷水平下磷素吸收利用的基因型差异,探讨磷高效野生大麦根际土壤无机磷组分特征.结果表明：拔节期和扬花期磷素干物质生产效率（CV=11.6%、12.4%）、成熟期磷素籽粒生产效率（CV=13.7%）基因型间差异较大.不同生育时期磷高效基因型IS-22-30和IS-22-25生物量、磷积累量和磷素干物质生产效率均显著高于低效基因型IS-07-07,且高效基因型的籽粒产量分别是低效基因型的3.10和3.20倍.不施磷、施磷30 mg·kg^-1条件下,不同磷素利用效率野生大麦根际土壤有效磷和水溶性磷含量均显著低于非根际土壤,且高效基因型较低效基因型根际土壤水溶性磷亏缺量更大.根际与非根际土壤无机磷组分含量为Ca₁₀-P＞O-P＞Fe-P＞Al-P＞Ca₂-P＞Ca₈-P.在拔节期和扬花期,施磷30 mg·kg^-1条件下,磷高效基因型根际土壤Ca₈-P含量显著高于低效基因型,而Ca₂-P含量显著低于低效基因型;不施磷条件下,高效基因型根际土壤Ca₂-P和Ca₈-P含量均显著高于低效基因型,且根际土壤Ca₁₀-P均减少.施磷30 mg·kg^-1条件下,根际土壤Fe-P和O-P含量均表现为高效基因型显著高于低效基因型,Al-P含量则呈现相反的趋势;不施磷条件下,高效基因型根际土壤Al-P、Fe-P和O-P含量均显著低于低效基因型.低磷胁迫下,高效基因型活化吸收Ca₂-P、Al-P的能力强于低效基因型.     

大气NH3升高对不同供氮水平下小麦叶片光合生理特征的影响

以小麦品种'小偃6号'(氮高效品种)和'长旱58'(氮低效品种)为材料,采用开顶式气室和土培实验研究了大气NH3浓度升高对生长于高、低两种供氮介质下小麦植株不同生育期叶片净光合速率(Pn)、气孔导度(Gs)、叶绿素含量、叶绿素荧光参数(Fv/Fm、Fv/F0)和可溶性糖含量的影响.结果显示:两小麦品种高氨低氮处理植株的Pn、Fv/F0和可溶性糖含量均高于高氨高氮和低氨低氮处理,并在生育后期差异达显著水平(P＜0.05),氮低效品种的Gs也符合上述规律且不同处理间差异显著(P＜0.05);小麦各生育期高氨高氮处理下植株的Pn均显著低于低氨高氮处理,且两处理间灌浆期的叶绿素含量和灌浆期以前的可溶性糖含量的差异显著(P＜0.05),而两处理灌浆期以前的叶绿素荧光参数Fv/Fm在各处理条件下均无显著差异;不同处理间及品种间各项光合特征指标差异缺乏规律性.可见,大气中NH3浓度升高有利于改善低供氮介质条件下小麦植株的氮营养状况,但不同氮效率品种间的响应存在差异.     

异质低磷胁迫下马尾松家系根构型和磷效率的遗传变异

以7个马尾松(Pinus massoniana)一代种子园自由授粉家系为材料, 设置同质低磷(P)胁迫和异质低P胁迫模拟的盆栽试验, 系统研究马尾松家系对不同类型低P胁迫的适应机制和P效率变异规律。结果表明, 参试马尾松家系的苗高、地径和生物量等P效率指标均表现出显著的家系变异, 主要P效率指标的家系遗传力均较高, 干物质积累量的广义遗传力大于0.80, 揭示了马尾松P营养效率的较大遗传改良潜力。马尾松对不同类型低P胁迫的适应机制有所差异。在同质低P胁迫下, ‘3201’、‘1217’等高P效率家系的根系主要参数均高于低P效率家系, 表明整体根系参数的适应性变化是P效率和生物量形成的决定因素。在异质低P胁迫下, 高P效率马尾松家系在表层富P介质的根系分布量、分布比例均显著增加, 表层根系参数与马尾松家系P效率呈显著正相关, 揭示根系空间构型的适应性变化是决定马尾松高P效率的重要生物学基础。表层根系生物量、表层根相对比例的家系遗传力达0.88和0.72, 证实了以马尾松根构型的适应变化为突破口, 选育具有理想根构型和较高P效率的马尾松家系。     

Genetic variations in root morphology and phosphorus efficiency of Pinus massoniana under heterogeneous and homogeneous low phosphorus conditions

Background and aims

The vertical distribution of available phosphorus (P) in the soil is usually heterogeneous with soil depth. However, little is known about the P efficiency of conifer species under vertically heterogeneous low-P conditions. The purpose of this study was to investigate the genetic variations in growth traits and P efficiency of Pinus massoniana, under heterogeneous and homogeneous low-P conditions.

Methods

Pot experiments consisting of low-P (a low P level in all soil layers), layered-P (a high P level in the topsoil and a low P level in the bottom soil), and high-P (high P levels in all soil layers) conditions were designed and conducted. Three-way ANOVA was used to investigate genetic variations in P efficiency and the major growth traits under these three types of P conditions.

Results

There were substantial genetic variations in the major growth traits, including tree height, stem diameter and seedling dry weight, under both heterogeneous and homogeneous low-P conditions. The heritability for major growth traits was high under both types of low-P condition. Moreover, there were significant genotype × P interaction effects for growth parameters.

Conclusions

Our results indicate that it may be possible to select Masson pine genotypes with high P efficiency and productivity. The significant genotype × environment interactions should be exploited in breeding, and genotypes showing specific adaptations to certain nutrient environments should be bred and used within that environment.     

Effect of aluminum toxicity and phosphorus deficiency on the growth and photosynthesis of oil tea (<Emphasis Type="Italic">Camellia oleifera</Emphasis> Abel.) seedlings in acidic red soils

Wild and cultivated varieties of Camellia oleifera Abel. were studied for the response of their photosynthetic apparatus to Al toxicity and low-P stress in pot experiments with medium of acidic red soil. The effect was measured using physiological processes (growth, photosynthesis, chlorophyll a fluorescence), and pigment contents. The results showed that Al toxicity and low-P stress affected the seedlings’ growth and leaves’ photosynthesis, and the differences could be found between the two varieties. Lime plus P fertilizer treatment led to higher increase in the net photosynthetic rate (Pn) in the cultivar than in the wild variety. Pn increase was positively related to the increase of stomatal conductance (gs) and negatively correlated to intercellular CO₂ concentration (Ci) in both varieties. The maximum PSII quantum yield (Fv/Fm), the efficiency of excitation energy capture by open PSII reaction centers (Fv’/Fm’), the photochemical quenching (qP) and the efficiency of open PSII centers (Φ_PSII) significantly increased almost in all the treatment groups of both varieties, with the exception of an insignificant change in qP value for P₁Al₁ group of cultivar. The insensitive qP and lower Pn for cultivar indicate a higher photosynthetic efficiency for the wild variety, though the Φ_PSII was not significant between the two varieties. The pigment contents of oil tea seedlings under treatments changed significantly when lime and P were added, especially the Car/Chl ratio, suggesting carotenoid plays the role of photoprotection under high-Al and low-P stresses.     

Effects of soil phosphorus and Glomus intraradices on growth,nonstructural carbohydrates,and photosynthetic activity of Citrus aurantium

Sour orange (Citrus aurantium L.) grown in low-P (9–12 ppm) and high-P (420 ppm) soil inoculated with or without Glomus intraradices (G.i.), were evaluated for biomass, carbohydrates, ribulose bisphosphate carboxylase (RuBPCase), phosphoenolpyruvate carboxylase (PEPCase) activity, leaf ¹⁴CO₂ incorporation, and other physiological parameters. Growth of plants in the low-P, noninoculated soil was lowest, with total dry biomass reduced up to half of the low-P, inoculum treatment. Total nonstructural carbohydrates were 40% lower in leaves of plants in the low-P, noninoculated soil, compared with the other treatments. Inoculation of the low-P soil enhanced leaf ¹⁴CO₂ incorporation by 67%, total chlorophyll content by 28%, and RuBPCase activity by 42%, compared with low-P, noninoculated treatment. Improved P-use efficiency by G.i. in low-P soil was comparable to high-P nutrition in improving leaf ¹⁴CO₂ incorporation and concentration of major leaf photosynthetic products that include starch and sucrose. Leaf PEPCase activity in the low-P, noninoculated treatment, however, was at least threefold higher than the other treatments, suggesting a possible alteration in organic acid metabolism in sour orange leaves as a result of P deficiency.     

Exploitation of localized phosphorus-patches by common bean roots

Phosphorus (P) uptake from patches was investigated in high-P and low-P common bean (Phaseolus vulgaris L.) plants using a split-root system. A P-patch was developed by exposing a small sub-section of the root system to localized P enrichment. A soil-based media was used to provide realistically low, buffered levels of P. In addition, nutrient solution provided zero and 1 mM P to low-P and high-P plants, respectively. Overall, growth of low-P plants was approximately 40% that of high-P plants. Mycorrhizal infection by G. etunicatum had little detectable influence on plant growth. Root length exploring a P-patch was comparable for low-P and high-P plants, yet low-P plants allocated half as much root biomass and P to a P-patch compared to high-P plants. This was achieved by an increase in the investment in fine, terminal roots exploring a P-patch in low-P plants. P uptake per investment of dry weight in the P-patch was over 50% higher for high-P plants compared to low-P plants. The higher P-uptake efficiency in high-P plants was achieved despite the greater production of fine roots in low-P plants.     

Influence of Vesicular-Arbuscular Mycorrhizal Fungi on the Response of Potato to Phosphorus Deficiency

Morphological and biochemical interactions between a vesicular-arbuscular mycorrhizal (VAM) fungus (Glomus fasciculatum [Thaxt. sensu Gerdemann] Gerdemann and Trappe) and potato (Solanum tuberosum L.) plants during the development of P deficiency were characterized. Nonmycorrhizal (NM) plants grown for 63 d with low abiotic P supply (0.5 mM) produced 34, 52, and 73% less root, shoot, and tuber dry matter, respectively, than plants grown with high P (2.5 mM). The total leaf area and the leaf area:plant dry weight ratio of low-P plants were substantially lower than those of high-P plants. Moreover, a lower shoot:root dry weight ratio and tuber:plant dry weight ratio in low-P plants than in high-P plants characterized a major effect of P deficiency stress on dry matter partitioning. In addition to a slower rate of growth, low-P plants accumulated nonreducing sugars and nitrate. Furthermore, root respiration and leaf nitrate reductase activity were lower in low-P plants than in high-P plants. Low abiotic P supply also induced physiological changes that contributed to the greater efficiency of P acquisition by low-P plants than by high-P plants. For example, allocation of dry matter and P to root growth was less restricted by P deficiency stress than to shoot and tuber growth. Also, the specific activities of root acid phosphatases and vanadate-sensitive microsomal ATPases were enhanced in P-deficient plants. The establishment of a VAM symbiosis by low-P plants was essential for efficient P acquisition, and a greater root infection level for P-stressed plants indicated increased compatibility to the VAM fungus. By 63 d after planting, low-P VAM plants had recovered 42% more of the available soil P than low-P NM plants. However, the VAM fungus only partially alleviated P deficiency stress and did not completely compensate for inadequate abiotic P supply. Although the specific activities of acid phosphatases and microsomal ATPases were only marginally influenced by VAM infection, VAM roots characteristically had a higher protein concentration and, consequently, enhanced microsomal ATPase and acid phosphatase activities on a fresh weight basis compared with NM roots. Morphological and ultrastructural details of VAM plants are discussed in relation to the influence of the VAM symbiosis on P nutrition of potato.     

Relationship between hypolimnetic phosphorus and iron release from eleven lakes in Maine, USA

We studied five eutrophic (high phosphorus) and six mesotrophic/oligotrophic (low phosphorus) lakes in Maine, USA, all of which are dimictic and develop anoxic hypolimnia during stratification. The lakes were sampled during the stratified period from May to September 1999. Late summer hypolimnetic total phosphorus (P) concentrations in the high-P lakes ranged from 185 to 460ppb; epilimnetic total P increased up to 30ppb from the spring to the fall overturn. During the same period, the low-P lakes had hypolimnetic total P concentrations in the range of 6–19ppb.Individual high-P lakes demonstrated strong temporal correlations between aqueous hypolimnetic dissolved Fe and total P concentrations (R ²0.88) with an average molar Fe:P ratio of 11.9±4.2. For the combined data, the high-P lakes exhibited strong correlation between hypolimnetic Fe and P concentrations (R ²=0.82). The low-P lakes, however, did not show a good correlation between the hypolimnetic Fe and P concentrations. Among the low-P lakes two lakes had hypolimnetic Fe fluxes comparable to the Fe fluxes of the high-P lakes. These two lakes had considerably higher hypolimnetic Fe:P ratios than all other lakes studied here. There were no significant differences in surface sediment Fe(III) or P fractions that correlated with the differences in the relationship between aqueous concentrations of Fe and P in these two outlier low-P lakes. A model for the generation of hypolimnetic acid neutralization capacity (ANC) was developed based on microbially-catalyzed reduction of Fe(III) hydroxide, Mn(IV) oxide and sulfate. Reduction of Fe(III) hydroxide was the most important contributor to the increase in the hypolimnetic ANC in all high-P and the two outlier lakes. Assuming that all hypolimnetic P was due to the reduction of Fe(III) hydroxide by bacteria and sulfide, average summer hypolimnetic P flux for each lake was predicted using the sediment reducible Fe(III):P ratio. The observed and predicted average P fluxes in the high-P lakes corresponded reasonably, suggesting that in these lakes internal P release is closely related to the reduction of Fe(III) hydroxide. Other release or sequestration mechanisms may operate for the release and availability of P in the low-P lakes.     

Phosphorus distribution inside Chinese fir seedlings under different P supplies based on 32P tracer

通过分析杉木(Cunninghamia lanceolata)幼苗磷(P)分配规律, 可以阐明两个磷高效利用杉木在不同供磷水平下吸收外源磷的分配及动态变化, 为进一步进行磷高效利用基因型的选育提供参考。该研究以2个磷高效利用杉木家系(被动忍受型M1与主动活化型M4)幼苗为试验材料, 利用 ³²P同位素示踪技术, 研究在不同供磷水平下2个杉木家系幼苗磷分配规律。结果表明, M1和M4吸收的外源磷的含量分布特征均为根>叶>茎, 自显影中相同处理时期的各器官在水平投影面上 ³²P含量均为根>茎>叶。低磷处理下M1和M4根、茎、叶吸收的外源磷的含量均明显低于高磷处理, 自显影中相同处理时间根、茎、叶低磷水平下成像的黑化程度也低于高磷水平, 且低磷处理下吸收的外源磷的含量增加缓慢, 说明低磷胁迫严重影响杉木苗磷的吸收与积累。M1和M4的根系磷分配率在低磷胁迫下呈现出明显的先减少后增加趋势, 高磷水平下根系磷分配率表现为先增加后趋于平稳。这说明M1和M4可以通过体内磷的重新分配来适应外界低磷胁迫, 即杉木苗在低磷胁迫初期将根系中的磷转移至地上部分, 随着胁迫时间的延长, 地上部分的磷向根系中转移。但两个家系在低磷条件下对吸收的外源磷的分配格局差异明显: 从开始至结束M1吸收的外源磷的分配率表现为根系>地上部分, 而M4先表现为根系>地上部分, 后表现为地上部分>根系, 说明M1在低磷胁迫后加强体内磷循环的程度相比于M4更高, 即磷从地上部分向根系转移的趋势更强烈。     

Phosphorus distribution inside Chinese fir seedlings under different P supplies based on 32 P tracer北大核心CSCD

Aim The objective of this study was to determine the amount and distribution of exogenous phosphorus (P) in different organs, as well as their changes in Chinese fir (Cunninghamia lanceolata) under different P supply levels. The results could be used as scientific base for selecting P-efficient genotypes. Methods Seedlings of two Chinese fir genotypes (M1 and M4), both with high P use efficiency, were treated with different P supply levels and quantified by using 32 P isotope tracer for P distributions in different organs. The seedlings used in this study were selected by our team through previous research as the experimental materials. Important findings We found that the distribution of exogenous P in M1 and M4 was the highest in the roots and the lowest in the stems, and at an intermedia level in the needles. The 32 P content of each organ under the same treatment was ranked as root > stem > needle on the horizontal projection plane. The exogenous P content by the roots, stems and needles of M1 and M4 under low-P treatment appeared lower than that under the high-P treatment. The blackening degree of low-P image of roots, stems and needles under the same treatment was also lower than that under high-P treatment. The content of exogenous P in these organs under the low-P treatment increased slowly, indicating that the low-P stress significantly affected the absorption and accumulation of P in the seedlings. P allocation rates in the roots of M1 and M4 showed an initial decreasing and increasing later under low-P stress, while under the high-P treatment, the root P level increased first and stabilizing later. These findings indicate that M1 and M4 could adapt to external low-P stress through redistribution of P within the plants by transferring P from roots to above-ground parts at the early stage under low P stress. With the extension of stressing time, P from above-ground parts was shifted to roots. However, the distribution of exogenous P in M1 and M4 was significantly different under the low P treatment. The distribution of exogenous P from the beginning to the end of M1 was greater in the roots than that in above-ground parts, while M4 showed a similar pattern in early stages but a higher rate toward the above-ground parts later. This indicates that M1 has a higher degree of strengthening P circulation in vivo than M4 with low P stress, i.e. the tendency of P transfer from above-ground parts to roots is stronger in M1 than in M4. © Chinese Journal of Plant Ecology.