Effect of Benzyladenine and Hydroxybenzyladenosine on Gas Exchange of Bean and Sugar Beet Leaves

Using bean seedlings, the effects of benzyladenine (BA) on stomatal conductance (g_s), transpiration rate (E), and net photosynthetic rate (P_N) were examined in order to find out dose and time responses. In bean seedlings, BA appli roots in concentrations of 1, 5, 10, and 20 µM increased g_s and P_N of leaves already 1 h after application. E was not markedly affected and water use efficiency (WUE) was increased. However, the effects were mostly transient and after 24 h P_N only at 1 and 5 µM BA was increased, and other parameters were not affected or even decreased. In sugar beet seedlings, the effects of hydroxybenzyladenosine (HBA) in addition to those of BA on the same parameters were determined. The both cytokinins were applied in 1, 5, 10, and 20 µM concentrations either to roots or sprayed on leaves However, the effects were inconsistent and the positive effect was observed only after 24 h on P_N in plants with roots immersed in 5 and 10 µM BA, or 10 µM HBA, and on E in plants sprayed with 5 µM BA or 10 µM HBA. Thus the stimulation of gas exchange by exogenously applied cytokinins is rather exceptional than general.     

氮素水平对不同品种茶树光合及叶绿素荧光特性的影响

为探明氮素水平对不同品种茶树的光合系统的影响机制,以‘福鼎大白茶’、‘保靖黄金茶1号’、‘白毫早’两年生茶苗为材料,设置不施氮N_0(0g)、低氮N_1(11g)、中氮N_2(22g)和高氮N_3(33g)4个氮素[(NH_4)_2SO_4]水平的盆栽实验,研究了铵态氮对3个品种茶树的生长势、叶片叶绿素含量、光合参数与叶绿素荧光参数的影响。结果表明:(1)施氮处理能够显著促进茶树的生长,提高茶树叶片叶绿素含量、净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr),降低胞间CO_2浓度(Ci),并以N_2处理最好,但水分利用率(WUE)在3个品种茶树间表现不同。(2)在N_2处理下,3个茶树品种的叶片光系统Ⅱ(PSⅡ)暗适应下的最大光化学效率(F_v/F_m)、光化学猝灭系数(qP)、PSⅡ的相对电子传递速率(rETR)亦增加最大,非光化学淬灭系数(NPQ)降低。(3)茶树叶片叶绿素含量与光合参数间存在着一定的联系,并且具有品种特异性。研究发现,适量施氮能够显著增加茶树叶绿素含量、气孔导度、光合活性,从而使得各品种茶树净光合速率增加;氮素水平对各茶树品种的光合及荧光特性影响存在差异,水分利用率亦具有品种特异性;生产中应综合叶绿素含量、光合作用参数、叶绿素荧光参数,可快速、直观地评价不同品种茶树对氮素营养的内在需求,为茶园施肥管理提供指导。     

Uptake of the Herbicide Diuron as Visualised by the Fluorescence Imaging Technique

A new fluorescence imaging system for monitoring the uptake of the PSII-herbicide diuron (OCMU) was tested in tobacco leaves. UV-laser-induced (Λ_exc = 355 nm) fluorescence images were collected for blue fluorescence F440 (Λ_em = 440 nm), green fluorescence F520 (Λ_em = 520 nm), red chlorophyll fluorescence F690 (Λ_em = 690 nm) and for far-red chlorophyll fluorescence F740 (Λ_em = 740 nm). Diuron-treated leaf parts exhibited a higher red and far-red chlorophyll fluorescence emission (F690 and F740) than untreated leaf halves, whereas the blue and green fluorescence, F440 and F520, remained unaffected. As a consequence, the fluorescence ratios blue/red (F440/F690) and blue/far-red (F440/F740) significantly decreased in diuron-treated leaf parts. The time course of diuron uptake into the leaf could be followed by fluorescence images taken 10 and 30 min after diuron application. The novel high resolution fluorescence imaging method supplies information on the herbicide uptake of each point of the leaf area. Its great advantage as compared to the point data fluorescence measurements applied so far is discussed.     

Effects of Pre-Treatments with Abscisic Acid and/or Benzyladenine on Gas Exchange of French Bean, Sugar Beet, and Maize Leaves During Water Stress and After Rehydration

Net photosynthetic rate (P_N), transpiration rate (E), and stomatal conductance (g_s) during water stress and after rehydration were measured in Phaseolus vulgaris, Beta vulgaris, and Zea mays. Immediately before imposition of water stress by cessation of watering, plants were irrigated with water (control), 100 M abscisic acid (ABA), and/or 10 M N⁶-benzyladenine (BA). In all three species, application of ABA decreased g_s, E, and P_N already 1 h after application. However, during water stress g_s, E, and P_N in plants pre-treated with ABA remained higher than in plants pre-treated with water. Positive effects of ABA application were observed also after rehydration. In contrast, the effects of pre-treatment with BA were species-specific. While in bean plants BA application ameliorated negative effect of water stress, only very slight effects were observed in maize, and in sugar beet BA even aggravated the effects of water stress.     

Measurement of Differences in Red Chlorophyll Fluorescence and Photosynthetic Activity between Sun and Shade Leaves by Fluorescence Imaging

With a flash-lamp chlorophyll (Chl) fluorescence imaging system (FL-FIS) the photosynthetic activity of several thousand image points of intact shade and sun leaves of beech were screened in a non-destructive way within a few seconds. The photosynthetic activity was determined via imaging the Chl fluorescence at maximum F_p and steady state fluorescence F_s of the induction kinetics (Kautsky effect) and by a subsequent determination of the images of the fluorescence decrease ratio R_Fd and the ratio F_p/F_s. Both fluorescence ratios are linearly correlated to the photosynthetic CO₂ fixation rates. This imaging method permitted to detect the gradients in photosynthetic capacity and the patchiness of photosynthetic quantum conversion across the leaf. Sun leaves of beech showed a higher photosynthetic capacity and differential pigment ratios (Chl a/b and Chls/carotenoids) than shade leaves. Profile analysis and histogram of the Chl fluorescence yield and the Chl fluorescence ratios allow to quantify the differences in photosynthetic activity between different leaf parts and between sun and shade leaves with a high statistical significance.     

Rehydration of Sugar Beet Plants after Water Stress: Effect of Cytokinins

The possibility to improve the recovery of sugar beet plants after water stress by application of synthetic cytokinins N⁶-benzyladenine (BA) or N⁶-(m-hydroxybenzyl)adenosine (HBA) was tested. Relative water content (RWC), net photosynthetic rate (P_N), transpiration rate (E), stomatal conductance (g_s), chlorophyll (Chl) a and Chl b contents, and photosystem 2 efficiency characterized by variable to maximal fluorescence ratio (F_v/F_m) were measured in control plants, in water-stressed plants, and after rehydration (4, 8, 24, and 48 h). Water stress markedly decreased parameters of gas exchange, but they started to recover soon after irrigation. Application of BA or HBA to the substrate or sprayed on leaves only slightly stimulated recovery of P_N, E, and g_s in rehydrated plants, especially during the first phases of recovery. Chl contents decreased only under severe water stress and F_v/F_m ratio was not significantly affected by water stress applied. Positive effects of BA or HBA application on Chl content and F_v/F_m ratio were mostly not observed.     

氮素形态对杉木幼苗侧根生长和叶片光合特性的影响

以3月龄的杉木实生苗为试验材料,分析了不同氮素形态——硝态氮(NO₃^- N)、铵态氮(NH4⁺ N)和硝酸铵(NH₄NO₃)(氮素浓度均为3 mmol·L^-1)对杉木幼苗侧根生长、叶片光合气体交换参数和叶绿素荧光参数的影响,以揭示杉木幼苗对不同形态氮的偏好性,以及不同形态氮肥下杉木幼苗侧根生长和光合生理的响应特征,为杉木苗期氮肥管理提供理论依据。结果显示：(1)不同氮素形态对杉木幼苗地上部和侧根生物量具有显著影响,其中NH₄⁺ N处理下幼苗地上部和侧根生物量最大,NO₃^- N处理次之,而NH₄NO₃处理最小。(2)NH₄⁺ N和NO₃^- N处理下杉木幼苗总根长、根系总表面积和根系总体积均显著高于NH₄NO₃处理(P＜0.05),且NH₄⁺ N处理又显著高于NO₃^- N处理,但不同氮形态处理间侧根数量差异不显著。(3)NH₄⁺ N处理下杉木幼苗叶片净光合速率、气孔导度和蒸腾速率明显高于NO₃^- N和NH₄NO₃处理,但NO₃^- N和NH₄NO₃处理之间无明显差异。(4)NH₄⁺ N处理下杉木叶片初始荧光强度低于NO₃^- N处理,而最大荧光强度、可变荧光强度和PSⅡ潜在活性却高于全硝氮和硝铵氮处理。上述结果表明,NH₄⁺ N处理不仅有利于杉木幼苗侧根生长发育,且其叶片具有较强的光合能力,较高的PSⅡ中心稳定性、光化学活性以及电子传递效率,从而更有利于植株生长。因此,从根系生长和光合特性来看,杉木幼苗对铵态氮具有偏好性。     

固定化培养中氮磷浓度对钝顶螺旋藻生长及其代谢产物和叶绿素荧光参数的影响

该研究以钝顶螺旋藻为实验对象,探究培养基中不同氮浓度(5、15、30、45 mmol·L^-1)和磷浓度(0.5、1.5、3.0、4.5 mmol·L^-1)对固定化生物膜培养模式下螺旋藻生长及其代谢产物和叶绿素荧光参数的影响,为生产实际中规模化高效培养螺旋藻提供理论依据。结果表明：(1)随着氮、磷浓度的升高,螺旋藻的生物量密度和产率先增高后降低,并在30 mmol·L^-1氮和3.0 mmol·L^-1磷处理时达到最大值;低氮、低磷条件会影响螺旋藻的藻体结构,表现为单细胞藻丝变短,螺旋变少,导致生物膜细胞密度降低。(2)与生物量变化趋势一致,螺旋藻光合色素含量随着培养基中氮、磷浓度的增加呈先升后降的变化趋势,且均在30 mmol·L^-1氮或者3.0 mmol·L^-1磷条件下达到最大值。(3)培养基中磷浓度固定时,螺旋藻的PSⅡ反应中心最大光能转化效率(F_v/F_m)和电子传递速率(ETR)随着氮浓度增加而增大,氮的缺乏会...     

盐胁迫对朴树和速生白榆幼苗光合特性及叶绿素荧光参数的影响

以1年生的朴树和速生白榆幼苗为试材,采用山东省林业科学研究院东营分院34.6‰的地下天然盐水配制所需盐水浓度,定期定量浇灌,使土壤分别达0（CK）、2‰、2.5‰、3.5‰和5‰的含盐量,各处理胁迫45 d后测定其生长量（地径、苗高）、叶绿素含量、光合参数以及叶绿素荧光特性的变化,研究不同盐胁迫处理对朴树和速生白榆生长及光合作用的影响,探究其耐盐能力。结果显示: （1）整个盐胁迫过程中速生白榆的生长量较朴树高,但随着盐胁迫强度的增加朴树幼苗叶绿素含量呈先升高后降低的变化趋势,速生白榆幼苗则低于CK呈下降趋势。（2）朴树和速生白榆初始荧光（F_o）、最大荧光（F_m）和PSⅡ最大光能转化效率(F_v/F_m)均表现出下降趋势,与朴树相比速生白榆的F_o、F_m和F_v/F_m下降不明显,但在＞2.5‰盐胁迫下速生白榆的非光化学猝灭系数（NPQ）较朴树增加更明显。研究表明,朴树叶绿素含量在每个盐胁迫浓度下均显著高于速生白榆,但在大于2.5‰浓度胁迫下速生白榆的荧光参数变化较朴树占优势;在非环境胁迫及较低盐胁迫条件下（≤2.5‰）,朴树较速生白榆具有更好的光化学性能,但在较高盐胁迫条件下（＞2.5‰）,速生白榆光合参数及荧光参数较朴树变化稳定,能更好的适应盐胁迫环境。     

Immunohistological Analysis of Chemically Induced Proteins in Sugar Beet

Tissue-specific distribution of basic β-1,3-glucanase (Glu2), basic class II chitinase (Ch2), basic class IV chitinase (Ch4), and acidic class III chitinase (SE2) were examined both in leaves and roots of sugar beet treated with salicylic acid (SA), benzothiadiazole (BTH) and glycine betaine. Protein localization was monitored by immunohistological analysis using specific antibodies. BTH, SA as well as glycine betaine induced both Glu2 and chitinase isozymes in leaves and roots of treated plants. The enzymes were accumulated in extracellular space and cell walls. They were mostly deposited in parenchyma cells of leaves and cortex parenchyma and endodermis of roots. In leaf tissues, BTH and SA induced proteins more effectively than glycine betaine but the effect of glycine betaine in roots was as efficient as BTH and SA. Glycine betaine induced the formation of extracellular globuli containing Ch4. Induced proteins were spatially distributed over the whole plant regardless the site of the inducer application. This revised version was published online in July 2006 with corrections to the Cover Date.     

施氮时期对酿酒葡萄叶片氮代谢酶及相关基因表达的影响

以10年生‘蛇龙珠’葡萄为材料,在萌芽期(S1)、新梢旺长期(S2)、开花期(S3)、果实第一次膨大期(S4)、副梢生长旺期(S5)和果实第二次膨大期(S6)分别一次性施入尿素300kg·hm-2,以不施氮肥为对照(CK),分析了花前5d(DBF5)、花后25d(DAF25)、花后55d(DAF55)和花后85d(DAF85)叶片的各项指标,以明确氮素施用时期对葡萄叶片氮代谢的调控与影响。结果表明:(1)S1和S2处理葡萄叶片中总氮及可溶性蛋白含量在DAF25时显著增加。(2)S3和S4处理的NR及GS活性在DAF85时显著高于其他处理;在DAF25时,S1和S2处理的GOGAT活性,以及S3和S4处理的GDH活性均显著高于同期对照和其他施肥处理。(3)各施肥处理叶片VvNR表达水平在不同时期均高于同期对照,S3处理VvNR表达水平在DAF25和DAF85时分别为对照的3.4倍和2.7倍;S3和S4处理的VvGS表达水平分别在DAF55和DAF85时达到最高值,S3处理的VvGOGAT和S4处理的VvGDH表达水平在DAF55和DAF85均显著高于其他处理,S3处理的VvGDH表达水平在DAF55和DAF85仅次于S4处理。研究表明,氮素通过诱导叶片氮素代谢基因的响应,从而调控叶片中氮素代谢酶活性增加,促进了氮素的积累,S3和S4处理在不同时期氮代谢酶活性和对应的基因表达水平均较高,更有利于叶片中氮素的转化和代谢。     

New Fluorescence Parameters for the Determination of QA Redox State and Excitation Energy Fluxes

A number of useful photosynthetic parameters are commonly derived from saturation pulse-induced fluorescence analysis. We show, that q(P), an estimate of the fraction of open centers, is based on a pure 'puddle' antenna model, where each Photosystem (PS) II center possesses its own independent antenna system. This parameter is incompatible with more realistic models of the photosynthetic unit, where reaction centers are connected by shared antenna, that is, the so-called 'lake' or 'connected units' models. We thus introduce a new parameter, q(L), based on a Stern-Volmer approach using a lake model, which estimates the fraction of open PS II centers. We suggest that q(L) should be a useful parameter for terrestrial plants consistent with a high connectivity of PS II units, whereas some marine species with distinct antenna architecture, may require the use of more complex parameters based on intermediate models of the photosynthetic unit. Another useful parameter calculated from fluorescence analysis is Phi(II), the yield of PS II. In contrast to q(L), we show that the Phi(II) parameter can be derived from either a pure 'lake' or pure 'puddle' model, and is thus likely to be a robust parameter. The energy absorbed by PS II is divided between the fraction used in photochemistry, Phi(II), and that lost non-photochemically. We introduce two additional parameters that can be used to estimate the flux of excitation energy into competing non-photochemical pathways, the yield induced by downregulatory processes, Phi(NPQ), and the yield for other energy losses, Phi(NO).     

Glycine betaine accumulation,ionic and water relations of red-beet at contrasting levels of sodium supply

Exposure of plants to sodium (Na) and salinity may increase glycine betaine accumulation in tissues. To study this, red-beet cvs. Scarlet Supreme and Ruby Queen, were grown for 42 days in a growth chamber using a re-circulating nutrient film technique with 0.25 mmol/L K and either 4.75 mmol/L (control) or 54.75 mmol/L (saline) Na (as NaCl). Plants were harvested at weekly intervals and measurements were taken on leaf water relations, leaf photosynthetic rates, chlorophyll fluorescence, chlorophyll levels, glycine betaine levels, and tissue elemental composition. Glycine betaine accumulation increased under salinity and this accumulation correlated with higher tissue levels of Na in both cultivars. Na accounted for 80 to 90% of the total cation uptake under the saline treatment. At final harvest (42 days), K concentrations in laminae ranged from approximately 65-95 micromoles g-1 dry matter (DM), whereas Na in shoot tissue ranged from approximately 3000-4000 micromoles g-1. Leaf sap osmotic potential at full turgor [psi(s100)] increased as lamina Na content increased. Glycine betaine levels of leaf laminae showed a linear relationship with leaf sap [psi(s100)]. Chlorophyll levels, leaf photosynthetic rates, and chlorophyll fluorescence were not affected by Na levels. These results suggest that the metabolic tolerance to high levels of tissue Na in red-beet could be due to its ability to synthesize and regulate glycine betaine production, and to control partitioning of Na and glycine betaine between the vacuole and the cytoplasm.     

极端干旱区疏叶骆驼刺叶绿素荧光对人工水分干扰的响应特征

选取塔里木河下游天然植被恢复示范区的疏叶骆驼刺(Alhagi sparsifolia Shap.)为研究对象,测定每年引水灌溉2次(每次0.42m3/m2)、1次和不灌溉(CK)处理下疏叶骆驼刺的实际光化学量子产量(ΦPSⅡ)、电子传输速率(ETR)和光化学猝灭系数(qP)等叶绿素荧光参数及其叶水势变化,探讨疏叶骆驼刺对人工水分干扰的叶绿素荧光响应特征。结果表明:(1)随着灌溉量的减少,疏叶骆驼刺叶水势呈显著降低的趋势,并在CK下达到最低。(2)同期疏叶骆驼刺qP、ΦPSⅡ、ETR、最大光量子产量(Fv/Fm)、叶绿素含量和光饱和点均随着灌溉量的减少呈先增加后降低的趋势,非光化学淬灭系数(NPQ)和调节性能量耗散(YNPQ)则呈先降低后增加的趋势。(3)与每年1次灌溉量处理相比,不灌溉和每年2次的灌溉量处理下疏叶骆驼刺发生了光抑制,光能捕获效率与光化学反应能量下降,热耗散能力提高。研究认为,灌溉量过高(每年2次,0.84m3/m2)或不灌溉均会限制疏叶骆驼刺光化学效率和光和活性,适时适量的(春季灌水1次,0.42m3/m2)水分补给更有利于疏叶骆驼刺适应干旱胁迫并维持正常光合生长。     

Effect of Benzylaminopurine on Rehydration of Bean Plants after Water Stress

The possibility of improving the recovery of plant photosynthesis after water stress by cytokinin-induced stimulation of stomatal opening or delay of leaf senescence was tested. The 6-benzylaminopurine (BAP) in concentrations 1 and 10 M was applied to the substrate (sand + nutrient solution) or sprayed on primary leaves of 14-d-old Phaseolus vulgaris L. plants sufficiently supplied with water or water-stressed for 4 d. The later ones having relative water content decreased to 69 % were fully rehydrated during the following three days. Parameters of photosynthesis and water relations were measured in primary leaves of 7-, 10-, 14-, and 17-d-old plants. Application of 1 M BAP slightly delayed leaf senescence: in 17-d-old control plants, net photosynthetic rate (P_N) and chlorophyll (Chl) content, and when sprayed on leaves also some of Chl a fluorescence kinetic parameters of BAP-treated leaves were slightly higher than those of untreated leaves. Both types of application of 1 M BAP slightly improved recovery of plants during rehydration after water stress in terms of increased g_ad, g_ab and P_N, i.e., parameters which were markedly decreased by mild water stress. However, contents of Chl a, Chl b and carotenoids and parameters of Chl a fluorescence kinetic were not markedly affected by mild water stress and after rehydration were not stimulated by 1 M BAP. 10 M BAP had mostly negative effects on the parameters measured.     

Fertilizer nitrogen budgets of 15N-labelled sugarbeet (Beta vulgaris) tops and Na 15NO3 dressings split-applied to winter wheat (Triticum aestivum) in microplots on a loam soil

The fate of N from sugarbeet (Beta vulgaris L.) tops returned to the soil (50 T ha^-1) in autumn 1986 before sowing winter wheat (Triticum aestivum L.), and from NaNO₃ split-applied in 3 equal dressings (at tillering, stem elongation and flag leaf stages) was studied using isotopically labelled ¹⁵N in open stainless-steel cylinders pressed into the soil.At harvest, the percentage utilization (PU) of N from sugarbeet was very low (6.66%) and negatively influenced by fertilizer N (5.59%), while that of fertilizer N was rather high (69.64%) and unchanged by addition of tops. Residual N in soil represented 25.9% of the amount applied in tops and ranged from 33% for the tillering application to 21% for the flag leaf application. N losses (mainly denitrification) from sugar beet tops amounted to 67% and were very low for mineral fertilizer (less than 5%).     

根域体积限制对芹菜幼苗生长和气体交换及叶绿素荧光参数的影响

以芹菜品种‘皇后’为试材,采用自配育苗基质(柠条粉∶珍珠岩∶蛭石=7∶2∶1体积比),按照不同根域体积(110.07、67.20、39.06、26.82、19.76、12.21、7.28cm3/穴)进行育苗,探索在柠条混配基质条件下不同根域体积水平对芹菜幼苗生长、气体交换和叶绿素荧光动力学诱导曲线的影响,为柠条混配基质条件下设施蔬菜育苗提供科学依据。结果表明:(1)芹菜幼苗株高、叶片数、根长、根系体积、地上部鲜质量、地上部干质量、地下部鲜质量和地下部干质量均随着根域体积的减小而降低;根域体积最大(110.07cm3/穴)时的净光合速率和蒸腾速率分别比根域体积最小(7.28cm3/穴)时高出64.13%和18.87%。(2)气孔导度变化总体随着根域体积的减少而减少,胞间CO2浓度变化总体受根域体积影响不大。(3)根域体积过大(110.07cm3/穴)或偏小(7.28cm3/穴)都会影响PSⅡ光合电子传递,均使得PSⅡ反应中心用于热耗散的能量高于用于电子传递的能量,用于电子传递的量子产额(φEo)、ψo值、单位面积捕获的光能(TRo/CS)和单位面积捕获的光能(TRo/CS)分别在根域体积为25.68、14.34、17.32和19.21cm3/穴时达到最大。研究认为,根域体积限制直接影响着芹菜幼苗气体交换和叶绿素荧光参数的变化,进而影响幼苗的光合作用及生长。     

Photosynthetic Characteristics of Chloroplasts of Primary Wheat Leaves Grown under Different Irradiance

The rate of accumulation of total chlorophyll (Chl) and carotenoids (Car) of leaves grown under high irradiance, HI (30 and 45 W m^–2) was faster than at moderate irradiance, MI (15 W m^–2). However, the senescence phase started earlier in the samples and proceeded at a faster rate. Chl a/b and Chl (a+b)/Car values showed faster loss of Chl a (compared to Chl b) and Chl (a+b) (compared to Car) in HI leaves. Protein accumulation and loss were also similar to that of Chl (a+b) content. Increase in Chl fluorescence during the development phase may suggest a gradual change in thylakoid organisation, however, the temporal kinetics were different in HI and MI samples. Increase in fluorescence polarisation during senescence of HI leaves compared to the control (MI) suggests conversion of thylakoid membranes to gel phase. Chloroplasts prepared from HI seedlings showed higher rate of photochemical activities, however, the activity declined earlier and at faster rate compared to the control.     

不同氮素水平对油麦菜栽培效果的综合评价分析

为探讨不同氮素水平的硝态氮与铵态氮对油麦菜(Lactuca sativa L.)生长及品质的影响,自主设计并制作了适合蔬菜水培的立体管道栽培系统,配制了NO3-：NH4+=10：0,NO3-：NH4+=7：1,NO3-：NH4+=7：3的营养液,通过模糊数学原理,采用层次分析法(AHP)确定品质的权重值,综合评价了不同氮素水平对油麦菜的栽培效果。结果表明,以NO3-：NH4+=7：3营养液的栽培效果最好,其次是NO3-：NH4+=7：1。当营养液的NO3-：NH4+=7：3时,油麦菜的产量最高,叶片叶绿素、可溶性糖、可溶性蛋白质含量最高,硝酸盐含量最少,其综合品质最好。层次分析法对油麦菜不同氮素水平营养液的栽培效果的综合评价有较好的适用性,有助于获得南方设施管道栽培油麦菜最佳的营养液配方。     

干旱胁迫下油橄榄品种光合特性研究

为揭示油橄榄(Olea europaea L.)耐旱性与光合特性之间的关系,以筛选出的适宜于半干旱川西南地区种植的7个引进油橄榄品种为供试材料,采用盆栽模拟干旱胁迫的方法,研究持续干旱胁迫对其光合特性的影响。结果表明:(1)随着干旱胁迫程度加剧,7个油橄榄品种叶片相对含水量均显著降低,至干旱胁迫后期(25d),各品种叶片均出现大幅失水,其中品种‘科拉蒂’失水率最高(45.79%),而品种‘小苹果’失水率最低(25.52%),说明‘小苹果’叶片在干旱胁迫下较其他油橄榄品种具有更高保水能力。(2)随着干旱胁迫程度加剧,7个油橄榄品种叶片光合色素含量均不同程度降低,表明光合色素分解量大于合成量;干旱胁迫持续25d时,品种‘豆果’的叶绿素a和叶绿素b含量下降幅度最大(P0.05),品种‘皮削利’类胡萝卜素含量下降幅度最大(P0.05),而品种‘小苹果’叶绿素a含量下降幅度最小。(3)随着干旱胁迫的持续进行,各油橄榄品种叶片净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)和胞间CO2浓度(Ci)均不同程度降低,而水分利用效率(WUE)则呈上升趋势;干旱胁迫期间,品种‘佛奥’的Pn、Tr和Ci以及‘皮削利’的Gs降幅均高于其他品种,而‘小苹果’的Pn、Gs和Ci降幅均为最小且WUE上升幅度最大。研究发现,在持续干旱胁迫条件下,油橄榄幼苗叶片均大幅失水,光合色素结构被破坏、色素分解、含量降低,同时气孔关闭蒸发减少,光合作用减弱,而供试油橄榄品种中‘小苹果’对干旱胁迫的适应性最强,适宜于在半干旱的川西地区种植。