不同品种菠菜叶柄和叶片的硝态氮含量及其与植株生长的关系

温室盆栽试验研究了我国北方不同菠菜品种叶柄和叶片的硝态氮含量及其与植株生长的关系。结果表明,30个菠菜品种地上部分的生长量和硝态氮含量存在显著差异。叶柄和叶片在反映品种间生长量和硝态氮含量变异方面的作用并不相同。叶片占植株地上部鲜重的比例高于叶柄,品种间叶片生长量的差异亦大于叶柄,叶片与植株生长量的正相关关系更为显著。但与生长量的情况不同,叶柄的硝态氮含量、累积总量均显著高于叶片,是菠菜累积硝态氮的主要器官。叶柄硝态氮含量的品种间差异远大于叶片,与植株地上部硝态氮含量的正相关性更为显著。菠菜不同品种之间,叶柄硝态氮含量与地上部鲜重、干重及水分均表现出显著的正相关关系,而叶片硝态氮含量与植株生物量及其各组分之间却无这种关系。     

菠菜叶片硝态氮还原对叶柄硝态氮含量的影响

选用3个菠菜品种,设置N.0.1和0.3.g/kg2个施氮水平进行盆栽试验。在不同时期采样测定叶片内、外源硝酸还原酶活性、硝态氮代谢/贮存库大小,以及加入外源硝态氮培养后叶片硝酸还原酶活性的变化,探讨菠菜叶片的硝态氮还原与叶柄硝态氮含量的关系。结果表明,叶片内源硝酸还原酶活性、内源/外源硝酸还原酶活性比值、叶片的硝态氮代谢库大小及代谢/贮存库比值与叶柄硝态氮含量呈相反趋势。加入外源硝态氮培养后叶片硝酸还原酶活性的增加程度与叶柄硝态氮含量相一致。叶片内源硝酸还原酶活性高低及其发挥程度,叶片硝态氮代谢库大小及硝态氮在代谢、贮存库中的分配是造成品种间叶柄硝态氮含量高低差异的重要原因。     

小白菜适当增铵下硝酸盐累积机理研究

利用NO3--N/NH44+-N为100∶0和75∶25的营养液对两个硝酸盐累积能力显著不同的小白菜品种(上海青和亮白叶1号)进行培养,测定了小白菜叶片、叶柄及根系硝酸盐含量、硝态氮和铵态氮吸收量及各部位硝酸还原酶活性,以探讨适当增铵降低小白菜硝酸盐含量以及小白菜不同品种和不同器官累积硝酸盐能力差异的机理。结果表明,适当增铵使叶片、叶柄和根系硝酸盐含量分别降低了22%、15%和22%,而硝态氮吸收量则降低了7.5%。小白菜各器官硝酸盐含量为叶柄叶片根系。叶片硝酸还原酶活性分别是叶柄和根系的27和9倍,呈现叶片根系叶柄,叶片是硝态氮的主要还原器官。亮白叶1号叶片、叶柄及根系硝酸盐含量分别较上海青高3%、38%和34%,硝态氮吸收量仅较上海青高11%;而叶片、叶柄及根系硝酸还原酶活性则分别较后者降低44%、56%和38%。适当增铵减少硝态氮吸收量是增铵降低硝酸盐含量的主要原因。不同器官的功能与结构的不同决定其累积硝酸盐能力的不同;不同品种硝酸盐累积的差异取决于还原硝态氮能力的差异。     

不同氮肥用量对蔬菜硝态氮累积的影响

利用盆栽试验,研究了氮肥用量对蔬菜硝态氮累积的影响。结果表明,施用氮肥使蔬菜的生长量提高1.1～6.1倍,但增长并不与氮肥用量同步。氮肥用量较高时,蔬菜生长受到抑制,生长量有降低趋势;硝态氮含量却随氮肥用量增加而不断升高,两者呈显著正相关（r=0.933～0.957）。蔬菜各器官、部位的硝态氮含量存在明显差异。不施氮肥时,根的硝态氮含量大于茎叶,茎又大于叶;施氮后根的含量小于茎叶,茎小于叶;无论施氮与否,叶柄的含量均高于叶片。把蔬菜的生长、硝态氮吸收及还原转化联系起来分析,可以看出,增加氮肥用量虽然提高了硝酸还原酶活性,但硝态氮的还原作用仍小于吸收,从而导致蔬菜体内出现硝态氮累积。而且,随氮肥用量增加,硝态氮累积量的增加远超过了生长量的提高,使硝态氮含量迅速升高。     

氮素形态对菠菜可食部分硝酸盐和草酸累积的影响

采用溶液培养试验研究了营养液中硝态氮/铵态氮比例对菠菜地上部可食部分不同器官硝酸盐以及不同形态草酸累积的影响。结果表明,菠菜地上部生物量随供铵比例从0%提高到50%呈增加趋势而后显著下降。叶片和地上部可食部分的硝酸盐含量和累积量均随供铵比例增加而显著下降;叶柄的硝酸盐含量随供铵比例提高而降低,而硝酸盐积累量则先升高后显著下降。叶片是菠菜积累草酸的主要器官,可溶态草酸与草酸总量分别占地上部的56.3%～89.8%和76.6%～87.4%。可溶态草酸是菠菜体内草酸的主要形态,在叶片、叶柄及地上部中所占草酸总量的比例分别在36.7%～83.5%,79.0%～93.3%以及50.0%～83.0%之间。地上部各器官的可溶态草酸含量、难溶态草酸含量和草酸总量以及积累量均随着供铵比例的增加而显著下降,叶片和地上部的草酸含量和积累量的下降幅度均高于叶柄。可见,调节营养液中硝态氮/铵态氮比例可以有效降低菠菜地上部可食部分硝酸盐和草酸的含量和积累量,50/50是营养液中适宜的硝态氮/铵态氮比例,不仅菠菜的生物量最高,而且硝酸盐和各形态草酸的含量以及累积量较低,从而大大减轻了硝酸盐和草酸对人体健康产生的负面影响。     

施氮、钾和钼对菠菜不同生长阶段硝态氮积累影响研究初报

采用盆栽试验研究了肥料(氮、钾、钼)互作对菠菜不同生长阶段硝态氮积累的影响。结果表明,施肥对菠菜硝态氮积累的影响整体表现为:柄叶,老叶新叶;与生长前期相比,收获期各部位中硝态氮含量均有下降趋势。不施氮条件下,施钼极显著或显著地降低了菠菜生长前期和收获期叶片中硝态氮含量,降幅分别为19.3%和21.4%;施氮条件下,施钼仅显著降低了菠菜生长前期叶片中硝态氮含量,降幅达21.2%。在本试验条件下,单施钼比钼钾配施更有利于降低菠菜叶片中硝态氮的含量;钾与钼营养的相互效应,以及钾与钼之间如何平衡,似乎是影响施钼效果的关键。     

氮形态和硫水平对烤烟氮、硫、钾等营养的影响

红壤和潮土培育烤烟,100%铵态氮、100%硝态氮和50%铵氮+50%硝氮等3种氮形态和2种硫施用量的盆栽试验研究表明,增加硝态氮肥供给比例,有利于烤烟生长,烟株叶片干重、株高、干径增加。施硫增加,各叶位全硫含量均显著增加,下部叶片明显累积较多的硫。硝态氮处理红壤和潮土生长烟叶硫含量降低。烟叶氮含量也受供氮形态影响,硝态氮供给比例增加,烟叶全氮含量均较高。供硫增加,烟叶钾含量下降;100%铵氮处理烟叶钾累积较多,NH4+没有抑制K的吸收。     

铵硝比和磷素营养对菠菜生长、氮素吸收和相关酶活性的影响

通过水培试验研究了不同铵硝比的氮素营养和磷素营养对菠菜生长、氮素吸收及硝酸还原酶活性（NRA）和谷氨酰胺合成酶活性（GSA）的影响。结果表明：在供磷水平相同时，菠菜的生物量随着铵硝比的降低而降低，但铵硝比为25：75与0：100两个处理之间没有显著差异；在铵硝比相同时，随着营养液中磷含量的增加，菠菜的生物量随之增加。菠菜茎叶中硝酸盐的含量随着铵硝比和磷水平的降低而升高。不同铵硝比处理，菠菜含氮量没有明显差异，随着磷水平的提高，菠菜植株含氮量有升高的趋势，但各处理之间差异不显著；受到生物量显著差异的影响，菠菜植株中氮素累积量随着铵硝比的降低和磷素水平的增加而增加。在铵硝混合营养条件下，缺磷会显著抑制菠菜对铵态氮和硝态氮的吸收，且磷索缺乏对菠菜吸收硝态氮的抑制作用要大于对铵态氮吸收的抑制作用。铵硝比相同时，随着营养液中磷索供应量的增加，菠菜茎叶中NRA显著增加；但是营养液中铵硝比较高时，会显著抑制菠菜茎叶中NRA，而铵硝比较低时，则有利于提高菠菜的NRA。缺磷会严重抑制GSA；在磷素水平相同时，随着营养液中铵比例的增加，菠菜茎叶中GSA显著增加。为此，在一些硝酸盐含量较高的土壤上栽培蔬菜时，可以采取增施适量磷肥的方法，以降低叶菜的硝酸盐含量。     

氮素形态和光照强度对烟草生长和H2O2清除酶活性的影响

氮素形态和光照强度对烟草植株生长和H2O2清除酶活性影响的研究结果表明,在弱光下,氮素形态不影响植株生长,但在强光下,铵态氮明显抑制植株的生长。弱光下供应按态氮叶片叶绿素含量显著地高于供应硝态氮的叶片;而强光下供应铵态氮叶片单位鲜重叶绿素含量反而显著地低于供应硝态氮的叶片。强光下供应按态氮的叶片中MDA含量明显高于供应硝酸盐的叶片,但在弱光下则无明显的差异。供应硝态氮叶片中AsA含量高于供应铵态氮的叶片;但供应铵态氮叶片中DAsA含量高于供应硝态氮叶片,尤其是强光下其差异更大。光照强度的增加明显提高AsA-POD、MDAsA还原酶、DAsA还原酶和GSSG还原酶活性。强光下供应镀态氮叶片中AsA-POD和GSSG还原酶活性明显地高于供应硝态氮的叶片,而MDAsA还原酶活性则相反。弱光下供应铵态氮叶片AsA-POD和MDAsA还原酶活性明显高于供应硝态氮的叶片,而GSSG还原酶活性的差异则不显著。铵态氮不显著提高DAsA还原酶的活性。SOD和CAT活性在各处理之间差异不明显。增加光照强度和供应铵态氮都明显地提高AsA氧化酶活性。     

不同供氮水平下油菜品种硝态氮累积利用特征与氮效率差异

以两种氮效率不同的油菜品种X-13和X-29为材料,在严格控制氮营养水平的砂培条件下,研究了不同施氮水平下两个品种油菜硝态氮累积量、硝酸还原酶活性、氮素吸收量、籽粒产量、氮效率等指标的差异特征。结果表明,与氮低效品种X-29相比,氮高效品种X-13的硝态氮累积量多,硝态氮再利用量大,叶片硝酸还原酶活性高,其氮素累积量也多,籽粒产量和氮效率也高,品种间差异显著。供氮水平提高,两品种的硝态氮累积量和再利用量都增大,叶片硝酸还原酶活性增强,氮素随着累积量增加,籽粒产量升高,而氮效率则下降。     

NITRATE IN LEAF PETIOLE AND BLADE OF SPINACH CULTIVARS AND ITS RELATION TO BIOMASS AND WATER IN PLANTS

A pot experiment was carried out, with 30 spinach cultivars to determine nitrate accumulation in leaf blade and petiole, and its relationship to biomass and water in plants. Results showed that the fresh weight proportion of blade to shoot was higher than that of petiole. Furthermore, a higher positive correlation was found between fresh weights of blades and shoots than that of petioles and shoots. Unlike biomass, nitrate-nitrogen (N) concentration and total amount of nitrate-N accumulated in petiole were significantly higher than those in blade, and petiole was obviously the main organ for nitrate accumulation. Differences of nitrate-N concentration in petiole and the observed positive correlation between nitrate-N concentrations in petioles and shoots were more significant than that in blades and shoots. Nitrate-N concentration in petiole was also significantly correlated with fresh and dry shoot weight and total amount of water in shoots. However, this relationship was not found for blade.     

Spatiotemporal changes of nitrate and Vc contents in hydroponic lettuce treated with various nitrogen-free solutions

Abstract

Nowadays, off-season leafy vegetables are generally characterized by low vitamin C (Vc) content and high nitrate accumulation due to low light intensity inner protected systems and high-level nitrogen supply. A glasshouse experiment was conducted to investigate the effects of three kinds of nitrogen-free solution treatments before harvest on Vc and nitrate contents in expanded leaf blades, expanded leaf petioles and old leaves of hydroponic lettuce. The results showed that using nitrogen-free solutions could decrease nitrate contents of expanded leaf blades, expanded leaf petioles and old leaves, also nitrate contents in above parts reduced increasingly with treatment time extending. In addition, three nitrogen-free solution treatments increased the Vc content of expanded leaf blades instead of expanded leaf petioles and old leaves. There were instead of significant positive correlations between nitrate contents but Vc contents of expanded leaf blades, expanded leaf petioles and old leaves. To conclude, nitrogen disruption treatment before harvest could effectively reduce nitrate contents in edible parts of lettuce, and also improve Vc content in expanded leaf blade.     

玉米叶片SPAD值、全氮及硝态氮含量的品种间变异

研究比较两种土壤肥力条件下,4个春玉米品种在喇叭口期至成熟期间叶片SPAD值、全氮及硝态氮含量的变异程度、及其与氮素积累和产量形成的关系,以期为不同品种植株的氮素营养测试指标的优化提供依据。结果表明,叶片SPAD值与产量、吸氮量及生物量呈显著相关,该值主要受氮肥水平影响,并因土壤肥力而变异。从喇叭口期至灌浆期间平均变异幅度为17.7%,但品种间变异很小,平均仅为4.3%。说明利用SPAD值诊断玉米氮素营养时,其诊断指标不需要因品种而调整,但需要因不同肥力而调整。在新立城低肥力条件下,喇叭口期(V12)和抽雄期(VT)的SPAD临界值指标分别为46.1和57.8;在德惠高肥力条件下,两个时期的SPAD值临界值较为接近,分别为59.9和60.3。植株叶片硝态氮含量在土壤肥力间及品种间变异均较大,变异幅度分别为43.1%和29.3%,且与产量、吸氮量及生物量的相关性均较差,不适于在大面积范围内单独作为玉米氮素营养状况的评价指标。     

Differential response of two taro cultivars to aluminum: I. Plant growth

Abstract

Aluminum (Al) toxicity is one of the major factors limiting plant growth in acid soils. To determine the response of taro [Colocasia esculenta (L.) Schott] to Al‐toxicity, cultivars (cv.) Lehua maoli and Bun long were grown in hydroponic solution at six initial levels of Al (0, 110, 220, 440, 890, and 1330 uM Al). Increasing Al levels significantly depressed fresh and dry weights of taro leaf blades, petioles, and roots, as well as leaf areas and root lengths. No significant cultivar differences were found for plant dry weights. However, significant cultivar differences were found for expansion growth parameters, with cv. Lehua maoli exhibiting greater leaf fresh weights and root lengths in the presence of Al, compared to cv. Bun long. Apparently, differential response of taro cultivars to Al is related to the ability of the Al‐tolerant cultivar to maintain water uptake and cell expansion in the presence of Al. The initial solution Al level that resulted in the greatest separation of growth differences between taro cultivars in their response to Al was 890 μM Al.     

硝化抑制剂对小白菜内源硝酸盐代谢的影响

为了提高蔬菜体内硝态氮的代谢有效利用性,采用土培盆栽试验方法,以NO3-N︰NH4+-N为2︰3的处理(以S1表示)为对照,研究在对照基础上分别添加3种硝化抑制剂(即,双氰胺、咪唑、吡啶,分别以S2、S3、S4表示)对小白菜内源硝酸盐代谢的影响。结果表明:3种硝化抑制剂的添加可提高小白菜产量6.06%~28.55%,增加植株氮吸收量2.38%~38.42%,降低蔬菜硝酸盐含量2.69%~19.66%,分别提高小白菜叶片硝酸还原酶活性、叶肉细胞硝态氮的代谢库大小和贮藏库大小24.28%~77.32%、29.45%~272.17%和2.78%~17.38%,并增加代谢库与贮藏库的比值0.04%~0.59%,从而提高了小白菜内源硝酸盐的有效利用性。其中,以S2处理对提高小白菜内源硝酸的有效利用性相对最佳,植株产量和植株氮吸收量相对最高,分别为56.72 g.盆1和0.156 g.盆1;植株硝酸盐含量较低,为1 749 mg·kg-1;而叶片的硝酸还原酶活性和叶肉细胞硝态氮代谢库相对最高,分别为1.90μg(NO2-N).30 min-1·g-1(FW)和0.33μg(NO2-N)·g-1(FW)。     

Sensitivity of soft red winter wheat cultivars to chlorate‐induced toxicity

The use of chlorate as a nitrate analogue to screen soft red winter wheat (Triticum aestivum L.) cultivars for differences in nitrate reductase activity (NRA) was studied by adding potassium chlorate to a hydroponic nutrient solution in which wheat seedlings were growing. After 14 days, leaf symptoms indicating chlorate‐induced toxicity were rated. It was hypothesized that wheat plants which were susceptible to chlorate‐induced toxicity reduced chlorate and nitrate more rapidly than did resistant plants. In experiments testing the potential of this assay, wheat and barley (Hordeum vulgare L.) cultivars previously reported to have low NRA were less susceptible to chlorate‐induced toxicity than were cultivars reported to have high NRA. The assay was used to screen 15 soft red winter wheat cultivars for differences in sensitivity to chlorate‐induced toxicity. Variable toxic reactions were observed both among and within the cultivars. To determine whether the within‐cultivar variation was environmental or genetic, single plant selections for contrasting chlorate response were made, and bulked progeny were rescreened. In eight of 15 cultivars, the contrasting selections were different for chlorate‐induced toxic response, indicating heterogeneity for this trait within these eight cultivars. These chlorate‐selected lines may also be near‐isogenic lines for NRA. Seedling screening of wheat for chlorate response may be useful for identification of high NRA breeding lines.