镉胁迫下钙对镉在玉米细胞中分布及对叶绿体结构与酶活性的影响

采用溶液培养试验、亚细胞组分分级分离技术、透射电子显微镜观察及生化分析等方法研究钙对镉胁迫下玉米根、叶组织镉的亚细胞分布、叶绿体超微结构及叶片RuBP 羧化酶和PEP 羧化酶活性的影响。结果表明,与缺钙加镉处理比较,镉毒害下添加钙,玉米根、叶细胞器和细胞质Cd 组分均显著下降,相应Ca 组分则显著增加,而细胞壁Cd 、Ca 含量各处理间均十分接近;镉毒害下添加钙,维管束鞘细胞基质片层及叶肉细胞基粒和基粒片层排列较好,维管束鞘细胞嗜锇粒大为减少,叶片RuBP和PEP羧化酶活性显著增加。说明Ca 对于Cd 胁迫下玉米叶片正常结构与功能的保持具有十分重要的意义。     

锌在再力花体内的富集性及亚细胞分布和化学形态研究

为研究Zn在再力花(Thalia dealbata Fraser)体内的富集性及亚细胞分布和化学形态,依次设定0(CK)、0.075 mmol.L 1、0.250 mmol.L 1、0.500 mmol.L 1、1.000 mmol.L 1、2.000 mmol.L 16个Zn处理浓度,对再力花进行水培培养的胁迫试验。结果表明:再力花不能有效地将Zn运输到地上部,Zn主要积累在根部。在系列Zn浓度处理下,转运系数均<1,得出再力花并非超富集植物。在此基础上,采用差速离心技术和化学试剂逐步提取法,研究Zn在该植物根系中的亚细胞分布和化学形态。结果表明:低浓度[0(CK),0.075mmol.L 1,0.250 mmol.L 1]Zn处理下,Zn主要分布于再力花根部的细胞壁、细胞核及叶绿体中;Zn在再力花根部的存在形态主要是乙醇提取态,占50%以上,其次是氯化钠提取态。随着Zn处理浓度的提高(0.500 mmol.L 1,1.000 mmol.L 1,2.000 mmol.L 1),细胞溶质成为Zn的最主要分布位点,分别占31.15%、45.12%和56.44%,其次为细胞壁;乙醇提取态的比例有所下降,氯化钠提取态、水提取态的比例则随着处理浓度的提高而提高至30%以上,成为Zn在再力花根部的三大存在形态。     

不同pH和不同氮素形态对小麦根中钙分布的影响

利用电镜技术研究了不同pH(4.0和6.0)和氮形态(NH4+-N和NO3---N)对小麦根系超微结构及根中Ca2+分布的影响。结果表明,1)pH.4.0处理下细胞结构中Ca2+明显少于pH.6.0处理;2)低pH造成质壁分离;3)铵态氮源处理下细胞结构中Ca2+明显少于硝态氮源处理,尤其体现在细胞间质、细胞壁、细胞膜上;4)铵态氮源处理也会导致细胞出现质壁分离,细胞结构松散,胞质外流;低pH加重这些现象。     

细胞壁组分在红酵母RS1高耐铝中的作用研究

红酵母RS1是从酸性油茶土壤中分离到的一株高耐铝微生物,能够忍耐高达200 mmol/L以上的铝,前期研究表明RS1高耐铝能力与细胞壁有关,但是其具体机制还不清楚。因此,本文进一步研究了细胞壁组分在RS1高耐铝中的作用,以期为RS1高耐铝的具体机制提供新信息。结果表明,高于70 mmol/L的铝对RS1生长产生抑制作用,0~70 mmol/L铝处理后细胞壁主要组分甘露糖和葡聚糖含量都没有显著改变,而细胞壁磷含量在70 mmol/L铝处理后显著升高。在高铝处理时,糖蛋白抑制剂抗生素衣霉素(tunicamycin)极大加重RS1的铝毒害。由此说明,细胞壁多糖组分含量并不对RS1高耐铝起到主要作用,细胞壁结构修饰如细胞壁磷含量响应和细胞壁N连接的糖蛋白修饰在RS1高耐铝中可能起到一定作用。     

丛枝菌根真菌作用下桉树对铅的耐受机制研究

通过盆栽桉树幼苗实验,采用差速离心法和化学试剂逐步提取法,从Pb在桉树不同部位中的亚细胞分布和化学形态的角度,研究了桉树对Pb的耐受机制。结果表明Pb主要富集在桉树根部（65%-84%）,在根、茎和叶中主要分布在细胞壁组分,其次在可溶组分。接种丛枝菌根真菌（AMF）没有改变Pb在植物中亚细胞分布的格局,但在高Pb处理（200 mg/kg,400 mg/kg）时增大了根部细胞壁组分和叶片可溶组分的分配比例,说明AMF可以增强细胞壁滞留作用和液泡区隔化作用。随土壤中Pb浓度的增加,桉树根部Pb的乙醇提取态的分配比例逐渐减少,而醋酸提取态的分配比例逐渐增加,在高Pb处理时以醋酸提取态为主（40%）。高Pb处理时接种AMF,可以促使植物体内的Pb从活性较强的提取态向活性较弱的提取态转化。因此,根部固持作用、细胞壁滞留作用、液泡区隔化作用及弱活性结合态增加作用,是AMF作用下桉树耐Pb的主要机制。     

蜈蚣草的植物修复作用对土壤中砷总量及形态分布的影响研究

通过盆栽试验研究砷(As)的超富集植物蜈蚣草(Pteris vittata)对As污染土壤中As总量的吸收,及形态分布的影响。结果表明,蜈蚣草羽叶、叶柄和根系部对土壤中As的吸收量相差很大,蜈蚣草将吸收的88.2%的As转移至地上部。蜈蚣草对土壤中的As污染具有较好的修复效果,供试土壤中总As量降低了12.4%。同时研究结果显示,蜈蚣草的修复作用改变了土壤中As的赋存形态,残留态As的百分含量从97.41%降低到92.96%,而交换态、碳酸盐结合态、铁猛氧化态及有机结合态As的百分含量分别从0.10%、0.07%、1.28%和1.23%上升至0.15%、0.09%、1.73%和5.07%。     

Ca2+在磷酸盐营养诱导黄瓜幼叶系统抗病中的作用

黄瓜第 2叶喷施 75mmol/L K2HPO4 溶液以后 ,每天采取叶片 ,用去离子水、1mol/L氯化钠、2 %醋酸和 5%盐酸 4种浸提液连续提取不同形态的钙 ,其中水溶性钙和果胶酸钙的含量减少而磷酸钙含量明显上升 ,同时 ,叶片中相关的抗病酶活性也持续升高。用焦锑酸钙沉淀的电镜细胞化学方法研究了叶片内Ca2+定位分布的变化后发现 ,与对照比较 ,喷施K2HPO4处理 ,液泡和叶绿体出现大量的钙颗粒分布 ,同时细胞间层中的钙沉淀也变得更为密集。用X 射线能谱仪测得细胞壁上Ca/P明显下降。上述现象表明 ,叶片细胞液泡和叶绿体含钙量增加以及磷酸钙沉淀的形成使得中间层的钙桥键断裂 ,从而引起抗病酶的产生 ,并导致细胞壁分解形成寡聚半乳糖醛酸 ,可诱导黄瓜苗产生系统抗病能力     

喷施钙对肥城桃果活性钙含量及其在亚细胞分布的影响

【目的】肥城桃是山东特产,但经常发生缝合线褐变、 不耐储藏等问题,补充钙肥是减轻其生理病害的有效措施。了解肥城桃的需钙规律,为肥城桃补充钙素营养提供理论依据和技术指导。【方法】以11年生红里肥桃为试材,从花后一个月开始,每隔30 d在选取的肥桃果树上喷施钙肥。试验设3个处理: 1)喷施0.5%氨基酸钙溶液; 2)喷施0.5%硝酸钙; 3)喷施清水为对照。从4月28日起每隔30 d采样,测定果皮、 果肉、 果核、 果仁总钙含量及果肉钙组分含量,在成熟期取果实用透射电镜观察果肉细胞内钙的亚细胞分布。【结果】3个处理果实中的钙含量均以幼果期最高,随着果实的成熟,全钙、 水溶性钙、 果胶酸钙含量均呈下降趋势,喷钙处理在一定程度上提高了果皮、 果肉、 果核及果仁的总钙含量,其中果肉总钙含量变化最明显,在果实成熟期,喷施氨基酸钙及硝酸钙的处理果肉总钙含量分别增加了68%、 77%。通过电镜观察,喷钙果肉细胞中钙均匀分布于细胞壁、 细胞膜、 液泡膜上,液泡中有钙的堆积; 未喷钙细胞壁中钙的分布减少,细胞膜、 液泡膜上钙也均匀分布; 发生褐变的果肉细胞内钙分布很少且不均匀。【结论】肥城桃果实中全钙含量随着果实生长而迅速下降。喷施钙肥能提高果实全钙尤其是水溶性钙及果胶钙的含量,增加细胞壁钙的分布,有利于缓解果实发育过程中钙含量的下降。喷施氨基酸钙和硝酸钙都能增加肥城桃果肉的不溶性果胶含量,提高果实硬度。     

花生荚果钙素吸收机制研究

采用45Ca微观放射自显影、电子探针及特异性抑制剂研究花生荚果钙素吸收机制,结果表明,Ca2+是通过主动吸收由外界进入细胞质中,并以共质体途径在组织和细胞间运输,外果皮的周皮层和中果皮的纤维细胞层对Ca2+质外体运输有一定阻碍作用。钙通道抑制剂与ATP酶特异性抑制剂处理,中果皮和内果皮的薄壁细胞内未见45Ca显影,大量45Ca出现在周皮层,仅微量的45Ca到达中果皮细胞间隙和纤维细胞层质外体空间。电子探针的结果也可看出高钙峰出现在周皮层,而对照处理荚果整个组织的共质体和质外体均有45a的显影,且由外果皮向内,组织中的钙呈逆浓度梯度分布。2,4二硝基酸可抑制荚果钙素吸收速率,其抑制率达7092％。荚果钙素吸收动力学的结果表明,当Ca2+浓度为0-0.5mmol/L时,其吸收速率符合Michaelis-Menten酶动力学模型,Km值为0.0135mmol/L,Fmax为13210-4.mol/(cm2h);而当Ca2+浓度为1-5mmol/L范围时,其表现出复杂的吸收特征,此时Km和Fmax均无法得出明确的数值;供钙浓度为0.5-2.0mmol/L时,荚果干重及果仁干重与吸钙量均可达到最大并趋于稳定。     

冰核细菌对低温胁迫下枇杷幼果中果肉超微结构的影响

以“早钟6 号”枇杷幼果为试材, 采用人工降温的方法, 观察接种冰核细菌后, 果肉细胞超微结构在冻害胁迫下的变化过程。结果显示: 冰核细菌不同程度地加重了冻害胁迫对枇杷果肉细胞壁、叶绿体和线粒体的破坏程度; 冰核细菌对叶绿体的破坏最明显, 其次是细胞壁、线粒体; 冰核细菌使叶绿体在-1 ℃发生胞内结冰导致细胞冻害, 而未感染冰核细菌的叶绿体则发生胞间结冰, 冻害类型不同; 与-1 ℃低温相比, -3 ℃低温条件下冰核细菌的破坏作用更强。表明冰核细菌的存在加重了低温对细胞的伤害。     

Effect of calcium/potassium ratio ammonium supply on nutrition and yields of cucumber plants

A greenhouse experiment was conducted in order to study the influence of two calcium/potassium (Ca/K) ratios (0.75 and 0.33) and ammonium supply (0 and 1 mmol/L) in the nutrient solution on nutrient uptake, mineral composition, and productivity of cucumber plants grown in sand culture. There were not significant differences in nitrate consumption between the four treatments. Calcium and potassium consumptions were directly related with the Ca/K ratio in the nutrient solution. The treatment with Ca/K = 0.75 and ammonium supply, that showed the lowest potassium and nitrogen plant levels and the highest calcium uptake and concentration in plant, offered the highest yields.     

The effect of Mg: Ca ratio and osmotic potential of nutrient solutions on calcium transport into emergent leaves of the strawberry plant cv. Cambridge favourite

Strawberry plants, cv. Cambridge Favourite were grown at osmotic potentials of ‐0.2 and ‐0.8 bars in nutrient solutions with magnesium : calcium ratios ranging from 0.3 to 5.6: 1. When the OP was ‐0.8 bars, all plants showed leaf tipburn, guttated little, yielded small volumes of exudate overnight from cut stolons and had small calcium concentrations and contents in their emergent leaves, regardless of the Mg: Ca ratio of the nutrient. No symptoms were seen in plants grown at an OP of ‐0.2 bars, although the calcium concentration in the emergent leaves was smaller when the Mg: Ca ratio of the nutrient exceeded 0.8: 1. The overall salt concentration, which reduced the water potential gradient through the root and prevented development of root pressure at night, was more important than the magnesium to calcium balance of the nutrient solution in causing a local calcium deficiency in emergent leaves of the strawberry plant.     

Effects of NaCl and Supplementary Potassium on Gas Exchange,Ionic Content,and Growth of Salt-Stressed Strawberry Plants

Strawberry cultivar ‘Selva’ was grown in a hydroponic culture in a heated greenhouse to study the effects of supplementary potassium (K) added to nutrient solution and applied to the plants grown at high sodium chloride (35 mmol/L) concentration. Treatments were: (1) nutrient solution alone (N); (2) N + sodium chloride (NaCl) (35 mmol/L) (NS); (3) N + NaCl + potassium sulfate (K₂SO₄; 5 mmol/L) (NSK1); (4) N + NaCl + K₂SO₄ (10 mmol/L) (NSK2). Leaf area, biomass production, and gas exchange variables (Pn, E, gs, Ci) negatively affected by salinity. In addition, ionic concentrations (sodium, chlorine, and potassium) increased by salinity treatments. Supplementary potassium had positive effects to ameliorate the harmful effects of NaCl on leaf area. Shoot growing was decreased by potassium (K) application. Ionic concentrations of this cultivar show contradictory results. Although supplementary potassium increased K accumulation, but sodium (Na) and chlorine (Cl) concentrations of plant parts was increased. These results show that potassium can be applied for this cultivar in salinity conditions.     

施用钼肥对酸性黄棕壤上冬小麦叶片膜脂肪酸及叶细胞超微结构的影响

采用盆栽试验并通过电子显微观察,研究了施用钼肥对分蘖末期冬小麦叶片膜脂肪酸及叶细胞超微结构的影响。结果表明,施钼后冬小麦叶片膜脂肪酸组成以亚麻酸为主,膜脂不饱和度增大,细胞器和膜结构比缺钼完整;缺钼植株膜结构的稳定性差并导致植株抗寒力降低是细胞出现冻害的最本质原因。     

Two cultivars of peanut (Arachis hypogaea) seedlings show different tolerance to calcium deficiency

The objectives were to determine whether two peanut cultivars show different tolerance to calcium (Ca) deficiency. The seedlings of cultivars LH11 and YZ9102 at first trifoliate leaf stage were transplanted in nutrient solution for 28 days with 0.01 and 2.0 mmol/L Ca treatments. Low Ca supply did not affect plant growth, root length and surface area of YZ9102, whereas decreased plant biomass, root length and surface area of LH11 seedlings that appeared necrosis in shoot tip. YZ9102 plant had higher Ca concentration and more Ca distribution to leaves than LH11. Under limited Ca condition, LH11 appeared net Ca²⁺ effluxes in the zones of 0.2 ～ 1.5 mm from root apex, while YZ9102 roots maintained net Ca²⁺ influxes. Peanut cultivar YZ9102 seedlings had longer roots and higher capacities of Ca uptake and Ca translocation to shoots than LH11, which might be account for higher tolerance to Ca deficiency compared with LH11.     

不同浓度的NO_3~-对黄瓜幼苗光合特性的影响

水培条件下,不同浓度的NO_3~-处理黄瓜幼苗7d.测定了黄瓜幼苗光合速率及相关参数的变化,揭示了黄瓜幼苗光合作用功能对高浓度NO_3~-胁迫响应机理。结果表明.营养液中NO_3~-浓度在较低范围(14～98 mmol/L)内时,适当增加NO_3~-有利于净光合速率的提高,光饱和点的升高,羧化效率增大,淀粉粒增加,叶面积增加,有利于黄瓜幼苗光合物质的积累及植株的生长;营养液中NO_3~-浓度进一步增加(>98 mmoL/L)时,黄瓜幼苗叶绿素的含量降低,净光合速率显著降低,光饱和点、羧化效率均降低;182 mmoL/L NO_3~-的处理,叶绿体的结构受到损伤,基粒数、基粒片层数、淀粉粒均减少,且淀粉粒变小,干重和叶面积均降低。所以,NO_3~-浓度过高时,黄瓜幼苗利用强光、弱光、CO_2的能力减弱,叶肉细胞被损伤,非气孔限制造成光合速率降低,不利于黄瓜幼苗的生长。     

钙水平对大葱生长及氮代谢的影响

【目的】 通过探讨钙对大葱生长及氮代谢的影响,明确钙在提高大葱产量和品质中的作用,为优化大葱施肥技术提供理论依据。 【方法】 以‘昭和’和‘章丘’大葱为试材,进行了砂培试验和田间试验。用砂培试验营养液钙水平设 0、4、6、8 mmol/L 4 个处理。于大葱越夏期 (7 月 17 日)、叶丛速生期 (9 月 11 日) 及假茎充实期 (10 月 20 日)取大葱叶片测定不同形态氮含量以及硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合酶(GOGAT)和谷氨酸脱氢酶(GDH)活性,于收获期 (11 月 13 日) 测定大葱生长量、产量及品质。田间试验设置 0、225、450、675 kg/hm2 4 个水平 (以 CaO 计),于收获期 (11 月 13 日) 测定产量。 【结果】 砂培大葱株高、茎粗、根及茎叶鲜重均随营养液钙水平提高而显著增加,至钙水平达 6 mmol/L 时表现较好,单株生长量达 211.13 g,钙水平继续增加至 8 mmol/L 时,单株生长量仅 185.83 g,与 4 mmol/L 的 183.29 g 无显著差异;除根系鲜重外,‘章丘’大葱株高、茎粗及茎叶鲜重均显著高于‘昭和’大葱。适量增加钙水平亦可显著提高大葱叶片 GOGAT、GDH、NR、GS 活性,以叶丛速生期影响最大。大葱叶片铵态氮(NH₄+-N)、硝态氮 (NO₃--N)、可溶性蛋白、游离氨基酸含量均随营养液钙水平提高而呈先增加后降低,均以叶丛速生期最高。两品种大葱品质相关指标均以钙水平 6 mmol/L 时最高,8 mmol/L 时有所降低。钙水平为 6 mmol/L 时,盆栽大葱产量显著高于其它处理,‘章丘’和‘昭和’分别较对照增产 79.94% 和 74.42%。大田试验,‘章丘’和‘昭和’大葱均以施用 CaO 450 kg/hm2 产量最高,分别较对照提高 12.30%、19.00%。 【结论】 适量施钙可显著促进大葱生长,提高叶片氮代谢酶活性及不同形态氮含量,提高产量及品质。综合分析表明,以营养液钙水平 6 mmol/L、土壤施钙 450 kg/hm2 时最有利于大葱的生长及产量品质的提高。      

Arsenic uptake,distribution, and accumulation in tomato plants: Effect of arsenite on plant growth and yield

The response of tomato (Lycopersicum esculentum Mill, cultivar Marmande) plants to different levels of arsenic (As) in nutrient solution was investigated—the processes of uptake, distribution and accumulation of As, and the effect of arsenite on yield and plant growth (plant height, diameter of stem, stem and root length, fresh and dry weight of root, stems, leaves, and fruit). The experiment was performed at three levels of As: 2, 5 and 10 mg/L [added as sodium arsenite (NaAsO₂)] in a nutrient solution, together with the corresponding control plants. Arsenic uptake depended on the As concentration in solution and As content in the roots increased as the time of treatment increased. The most important finding was the high toxicity of arsenite to roots. The concentration in stems, leaves, and fruit was correlated with the As level in the nutrient solution. Although the As level of 10 mg/L damaged the root membranes, resulting in a significant decrease in the upward transport of As. Arsenic exposure resulted in a drastic decrease in plant growth parameters (e.g., maximum decrease of 76.8% in leaf fresh weight) and in tomato fruit yield (maximum reduction of 79.6%). However, it is important to note that the As concentration in the fruits was not toxic or harmful for human consumption.     

Effect of lowering nutrient solution concentration at night on leaf calcium levels and the incidence of tipburn in lettuce (Var. Gloria)

Butterhead lettuce (var. Gloria) were grown in an evaporatively cooled glasshouse using the nutrient film technique (NFT). During the day all plants received a complete nutrient solution (EC 2 dS/m). Treatments were imposed at night and included: complete nutrient solution (control); tap water (EC 0.19 dS/m); and calcium nitrate solutions containing either 100 mg Ca/L (EC 0.80 dS/m), or 200 mg Ca/L (EC 1.45 dS/m).

Tipburn occurred in the control and its incidence was reduced by the other treatments. This effect was associated with an increase in the concentration of calcium in new leaves, except in the water treatment. The night treatments did not affect the fresh weight of mature lettuce.

Circulation of either water or calcium nitrate (100 mg Ca/L) at night may, therefore, be a commercially acceptable means of reducing tipburn losses in lettuce crops grown using hydroponics.     

Growth and Ca,Mg, K,and P uptake by triticale,wheat, and rye at four al levels

This study was conducted to determine relationships between Al toxicity and mineral uptake of triticale (X Triticosecale, Wittmack), wheat (Triticum aestivum L.), and rye (Secale cereale L.). Two culti‐vars of each species were grown in 1/5‐strength Steinberg solution with 0, 3, 6, or 12 ppm Al added. The solutions were adjusted to pH 4.8 at transplanting and were not adjusted thereafter. The plants were grown in a growth chamber for 19 days before harvesting to determine nutrient solution pH, dry weights, and Al, Ca, Mg, K, and P levels in plants. Increasing Al concentration reduced the final pH of solutions. The addition of 12 ppm Al severely reduced the growth and increased Al concentration of plant tops. The Al levels in roots generally increased with increments of added Al up to 6 ppm. Increasing Al decreased the uptake of Ca, Mg, and P by plant tops more than that of K. Regression analyses indicated that Al toxicity was associated with increasing K/Ca + Mg equivalent ratios and decreasing P concentration in plant tops. Differences between species were: higher Al concentration in rye than wheat with 6 and 12 ppm Al, higher translocation of Ca from roots to tops in wheat than in rye and Mg in triticale and wheat than rye; K/Ca + Mg equivalent ratios associated with 50% reduction in top growth followed the order: triticales > tolerant wheat > sensitive wheat > rye. Differences in mineral uptake associated with Al toxicity in wheat were more indicative of differential Al sensitivity in wheat than in triticale and rye which have higher internal Al tolerance.