铁毒胁迫对水稻产量性状的影响

利用温室水稻水培试验,研究了铁毒胁迫影响水稻产量性状的特征,并探讨了其与各部位铁含量和籽粒铁含量的关系。结果表明：铁毒胁迫显著抑制水稻的叶长、株高、分蘖数、穗数,同时降低了籽粒的粒长、粒宽,致使千粒重显著减少。铁毒胁迫下,大部分铁被阻隔在水稻根部,在地上部各部位中,老叶的铁含量增加最为明显,而新叶和成熟叶则无明显增加;水稻籽粒中的铁含量在铁毒胁迫下也显著上升。     

根表铁膜对元素吸收的效应及其影响因素

水生植物根系表面普遍形成铁膜,铁膜的形成是水生植物适应淹水和其他环境胁迫的重要机制之一.大量研究表明铁膜在植物吸收有益营养元素和有害元素中有重要作用.本文总结了植物根表铁膜形成的过程及铁膜的形态、组分、数量等特征,阐述了铁膜对植物吸收元素的效应.水生植物根表的铁膜能够阻止植物对金属元素的吸收,也可充当植物根系表面的养分\"库\",在植物需要养分时铁膜中的养分可以被活化并被植物吸收利用.此外铁膜的效应还与根表铁膜的数量有关,少量铁膜能够促进植物对养分的吸收,而大量铁膜则阻止植物对养分的吸收.造成铁膜不同效应的因素包括植物、重金属和研究采用的手段和技术等.如植物种类、品种、生育阶段以及营养状况、植物的培养方式、所研究的金属离子种类以及根表铁膜的分析技术等均可影响试验结果.进一步的研究工作需考虑铁膜形成的外部环境,利用原位技术以确定铁膜中元素的分布和化学形态,并将铁膜的效应与土壤植物的整体反应结合起来进行系统的研究.     

不同铁形态对水稻根表铁膜及铁吸收的影响

通过溶液培养试验研究了FeCl2?4H2O和FeCl3?6H2O对水稻根表铁膜数量及铁吸收的影响。结果表明,FeCl2处理时水稻根表铁膜浓度是FeCl3处理的197%～233%。利用EDTA-BPDS对铁膜形态分析看出,根表铁膜中Fe3+占85%～92%,Fe2+占8%～15%。水稻天优998根表铁膜数量显著高于培杂泰丰,其铁吸收是培杂泰丰的115%～138%。两种铁形态处理明显提高水稻的根系活力,其中,FeCl2处理时水稻根系活力增加24%～69%,FeCl3为16%～54%。FeCl2处理时水稻根系SOD、POD和CAT活性分别增加11%～32%、15%～30%和30%～31%,但FeCl3处理没有明显影响。上述结果表明一定浓度铁处理明显增加水稻根表铁浓度和铁吸收;与FeCl3处理相比,FeCl2处理能提高根系抗氧化酶活性,增加水稻的铁吸收和根表铁膜数量。     

硒对镉胁迫下水稻幼苗叶片元素含量的影响

采用溶液培养研究Se对Cd胁迫下水稻幼苗叶片叶绿素和几种元素含量的影响结果表明,单用Cd处理,高浓度Cd使水稻幼苗叶片Ca、Mg、Fe、Zn、Mn含量显著减少;单用0.10mg/L Se处理可显著增加叶片Fe、Zn、Mn含量。Se使较高浓度Cd(5.0~10.0mg/L)胁迫下水稻幼苗叶片Ca、Mg、Fe、Mn含量高于单用Cd处理,Se与Cd的互作效应影响叶片Ca、Mg、Fe、Zn、Mn含量。叶绿素a/b值不能作为水稻幼苗Cd毒害指标。     

磷对铝胁迫下荞麦元素吸收与运输的影响

以不同耐铝基因型江西养麦(耐性)和内蒙荞麦(敏感)为材料,采用土培法研究磷对铝胁迫下荞麦生长和Al,P等元素吸收、运输的影响.结果表明,铝胁迫下0.2 g/kg的磷能有效缓解铝毒对荞麦根长的抑制.培养30d后,0.4 g/kg磷处理能显著降低铝在荞麦根系和地上部的积累.铝胁迫下加磷可影响养麦体内Ca,Mg,Mn,Zn,Fe的吸收,0.4 g/kg铝配施0.4 g/kg磷处理对荞麦根系Ca,Mg吸收最有利,内蒙荞麦根系Mg的含量比不加磷组提高了76.8%,但显著阻碍了铝胁迫下荞麦体内Ca,Fe的向上运输.铝胁迫下配施磷促进荞麦根系对Zn,Fe吸收,有利于Zn向地上部转运.施磷能有效缓解铝毒对荞麦生长的抑制,降低根系和地上部铝含量,有利于Ca,Mg,Mn,Zn,Fe的吸收和Mg,Zn的运输.     

低钾胁迫对水稻苗期矿质营养吸收和植物激素含量的影响

以水稻（Oryza sativa L.）受体N27（对照）和来源于N27的耐低钾基因型水稻N18和N19为材料。采用溶液培养技术研究了低钾胁迫对其苗期矿质营养吸收和叶片植物激素含量的影响。结果表明,在低钾胁迫下,水稻幼苗吸钾效率和钾利用效率以及植株钾转运率降低,但N18、N19的降低幅度小于N27。同时,低钾胁迫下N18和N19与N27相比具有较强吸收和运输钠、磷、镁、铁和钙的能力。低钾胁迫使水稻叶片IAA、GA1和ZR的含量以及IAA/ABA、ZR/ABA和GA1/ABA比值均降低,N18、N19的降低幅度小于N27,且具有较高的IAA、GA1和ZR的含量以及IAA/ABA、ZR/ABA和GA1/ABA比值;低钾胁迫下N18、N19叶ABA的含量增加幅度小于N27。水稻耐低钾特性与其矿质营养吸收能力和植物激素水平或植物激素间比例关系有关。     

低钾胁迫下外源生长素对烟草根系生长及钾吸收的影响

【目的】探明生长素参与低钾胁迫下植株根系的生长发育及吸钾机制,同时为提高植物体内钾素水平提供理论依据。【方法】采用室内水培法,以模式植物烟草为试验材料,通过设置2个钾浓度(5、0.15 mmol/L)和5个外源生长素(3–吲哚乙酸)浓度(0、5、10、20、40μmol/L),对植物根系生理特征、内源生长素浓度、钾素累积及钾吸收动力学和相关钾离子通道基因转录表达进行比较研究。【结果】1)与正常钾水平相比,在低钾胁迫条件下,植株地上部干重显著降低15.6%;根系扫描8项指标中,除根平均直径外,其余7项指标值均显著降低;ATPase活性显著降低43.3%;主根尖、侧根尖及叶片内源生长素浓度显著升高;钾吸收动力学参数Vmax、Km值分别显著降低了89.2%、99.6%;植株根系、叶片钾浓度分别显著降低了93.0%、62.2%;根系中内流型钾离子通道基因Ntkc1的表达量显著降低56%。2)添加外源生长素后,正常供钾植株的根系干物质重、根系活力、主根尖及侧根尖内源生长素浓度有增加的趋势,Vmax值和内流型钾离子通道基因NKT2、NtKC1的表达量明显增加;低钾条件下,植株表现出和正常供钾相似的规律,除此之外,低钾植株的根系生长得到明显改善,ATPase活性和地上地下部钾素浓度明显增加,外流型钾离子通道基因Ntork1的表达量明显降低。3)当添加生长素浓度为10μmol/L时,与未添加生长素相比,正常供钾植株的地上地下部干重显著增加了6.05%、8.54%;根体积及根系交叠数显著增加16.5%、23.2%;根系活力显著增加了298%;Vmax值显著增加了118%;低钾植株地上地下部干重与不添加相比显著提高了5.61%、28.6%;根系活力达到113μg/(g·h), FW,为无添加生长素时的3.3倍;根系ATPase活性相对增加了87.5%;根系钾浓度显著增加250%;钾离子通道基因NKT2在根系中表达量显著增加了7.04倍,Ntork1在根系及叶片中表达量显著降低了49.5%、72.5%。【结论】低钾胁迫影响烟草根系生长及植株对钾素的吸收累积,添加适当浓度外源生长素可改善植株根系生长发育状况,增加内流型钾离子通道基因NKT2、NtKC1的表达量,降低外流型钾离子通道基因Ntork1的表达量,且提高植株钾吸收动力学参数Vmax值、降低Km值,从而提高了植株对钾离子的吸收能力与亲和力,进而增加植株钾素浓度。     

铝胁迫下外源抗坏血酸对水稻幼苗抗氧化性能的影响

为探讨外源抗坏血酸(AsA)对铝胁迫下水稻抗氧化损伤的效应,以滇优35号(杂交稻,粳稻)为试验材料,采用溶液培养法研究外源AsA对不同铝浓度(0、50、100、200、400μmol·L-1)胁迫下水稻根尖H202含量及抗氧化酶活性等生理生化指标的影响.结果 表明,水稻根尖氧化损伤程度随铝浓度的递增而加剧,与对照相比,...     

低钾胁迫下水稻钾高效基因型若干生长特性和营养特性的研究

采用溶液培养筛选,结合田间试验,提出了采用低钾胁迫下水稻体内钾利用效率作为衡量水稻钾利用效率的指标;探讨了钾高效基因型水稻的若干生长特性和营养特性;指出低钾胁迫导致水稻生物量减少,植株生长缓慢,分蘖能力差,根系生长受到抑制,根系吸收的钠增加。水稻钾高效基因型低钾胁迫下仍具有较强的生长势(相对干重、相对株高、相对根长较大),其地上部钾/钠比值高而根部钾/钠比值较低,地上部和根部钾/氮吸收量比值较低。     

水稻根表铁氧化物胶膜对水稻吸收磷的影响

本文采用营养液培养方法研究了根表铁氧化物胶膜对水稻吸收磷的影响。结果表明,水稻报表的铁氧化物胶膜随营养液中Fe2+浓度的增加而增加。铁氧化物胶膜可富集生长介质中的磷,根表铁膜数量越多,富集的磷量也越多。根表铁股可促进水稻对磷的吸收,但这种促进作用的大小依赖于根表铁膜数量。根表铁膜数量为24570mp／kg时,促进作用达到最大,此后随着铁膜数量的增加,水稻吸收磷的数量下降,但仍高于根表没有铁膜的水稻。因此,水稻根表形成的铁氧化物胶膜在一定程度上是一个磷富集库,对水稻吸收磷起促进作用。在此过程中,缺铁条件下水稻根分泌物中的植物铁载体对淀积铁氧化物胶膜的水稻根系吸收磷没有明显的作用。     

Effects of Exogenous Salicylic Acid and Nitric Oxide on Peanut Seedlings Growth under Iron Deficiency

Salicylic acid (SA) and nitric oxide (NO), which are known as important signaling molecules in plants, could be promising compounds for the reduction in stress sensitivity. The aim of the present work was to study the physiological changes in peanut (Arachis hypogaea L.) seedlings grown in growth medium that contained 0.1 mM SA, 0.25 mM sodium nitroprusside (SNP, a NO donor), or in full (SA+SNP) or half [1/2 (SA+SNP)] combined strengths under iron (Fe) deficiency. After 21 days of treatment, Fe deficiency significantly inhibited peanut plant growth, destroyed photosynthetic system, and caused oxidative damages. Addition of SA, SNP, and 1/2 (SA+SNP), especially SA+SNP, alleviated the stress, increased the contents of chlorophylls, and promoted plant growth. They improved Fe uptake, transport, and availability in peanut plants by increasing the activities of H⁺-ATPase and ferric chelate reductase (FCR), and promoting Fe translocation from cell wall to cell organelle and soluble fraction in leaves. Furthermore, they also effectively mitigated oxidative damages by increasing the activities of antioxidant enzymes in peanut leaves and roots. The results from the present study indicate that application of SA, SNP, or 1/2 (SA+SNP) can overcome the adverse effect of Fe deficiency, but the combined application of SA+SNP is more effective in alleviating Fe deficiency stress.     

Iron Toxicity in Wetland Rice and the Role of Other Nutrients

Abstract

Iron (Fe) toxicity is a widespread nutrient disorder of wetland rice grown on acid sulfate soils, Ultisols, and sandy soils with a low cation exchange capacity, moderate to high acidity, and active Fe (easily reducible Fe) and low to moderately high in organic matter. Iron toxicity reduces rice yields by 12–100%, depending on the Fe tolerance of the genotype, intensity of Fe toxicity stress, and soil fertility status. Iron toxicity can be reduced by using Fe-tolerant rice genotypes and through soil, water, and nutrient management practices. This article critically assesses the recent literature on Fe toxicity, with emphasis on the role of other plant nutrients, in the occurrence of and tolerance to Fe toxicity in lowland rice and puts this information in perspective for future research needs. The article emphasizes the need for research to provide knowledge that would be used for increasing rice production on Fe-toxic wetlands on a sustainable basis by integration of genetic tolerance to Fe toxicity with soil, water, and nutrient management.     

Calcium Effects on Acetic Acid Toxicity in Rice

Recent soil‐management practices such as no‐tillage and minimal tillage, when applied to the irrigated rice crop, promote changes in soil composition as a result of anaerobic degradation of organic matter. Several short‐chain organic acids are formed, such as acetic acid. The objective of this work was to determine the effect of calcium (Ca) on plant development under stress by acetic acid toxicity. The experiment was conducted in hydroponics by testing different Ca (0.2, 1.0, and 5.0 mmol L^?1) and acetic acid (0 and 2.5 mmol L^?1) concentrations. The variables evaluated were the root system morphological parameters (total length, radius, area, dry‐matter weight, and main root growth), shoot parameters (shoot dry matter, plant height), and concentration and total accumulated nitrogen (N), phosphorus (P), potassium (K), Ca, and magnesium (Mg) in the plants. The growth of the root system and the shoots of rice plants were not affected by the addition of Ca to the treatments containing acetic acid.     

Diagnosis and Amelioration of Iron Deficiency under Aerobic Rice

ABSTRACT

Iron (Fe) deficiency is one of the serious nutritional disorders in aerobically grown rice on upland alkaline and calcareous soils, which leads to a decline in productivity. With a view to resolve the Fe-deficiency syndrome in aerobic rice, the influence of soil moisture regimes, farmyard manure (FYM) and applied Fe on the release of Fe was assessed under an incubation study. A field experiment was also conducted to evaluate the relative effectiveness of soil and foliar applications of Fe in alleviating Fe deficiency using four rice cultivars (‘IR 36’, ‘IR 64’, ‘IR 71525-19-1-1’ and ‘CT 6510-24-1-2’). Results of incubation study indicated that the application of FYM marginally improved the diethylene triamine pentaacetic acid (DTPA)-Fe status of soil over control. However, application of iron sulfate (FeSO₄ · 7H₂O) at 14 mg Fe/kg with FYM released as much Fe as did the application of 27 mg Fe/kg as FeSO₄ 7H₂O alone. Comparatively higher amounts of Fe were released under water saturation than that under drier soil moisture regimes and the effect of incubation period in releasing Fe was pronounced only under water saturation.

Under field study, supplementation of Fe through integrated or inorganic source caused improvement in the DTPA and ammonium acetate (NH₄OAc) extractable Fe similar to that recorded under incubation. The foliar application of Fe (3% FeSO₄ 7H₂O solution, thrice at 40, 60, and 75 days after sowing of rice, i.e., 45 kg FeSO₄.7H₂O/ha) was most effective and economical in correcting Fe deficiency in aerobic rice, followed by soil application of 150 kg FeSO₄.7H₂O + 10 t FYM/ ha and 305 kg FeSO₄.7H₂O/ha. Among the rice cultivars, ‘CT 6510-24-1-2’ and ‘IR 71525-19-1-1’ performed better under aerobic condition compared to ‘IR 36’ and ‘IR 64’. Differential response of rice cultivars to applied Fe was not related to Fe-nutrition; rather it was apparently related with inherent ability of cultivars to grow under water-stress condition. Ferrous iron (Fe^II) content in rice plants proved to be a better index of Fe-nutrition status compared to total plant Fe and chemically extractable soil Fe. The Fe^II concentration of ≥ 37 mg kg^?1 in plants (on dry weight basis) appeared to be an adequate level at 60 days after sowing for direct seeded rice grown under upland aerobic condition.     

Distribution of Trace Elements in Tissues of Two Shrimp Species from Persian Gulf and Effects of Storage Temperature on Elements Transportation

This study is focussed on evaluation of temperature effectduring frozen storage on movement of trace elements in differenttissues (exoskeleton, carapace and abdominal muscle) of twocommercially important shrimp species (Penaeusmerguiensis and Metapenaues affinis). Moreoverrelationships between total length and sex of specimens with concentration of trace elements in selected tissues were assessed. Concentrations of Cd, Cr, Cu, Fe, Mn, Ni and Znin samples were determined by ICP-AES. Only in the case of Niand Zn sex related differences could be observed. With theexception of Cu, the trace metals distributed significantlydifferent between the tissues. The only significant differencesbetween species were found in bioaccumulation of Mn. Sizedependent relationship was observed only for Ni. Associationsbetween Mn and Fe were positively and highly significant in allthe cases. The levels of all the metals in muscle of the shrimpsfrom the studied region were comparable to other world areas. MeanCu and Zn levels in edible parts of M. affinis stored at–10 °C exceeded some existing guidelines, while the concentrations at –30 °C were somewhat lower than them.     

Research on the Threshold of Aluminum Toxicity and the Alleviation Effects of Exogenous Calcium,Phosphorus, and Nitrogen on the Growth of Chinese Fir Seedlings under Aluminum Stress

Chinese fir (Cunninghamia Lanceolata Lamb, Hook) is generally considered a superior timber in southern China and other areas in the world. In the past few decades, aluminum (Al) toxicity has become one of biggest stress factors in the production and growth of Chinese fir, although this species prefers an acidic environment. To date, the selection of indicator species for Al toxicity remains critical in the field, and Al toxicity has not been successfully treated by artificially controlling Chinese fir plantations. To assess the Al toxicity risk, the height of the dominant tree, the concentration of calcium (Ca²⁺)/Al³⁺ in soil solution, and the concentration of Ca²⁺?/?[Ca²⁺ + iron (Fe³⁺) + Al³⁺] in litter leached organic acids were introduced. The results indicated that eight plots had suffered Al toxicity. The threshold of Al toxicity was 37.53 mg kg^?1 in soil or 1.39 mmol L^?1 in soil solution, a pH of 4.15, a Ca²⁺?/?(Ca²⁺ + Fe³⁺ + Al³⁺) molar ratio of 0.487, and a Ca²⁺/Al³⁺ molar ratio of 1.599. The positive effects of exogenous nutrition (Ca, phosphorus [P], and nitrogen [N]) on the growth of Cunninghamia lanceolata seedlings was also studied in pot experiments based on results in the field. The cation nutrition can lead to detoxification, and the exogenous nutrition thresholds were Ca²⁺/?Al³⁺ ≥ 2.8, phosphorus (P)/?Al³⁺ ≥ 4.4, ammonium (NH₄ ^?)–nitrogen (N)?/?Al³⁺ ≥ 4.5. The data presented in this study are very helpful for the understanding of the degree of Al toxicity and have notable significance for the management of Chinese fir plantations.     

Improved Mass Screening of Tolerance to Iron Toxicity in Rice by Lowering Temperature of Culture Solution

Breeding for tolerance to iron (Fe) toxicity in rice (Oryza sativa L.) is hindered by lack of a suitable screening technique. In the culture solution methods used to date, a major difficulty has been maintaining an excess level of iron concentration in order to reveal toxicity symptoms. Experimental results showed that this problem was solved by lowering the solution temperature to around 20°C, at which leaf discoloration in susceptible cultivars became more pronounced. At 20°C Fe uptake was increased from a threshhold content of 300 mg/kg of dry weight of shoot for toxic symptom to more than 1000mg/kg in susceptible and in tolerant cultivars. Concentrations of other related minerals in the plant tissue, i.e., potassium (K) and phosphorus (P), were not affected by the low solution temperature itself but by Fe content, which can be inferred on the basis of their response curves to the excess Fe treatment. Using the proposed screening method makes it possible to obtain reproducible results in screening a large number of plants or breeding lines.     

铅胁迫对向日葵幼苗矿质元素吸收和积累的影响

以不同浓度铅胁迫的向日葵整株幼苗为试验材料,用火焰原子吸收光谱法测定3个不同基因型向日葵中大量元素(K、Ca、Na、Mg)和微量元素(Fe、Mn、Cu、Zn)的含量。结果表明:不同浓度铅胁迫下3个基因型植株中的矿质元素累积量有明显的不同。首先,相同浓度铅胁迫下不同基因型向日葵幼苗对矿质元素吸收和积累的表现不同;其次,不同浓度铅胁迫下相同基因型向日葵幼苗对矿质元素的吸收和积累存在显著的差异(Cu、Zn元素除外)。     

弱光照条件下有机碳营养对水稻生长的影响

在弱光条件下,研究了不含氮的有机碳(蔗糖、α-酮戊二酸、丙三醇)对水稻生物量积累及氮素代谢的影响。结果表明,在弱光条件下叶喷有机碳有促进水稻生长的作用,反映在生物量增长及相关氮代谢的生理参数上。不同的有机碳效果不同,三种有机碳中以α-酮戊二酸的效果最好。与喷清水处理相比,其生物量增幅高达33.12%,水溶性氮/全氮降幅达48.31%。试验表明,不含氮的有机碳营养显示了可克服弱光及碳不足对作物生长制约的效果。