玉米种子萌发过程中Na+、K+和Ca2+含量变化与耐盐性的关系

玉米耐盐品种登海9号和盐敏感品种浚单18在含0、50、100、150和200 mmol L^-1 NaCl的营养液中萌发生长, 采用等离子质谱分别测定其萌动种子种皮、胚、胚乳和幼苗根、根颈、叶中Na⁺、K⁺、Ca²⁺的含量。结果表明, 随着培养液中NaCl浓度的增加, 玉米体内Na⁺含量逐渐升高, 在幼苗中表现地下部(根和根颈)显著高于地上部(叶); 在萌动种子中, 胚中Na⁺积累量显著高于种皮和胚乳。根系积累Na⁺能力较强, 胚拒Na⁺能力较弱, 种皮具有一定的Na⁺累积能力。随NaCl浓度的增加, K⁺和Ca²⁺含量逐渐降低, 尤其是Ca²⁺含量急剧减少, 达38.4%~55.9%(登海9号)和65.6%~78.2%(浚单18)。玉米根、根颈、种皮的Na⁺积累能力、叶的拒Na+能力和幼苗选择吸收Ca²⁺的能力可能与品种耐盐性有关。     

番茄树无土栽培设施及配方施肥栽培技术研究

介绍了番茄树无土栽培设施,包括营养液池、栽培池、供液系统、回流系统、控制系统、支撑设施,同时对其营养液配方施肥及其栽培技术管理进行试验研究,结果表明：每千克水中大量元素含量为N-NO₃- 100mg、N- NH₄^＋92 mg、P-H₂PO₄- 30 mg、Ca^2＋240 mg、Mg^2＋26 mg、K^＋378 mg;微量元素含量为 Fe 30 mg、B 0.5 mg、Mn 0.5 mg、Zn 0.05 mg、Cu 0.02 mg、Mo 0.01 mg,PH值为6.2~6.5之间。     

水分供应和氮素形态对水稻一些水分生理特征的影响

为探明不同水分供应和氮素形态对水稻一些水分生理特征的影响,设正常水分及50 g L^-1 PEG模拟水分胁迫及3种不同NH₄⁺-N/NO₃^--N比例（75/25,50/50,25/75）的处理,测定了水稻叶片的NO₃^-、Ca²⁺和Mg²⁺含量,叶片浸出液电导率,叶片相对含水量,叶片水分临界饱和亏以及叶片水势。结果表明,在NH₄⁺-N/NO₃^--N比例较低时,模拟水分胁迫使广陵香粳水稻幼苗吸收更多的NO₃^--N。模拟水分胁迫条件下,水稻幼苗叶片浸出液电导率随NH₄⁺-N/NO₃^--N比例的降低呈下降趋势,且在NH₄⁺-N/NO₃^--N比例为25/75时,叶片浸出液电导率低于正常水分培养条件下的叶片浸出液电导率。而在正常水分培养条件下,水稻幼苗叶片浸出液电导率随NH₄⁺-N/NO₃^--N比例的降低呈上升趋势。水分胁迫使高NH₄⁺-N/NO₃^--N处理水稻叶片相对含水量降低、水分临界饱和亏上升,但对低NH₄⁺-N/NO₃^--N处理（25/75）水稻叶片相对含水量和水分临界饱和亏影响很小。同样,低NH₄⁺-N/NO₃^--N处理削弱了水分胁迫对水稻叶片水势的降低。总体上说,低NH₄⁺-N/NO₃^--N能减轻水分胁迫对水稻水分生理的不良影响。     

基肥配比和拔节期追氮对糯玉米淀粉糊化特性的影响

为明确糯玉米淀粉糊化特性在不同肥料处理下的变化, 从而改良淀粉的糊化特性, 以糯玉米品种苏玉糯4号为材料, 采用二因素裂区设计, 研究了不同基肥处理(纯N 75 kg hm^-2、纯N 75 kg hm^-2 + K₂O 70 kg hm^-2、纯N 75 kg hm^-2 + P₂O₅ 65 kg hm^-2和纯N 75 kg hm^-2 + P₂O₅ 65 kg hm^-2 + K₂O 70 kg hm^-2)和拔节期追氮(0、150和300 kg hm^-2)对糯玉米淀粉糊化特性的影响。结果表明, 和仅基施氮相比, 增施磷或(和)钾可显著降低峰值黏度和崩解值, 提高谷值黏度、终值黏度和回复值。随着拔节期追氮量的增加, 峰值黏度、谷值黏度、终值黏度逐渐升高, 回复值先升后降, 而崩解值在追施氮150 kg hm^-2和300 kg hm^-2时无显著差异, 但均大于不施追肥处理。峰值黏度与谷值黏度、终值黏度、崩解值极显著正相关(相关系数分别为0.80**、0.87**和0.75**), 糊化温度与峰值黏度、谷值黏度和终值黏度显著负相关(相关系数分别为-0.65*、-0.62*和-0.60*)。在适宜基肥的基础上, 增加拔节期追氮量, 可以改良淀粉的糊化特性。在不同肥料处理中, 基施氮或氮磷并拔节期追施纯氮300 kg hm^-2及平衡基施氮磷钾并拔节期追施纯氮150 kg hm^-2时, RVA谱特征值较为理想(峰值黏度最高且回复值较低)。     

小冰麦(Triticum aestivum -Agropyron intermedium)对盐胁迫和碱胁迫的生理响应

将两种中性盐（NaCl和Na₂SO₄）和两种碱性盐（NaHCO₃和Na₂CO₃）按摩尔质量比1∶1混合,在60~300 mmol L^-1盐浓度内模拟出5种强度的盐胁迫条件,在30~180 mmol L^-1盐浓度内模拟出6种强度的碱胁迫条件,并以此对小冰麦苗胁迫处理12 d。测定相对生长率（RGR）、含水量、丙二醛（MDA）、电解质外渗率、叶绿素、类胡萝卜素6项胁变指标和Na⁺、K⁺、脯氨酸、甜菜碱、有机酸5种溶质含量。结果表明,碱胁迫下小冰麦的各项胁变反应均明显大于盐胁迫下。在本试验条件下,小冰麦可耐受的最高盐胁迫浓度为300 mmol L^-1,而碱胁迫仅为150 mmol L^-1。碱胁迫造成小冰麦光合色素含量急剧下降,可能是其危害甚于盐胁迫的原因之一。碱胁迫下有机酸大量积累可能是小冰麦响应碱胁迫的特殊生理机制。试验结果证明盐、碱胁迫是两种性质不同的胁迫,不仅对植物的作用机制不同,而且植物的适应机制也不同。     

边缘细胞对大豆根尖铝毒害的缓解

以大豆[Glycine max (L.) Merrill]浙春3号为试验材料, 采用静置培养(保持边缘细胞附于根尖)和振荡培养(移除根尖边缘细胞), 测定边缘细胞数目和活性、根相对伸长率和根内酶的活性, 研究了边缘细胞对大豆根尖铝毒害的缓解效应。结果显示, 大豆发育过程中存活的边缘细胞数与总数之比达60%~80%, 50~400 mmol L^-1 Al³⁺胁迫12 h能诱导边缘细胞从根尖脱落, 200~400 μmol L^-1 Al³⁺胁迫24 h对边缘细胞的发育有抑制作用。Al³⁺处理抑制根伸长, 移除边缘细胞的根相对伸长率低于保留边缘细胞的根。0~100 mmol L^-1 Al³⁺胁迫12 h, 0和50 mmol L^-1Al³⁺胁迫24 h, 具有边缘细胞的大豆根系的POD、SOD活性及蛋白质含量显著高于移除边缘细胞的根内酶活性和蛋白质含量, 但200和400 mmol L^-1 Al³⁺处理12 h, 100~400 mmol L^-1 Al³⁺处理24 h时, 根尖有无边缘细胞对根系的酶活性及蛋白质含量影响不显著。说明低浓度Al³⁺胁迫下, 大豆通过增加边缘细胞数目、提高根尖蛋白质含量, 维持较高水平的POD、CAT和SOD活性来对抗铝毒胁迫, 以缓解植物的铝毒害。     

结实期氮磷营养水平对水稻根系分泌物的影响及其与稻米品质的关系

以扬稻6号（籼稻）和扬粳9538（粳稻）为材料,在水培条件下自抽穗至成熟期进行0 N（不施N）、1/2 N(标准Espino营养液的1/2 N)、0 P（不施P）、1/2 P(标准Espino营养液的1/2 P)以及对照（全NP,标准Espino营养液的N、P量）5种处理,研究了水稻根系分泌物的变化及其与稻米外观品质、蒸煮食味品质及蛋白质组分的关系。结果表明,与对照相比,结实期氮素胁迫（0 N）明显降低了水稻的根系活力,降低了各种有机酸、氨基酸及离子的分泌量,加速了根系的衰老;磷胁迫（0 P）显著增加了根系有机酸、氨基酸及各种离子的分泌。相关分析表明,结实前中期（花后10 d和20 d）根系分泌的酒石酸、柠檬酸和氨基酸与籽粒垩白度、直链淀粉、崩解值呈显著或极显著负相关,与淀粉谱的消减值呈极显著正相关;根系分泌的苹果酸与籽粒垩白度、直链淀粉、崩解值呈极显著正相关,与淀粉谱的消减值呈极显著负相关;根系分泌的[Ca²⁺]、[K⁺]、[Na⁺]、[NO₃^-]、[NH₄⁺]、[PO₄^3-]与稻米的垩白度、直链淀粉含量、蛋白质组分也显著或极显著相关。表明根系分泌物与稻米品质的形成有密切的关系,N、P营养水平对根系分泌物有调控作用,进而影响稻米品质。     

夏玉米光合特性对氮素用量的反应

随氮素用量增加,植株下位叶、穗位叶和上位叶的光合速率（P_n）、叶绿素含量（Chl）、可溶蛋白含量（Pro）、Hill反应活性、Ca²⁺-ATPase活性、Mg²⁺-ATPase活性和PEPCase活性均不断增大。植株不同叶位Pn和Pro随生长进程均不断下降;不同叶位Chl的变化动态表现为下位叶在各测定时期之间差异较小、穗位叶和上位叶为单峰曲线。Hill反应活力、Ca²⁺-ATPase活性和Mg²⁺-ATPase活性的变化规律不同,随生长进程表现不断下降、单峰曲线和双峰曲线等不同形式。各叶位PEPCase活性均表现单峰曲线型变化。随氮素用量增加,叶源量、生物产量和籽粒产量不断增加。适量施氮具有全面改善玉米光合效率和内在生理、生化过程的作用。Ca²⁺-ATPase活性是影响光反应活力的重要因素;在叶片生长前中期,P_n受到PEPCase的影响较小,主要受到光反应活力和暗反应效率的调控。可采用叶源量作为玉米单株生产力的参考诊断指标。     

AsA-GSH循环对水稻突变体耐汞性的作用

以水稻中花11及其汞耐性突变体的溶液培养, 研究了在0.4 mmol L^-1 Hg²⁺胁迫下汞耐性突变体的活性氧代谢及抗坏血酸-谷胱甘肽(AsA-GSH)循环的变化。结果表明, Hg²⁺胁迫下, 突变体叶片中的H₂O₂含量、产生速率和MDA含量、GSSG含量、DHA含量显著低于野生型; 突变体叶片中GSH/GSSG和AsA/DHA的比值均高于野生型, 同时突变体根和茎中的Hg²⁺含量明显高于野生型。说明汞耐性突变体体内AsA-GSH循环在Hg²⁺胁迫下仍能保持较高的运转效率和清除活性氧的能力, 在其耐汞性中起重要作用。     

紫花苜蓿Na+/H+ 逆向转运蛋白基因在拟南芥中表达提高转基因植株的耐盐性

以紫花苜蓿(Medicago sativa)为材料, 利用反转录PCR方法分离了NHX1全长cDNA(命名为MsNHX1)。Southern杂交结果表明, 在紫花苜蓿中存在一个小的液泡型Na⁺/H⁺逆向转运蛋白基因家族。序列分析表明, 该基因所编码的蛋白与拟南芥、水稻和棉花中液泡型Na⁺/H⁺逆向转运蛋白具有较高的同源性。在洋葱表皮细胞中瞬时表达MsNHX1-GFP融合基因的结果表明, MsNHX1定位在液泡膜上。Northern杂交发现该基因的表达受高浓度NaCl诱导。MsNHX1在盐敏感酵母突变体中表达可以提高转化子对NaCl的耐受性, 说明MsNHX1具有转运Na⁺的功能。在拟南芥中表达MsNHX1能显著提高植株耐受盐胁迫的能力; 而且在受到盐胁迫时, 转基因植株比野生型的渗透调节能力更强, 生物膜受破坏程度降低, 光合能力增强。以上研究结果表明MsNHX1是一个液泡膜Na⁺/H⁺逆向转运蛋白, 在植物耐受盐胁迫过程中起重要作用。     

燕麦对碱胁迫的阳离子响应机制

以耐碱性燕麦品种Vao-9和碱敏感性品种白燕5号为试验材料,采用盆栽法,用25、50、75、100 mmol L^-1碱浓度(Na₂CO₃和NaHCO₃按摩尔比1∶1混合)进行短期(14 d)和长期(28 d)胁迫处理,观测两品种根、茎、叶中Na⁺、K⁺、Ca²⁺、Mg²⁺吸收及分配特点,并从离子平衡吸收与分配角度,探讨燕麦对碱胁迫的生理适应机制。胁迫处理14 d后,燕麦体内Na⁺增加,K⁺下降,Ca²⁺和Mg²⁺变化不大,且两品种间各器官中4种离子的分配比例差异不显著。胁迫处理28 d后,两品种各器官中Na⁺增幅较大,K⁺、Ca²⁺和Mg²⁺降幅较大。Vao-9植株体内Na⁺、Ca²⁺含量大于白燕5号,但K⁺、Mg²⁺含量与白燕5号无显著差异,但两品种间各器官中4种离子的分配特点不同;当胁迫浓度达到100 mmol L^-1时,与白燕5号相比,Vao-9叶片中少分配5.9个百分点Na⁺,多分配13.5个百分点K⁺、28.9Ca²⁺、10.9Mg²⁺,茎中多分配5.4个百分点Na⁺,少分配9.8个百分点K⁺,根中少分配28.9个百分点Ca²⁺、10.9Mg²⁺,因而Vao-9叶片中Na⁺ /K⁺、Na⁺ /Ca²⁺、Na⁺ /Mg²⁺值较白燕5号低。可见,燕麦通过提高阳离子选择吸收及器官分配能力以适应碱胁迫。     

紫花苜蓿Na+/H+ 逆向转运蛋白基因在拟南芥中表达提高转基因植株的耐盐性

以紫花苜蓿(Medicago sativa)为材料, 利用反转录PCR方法分离了NHX1全长cDNA(命名为MsNHX1)。Southern杂交结果表明, 在紫花苜蓿中存在一个小的液泡型Na⁺/H⁺逆向转运蛋白基因家族。序列分析表明, 该基因所编码的蛋白与拟南芥、水稻和棉花中液泡型Na⁺/H⁺逆向转运蛋白具有较高的同源性。在洋葱表皮细胞中瞬时表达MsNHX1-GFP融合基因的结果表明, MsNHX1定位在液泡膜上。Northern杂交发现该基因的表达受高浓度NaCl诱导。MsNHX1在盐敏感酵母突变体中表达可以提高转化子对NaCl的耐受性, 说明MsNHX1具有转运Na⁺的功能。在拟南芥中表达MsNHX1能显著提高植株耐受盐胁迫的能力; 而且在受到盐胁迫时, 转基因植株比野生型的渗透调节能力更强, 生物膜受破坏程度降低, 光合能力增强。以上研究结果表明MsNHX1是一个液泡膜Na⁺/H⁺逆向转运蛋白, 在植物耐受盐胁迫过程中起重要作用。     

Physiological Responses of Krishum (Iris lactea Pall. var. chinensis Koidz) to Neutral and Alkaline Salts

The aims of this study were to compare the physiological responses of krishum (Iris lactea Pall. var. chinensis Koidz) to neutral and alkaline salt stress and identify and examine the mechanisms involved in plant response to salt treatments. In this study, biomass, ion accumulation (Na⁺, K⁺, Ca²⁺, Mg²⁺), organic solute (proline) concentration, rate of membrane electrolyte leakage (REL) and antioxidase activities including those of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and peroxidase (POD, EC 1.11.1.7) were investigated in krishum under different concentrations of NaCl, Na₂CO₃ and the mixture of the two salts in the same volume. All three treatments caused increases in Na⁺ concentration, proline content and REL and decreases in root Mg²⁺ and K⁺ content. Increased Ca²⁺ and antioxidase activities were observed at lower external Na⁺ concentrations. However, at higher external Na⁺ levels, decreased Ca²⁺ and antioxidase activities were detected. Alkaline salt resulted in more damage to krishum than neutral salt including lower SOD, POD and CAT activities and decreased proline content, relative to neutral salt. High Na⁺ and low K⁺ in krishum intensified ion toxicity under alkaline condition. Alkaline salt caused greater harm to plants than neutral salt, the primary reason of which might be the lower Ca²⁺ content in the plant under alkaline salt stress.     

Growth‐Related Changes in Subcellular Ion Patterns in Maize Leaves (Zea mays L.) under Salt Stress

Na⁺ accumulation in the leaf apoplast has been suggested to lead to dehydration, later wilting and finally, the death of the affected leaves. Our aim has been to evaluate whether the reduction in the plant growth of sensitive maize in response to salinity is correlated with higher amounts of Na⁺ and Cl^? concentrations in the leaf apoplast. Subcellular ion patterns in intact leaves were investigated by using deionised water infiltration. We found an increase in soluble Na⁺ and Cl^? concentrations of about 16‐ and 4‐fold, respectively, compared with the control. These concentrations characterized the apoplasts of expanding leaves that had entirely developed under salinity. Interestingly, the K⁺ concentration was significantly reduced by 64 % compared with its control in the symplast under salinity. Our finding of a significantly decreased Ca²⁺ concentration in shoots suggested a possible association of Ca²⁺ concentration with the reduction in leaf expansion under salinity. As the absolute increase in the apoplastic Na⁺ concentration during salt treatment was much lower compared with the increase in the symplastic Na⁺ concentration, salt treatment in maize appears not to result in osmotic stress imposed by a high apoplastic Na⁺ concentration as has been suggested for other plant species (Oertli hypothesis).     

盐胁迫条件下外源Ca2+对蚕豆气孔运动及质膜K+通道的调控

研究了Ca²⁺ 对NaCl胁迫下蚕豆气孔运动及质膜K+通道的影响。结果表明,100 mmol L^-1 NaCl可明显诱导气孔开放,该现象可被10 mmol L^-1 CaCl₂ 显著抑制。为探讨盐胁迫下Ca²⁺对K⁺和Na⁺跨膜运输的调控机制,我们利用膜片钳技术记录全细胞K⁺ 电流发现,在100 mmol L^-1 NaCl胁迫下,加入10 mmol L^-1 CaCl₂胞外处理,显著抑制质膜K+内向及外向通道电流,这种抑制可被1 mmol L^-1 La³⁺ (Ca²⁺通道抑制剂)缓解。非盐胁迫下,10 mmol L^-1 CaCl₂ 胞外处理也能显著抑制质膜内向K⁺通道,但明显激活其外向通道,加入1 mmol L^-1 La³⁺并不能被缓解。用H₂O₂专一的荧光探针二氯荧光素二乙酸酯(H2DCF-DA)单细胞分析保卫细胞内H₂O₂含量变化显示,在100 mmol L^-1 NaCl盐胁迫下,10 mmol L^-1 CaCl₂ 处理明显诱导H₂O₂在保卫细胞中积累;100 mmol L^-1 NaCl和10 mmol L^-1 CaCl₂单独处理并不能诱导H₂O₂积累。推测Ca²⁺在盐胁迫下可能先诱导H₂O₂在胞内积累,进而激活质膜Ca²⁺通道,迅速提高胞内Ca²⁺浓度以抑制Na⁺通过质膜K⁺通道跨膜内流,同时调节Na⁺外流,两种效应共同作用促使气孔关闭,减少盐胁迫下水分的过度散失。上述结果将为Ca²⁺调控作物抗盐机制研究提供新的思路。     

Genetic basis of physiological traits related to salt tolerance in tomato, Lycopersicon esculentum Mill.

Genetic relationships between salt tolerance and expression of various physiological traits during vegetative growth in tomato, Lycopersicon esculentum Mill., were investigated. Parental, F₁, F₂ and backcross progeny of a cross between a salt tolerant (PI174263) and a salt sensitive tomato cultivar (‘UCT5’) were evaluated in saline solutions with electrical conductivity of 0.5 (non-stress) and 20 dS/m (salt stress). Absolute growth, relative growth, tissue ion content, leaf solute potential and the rate of ethylene evolution were measured. Growth of both parents was reduced under salt stress; however, the reduction was significantly less in PI174263 than ‘UCT5’, suggesting greater salt tolerance of the former. Under salt stress, leaves of PI174263 accumulated significantly less Na⁺ and Cl^? and more Ca²⁺ than leaves of ‘UCT5’. Across parental and progeny generations, growth under salt stress was positively correlated with leaf Ca²⁺ content and negatively correlated with leaf Na⁺ content. In contrast, no correlation was observed between growth and either leaf solute potential or the rate of ethylene evolution under salt stress. Generation means analysis indicated that under salt stress both absolute and relative growth and the Na⁺ and Ca²⁺ accumulations in the leaf were genetically controlled with additivity being the major genetic component. The results indicated that the inherent genetic capabilities of PI174263 to maintain high tissue Ca²⁺ levels and to exclude Na⁺ from the shoot were essential features underlying its adaptation to salt stress and that these features were highly heritable. Thus, tissue ion concentration may be a useful selection criterion when breeding for improved salt tolerance of tomato using progeny derived from PI174263.     

Effect of Salinity Stress on Growth and Nutrient Composition of Three Soybean (Glycine max L. Merrill) Cultivars

Soil salinity is a major limitation to legume production in many areas of the world. The salinity sensitivity of soybean was studied to determine the effect of salinity on seed germination, shoot and root dry weights, and leaf mineral contents. Three soybean cultivars, Lee, Coquitt, and Clark 63, were planted in soils of different salinity levels. The electrical conductivity (EC) of the soils used in this experiment was 0.5 dS m^?1. The soil salinity treatments were 0.5, 2.5 4.5, 6.5 and 8.5 dS m^?1. Saline drainage water from a drainage canal with an EC of 15 dS m^?1 was used to treat the soil samples in order to obtain the desired salinity levels. Germination percentages were recorded 10 days after planting. Shoot and root dry weights of 45‐day‐old plants were measured. Nutrient concentrations for Na⁺, K⁺, Ca²⁺, Mg²⁺ and Cl^? were determined. Germination percentages were significantly reduced with increasing salinity levels. The cultivar Lee was less affected by salinity stress than Coquitt and Clark 63. At 8.5 dS m^?1 a significant reduction in plant height was found in all three cultivars. However, Lee plants were taller than plants of the other two cultivars. Salinity stress induced a significant increase in leaf sodium (Na⁺) and chloride (Cl^?) in all cultivars. However, the cultivar Lee maintained lower Na⁺ and Cl⁺ concentrations, a higher potassium (K⁺) concentration and a higher K⁺/Na⁺ ratio at higher salinity levels than Coquitt and Clark 63. Saline stress reduced the accumulation of K⁺, calcium (Ca²⁺) and magnesium (Mg²⁺) in the leaves of the cultivars studied. This study suggests that Lee is the most tolerant cultivar, and that there is a relationship between the salt tolerance of the cultivar and macronutrient accumulation in the leaves.     

A Comparison of Screening Criteria for Salt Tolerance in Wheat under Field and Controlled Environmental Conditions

Although many screening criteria have been suggested to distinguish between genotypes for their salt tolerance under controlled environmental conditions, there is a need to test these criteria in the field. Saline soils are often complex and, therefore, unlikely to show a simple relationship to controlled conditions. To address this deficit, different agronomic and physiological screening criteria for salt tolerance in wheat at different stages were examined under both field and controlled conditions. Four wheat genotypes differing in their salt‐tolerance levels were grown in salt‐affected soil at two different locations and also under greenhouse conditions. Dry weight and leaf area of the upper and lower two leaves of the main stem and total dry weight at Zadoks scale 47 were measured in plants grown under field conditions. The concentrations of Cl^?, Na⁺, K⁺ and Ca²⁺ in the upper and lower two leaves of the main stem at Zadoks scale 47 and different yield components were measured in plants grown under both conditions. Our results indicate that measurements derived from the upper two leaves of the main stem were generally more effective as screening criteria than those from the lower two leaves. Correlation coefficients between grain yield and either dry weight or leaf area of the upper two leaves of the main stem indicated that dry weight is inferior to leaf area as a screening criterion under field conditions. Number of sterile spikelets per plant performed well under both conditions, whereas the number of spikelets per plant and 1000‐grain weight failed to distinguish the differences of salt‐tolerance levels among genotypes accurately. Weight and number of grains per plant and number of fertile spikes per plant were poor criteria under controlled conditions, but effective under field conditions. The maintenance of low Cl^? and Na⁺ concentrations in the upper two leaves offered the best guide to salt tolerance under both conditions. Potassium concentration was a poor criterion compared with the selectivity of K⁺ over Na⁺, which was useful under both field and controlled conditions. Calcium concentration and Ca²⁺ over Na⁺ selectivity in the upper and/or lower two leaves of the main stem were also effective in ranking genotypes according to their salt tolerance under both field and controlled conditions. Therefore, we conclude that simple measurements of the upper two leaves of the main stem including a straightforward measurement of leaf area, visually estimating the number of sterile spikelets, and a quick, practical determination of Na⁺ and Ca²⁺ concentration constitute effective criteria to screen wheat genotypes for salt tolerance under both field and controlled conditions.     

水稻(Oryza sativa)新型液泡Na+/H+逆向转运蛋白基因的特征分析和表达

以拟南芥AtNHX1 cDNA 片段作为探针，筛查水稻盐胁迫植株叶片cDNA 文库，获得与AtNHX1同源的水稻新型液泡Na⁺/H⁺逆向转运蛋白基因（OsANT1）。序列分析表明，OsANT1 全长cDNA为2 178 bp，包括一个长度为1 608 bp的完整开放阅读框，编码535个氨基酸残基。在DNA水平上，OsANT1基因含有15个外显子和14个内含子，长度为4 835 bp。OsANT1含有12个跨膜域，系统进化树分析结果表明，与来自拟南芥、水稻、小麦、玉米、大麦、马蔺和芦苇等的Na⁺/H⁺逆向转运蛋白高度同源。盐胁迫条件下，OsANT1的表达具有盐分诱导特征，且随着胁迫的增大而增加。表明该基因可能在水稻抵御盐分胁迫的过程中具有一定作用。     

Screening sorghum genotypes for salinity tolerant biomass production

Genetic improvement of salt tolerance is of high importance due to the extent and the constant increase in salt affected areas. Sorghum [Sorghum bicolor (L.) Moench] has been considered relatively more salt tolerant than maize and has the potential as a grain and fodder crop for salt affected areas. One hundred sorghum genotypes were screened for salinity tolerance in pots containing Alfisol and initially irrigated with a 250-mM NaCl solution in a randomized block design with three replications. Subsequently 46 selected genotypes were assessed in a second trial to confirm their responses to salinity. Substantial variation in shoot biomass ratio was identified among the genotypes. The performance of genotypes was consistent across experiments. Seven salinity tolerant and ten salinity sensitive genotypes are reported. Relative shoot lengths of seedlings were genetically correlated to the shoot biomass ratios at all stages of sampling though the relationships were not close enough to use the trait as a selection criterion. In general, the whole-plant tolerance to salinity resulted in reduced shoot Na⁺ concentration. The K⁺/Na⁺ and Ca²⁺/Na⁺ ratios were also positively related to tolerance but with a lesser r ². Therefore, it is concluded that genotypic diversity exists for salt tolerance biomass production and that Na⁺ exclusion from the shoot may be a major mechanism involved in that tolerance.