Nucleus-Encoded Thylakoid Protein,OsY3IP1,Confers Enhanced Tolerance to Saline and Alkaline Stresses in Rice

Abiotic stress confers serious damage to the photosynthetic machinery,often resulting in plant growth inhibition.Hypothetical chloroplast open reading frame 3(Ycf3)-interacting protein 1(Y3IP1)is a nucleus-encoded thylakoid protein and plays an essential role in the assembly of photosystem I.The full-length cDNA over-expresser(FOX)gene-hunting system is an approach using systemically generated gain-of-function mutants.Among the FOX-rice lines,a line CE175 overexpressing rice Y3IP1gene(Os Y3IP1)displayed less inhibition of root growth under saline(NaCl)stress.The expression of Os Y3IP1 was up-regulated under saline and alkaline(Na2CO3)stresses in the rice variety Kitaake.After saline and alkaline treatments,transgenic Kitaake overexpressing OsY3IP1-GFP(OsY3IP1-GFPox/Kit)displayed higher levels of chlorophyll content compared to Kitaake.Under the stress conditions,the maximum quantum yield of photosystem II photochemistry levels was higher in OsY3IP1-GFPox/Kit than in Kitaake.The increased tolerance conferred by OsY3IP1 overexpression correlated with reduced reactive oxygen species accumulation.Our data provide new insights into the possible role of OsY3IP1 in the pathway suppressing photooxidative damage under stress conditions.These features can be further exploited to improve saline and alkaline tolerances of rice plants in future.

RNAi-mediated suppression of the abscisic acid catabolism gene Os ABA8ox1 increases abscisic acid content and tolerance to saline–alkaline stress in rice(Oryza sativa L.)

Saline–alkaline(SA) stress is characterized by high salinity and high alkalinity(high p H), which severely inhibit plant growth and cause huge losses in crop yields worldwide. Here we show that a moderate elevation of endogenous abscisic acid(ABA) levels by RNAi-mediated suppression of Os ABA8 ox1(Os ABA8 ox1-kd), a key ABA catabolic gene, significantly increased tolerance to SA stress in rice plants. We produced Os ABA8 ox1-kd lines in two different japonica cultivars, Dongdao 4 and Nipponbare. Compared with nontransgenic control plants(WT), the Os ABA8 ox1-kd seedlings accumulated 25.9%–55.7% higher levels of endogenous ABA and exhibited reduced plasmalemma injury, ROS accumulation and Na;/K;ratio, and higher survival rates, under hydroponic alkaline conditions simulated by 10, 15, and 20 mmol L-1 of Na;CO;. In pot trials using SA field soils of different alkali levels(p H 7.59, 8.86, and 9.29), Os ABA8 ox1–kd plants showed markedly higher seedling survival rates and more vigorous plant growth, resulting in significantly higher yield components including panicle number(85.7%–128.6%), spikelets per panicle(36.9%–61.9%), branches(153.9%–236.7%), 1000–kernel weight(20.0%–28.6%), and percentage of filled spikelets(96.6%–1340.8%) at harvest time. Under severe SA soil conditions(p H = 9.29, EC = 834.4 μS cm-1),Os ABA8 ox1-kd lines showed an 194.5%–1090.8% increase in grain yield per plant relative to WT plants.These results suggest that suppression of Os ABA8 ox1 to increase endogenous ABA levels provides a new molecular approach for improving rice yield in SA paddies.

Screening of Rice Accessions for Tolerance to Drought and Salt Stress Using Morphological and Physiological Parameters

Drought and salinity are the most widespread soil problems, posing a big threat to food security in rice growing regions. The present study evaluated the performance of eleven rice genotypes using morphological and physiological parameters, under induced drought and salinity conditions. The seedlings were raised in 5 kg of homogenous soil in plastic bags in the greenhouse. For the drought experiment, each bag was watered with 200 ml of water twice daily until plants reached the five-leaf stage when watering was suspended for 2 weeks for the drought stressed plants but not suspended for the control plants. The experiment was a 2 × 11 factorial and the set up was arranged using the completely randomized design with three replications. Data were taken on Plant height, Number of tillers, leaf length, Number of green leaves, Number of dead leaves, Leaf rolling score (LRS) and Rate of water loss. The salinity experiment was set up in a similar manner except that the plants were irrigated twice a day for 2 weeks with 200 ml of treatment solution containing either 0 mM NaCl or 75 mM and data were collected on plant height, number of tillers, shoot fresh weight, shoot dry weight, Na+ and K+ concentrations, relative water content and chlorophyll content. Data from both experiments were subjected to Analysis of variance test using the GenStat software 10th edition and the means separated using least significant difference test. Individual stress response index (ISRI) was calculated for each parameter and the means used in grouping the varieties. Of the genotypes evaluated, four (FARO 44, NERICA 2, NERICA 8 and NERICA 5) were identified as tolerant, two (NERICA 4 and FARO 57) as moderately tolerant, while the rest were found to be sensitive to drought. Equally, two varieties (FARO 44 and RAM 137) stood out in the salinity screening as tolerant varieties, five were moderately tolerant while four (FARO 64, FARO 52, NERICA 2 and FARO 55) were clearly susceptible. FARO 44 is the only genotype that showed tolerance to both drought and salinity. The identified drought and salinity tolerant rice genotypes from this study can be recommended as genetic sources for future breeding programs for drought and salinity tolerance in rice.

Comparative Effects of Salt Stress and Extreme pH Stress Combined on Glycinebetaine Accumulation,Photosynthetic Abilities and Growth Characters of Two Rice Genotypes

Glycinebetaine （Glybet） accumulation, photosynthetic efficiency and growth performance in indica rice cultivated under salt stress and extreme pH stress were investigated. Betaine aldehyde dehydrogenase （BADH） activity and Glybet accumulation in the seedlings of salt-tolerant and salt-sensitive rice varieties grown under saline and acidic conditions peaked after treatment for 72 h and 96 h, respectively, and were higher than those grown under neutral pH and alkaline salt stress. A positive correlation was found between BADH activity and Glybet content in both salt-tolerant （P=0.71） and salt-sensitive （P=0.86） genotypes. The chlorophyll a, chlorophyll b, total chlorophyll and total carotenoids contents in the stressed seedlings significantly decreased under both acidic and alkaline stresses, especially in the salt-sensitive genotype. Similarly, the maximum quantum yield of PSII （Fv/Fm）, photon yield of PSII （ФPSII）, non-photochemical quenching （NPQ） and net photosynthetic rate （Pn） in the stressed seedlings were inhibited, leading to overall growth reduction. The positive correlations between chlorophyll a content and Fv/Fm, total chlorophyll content and ФPSII, and Pn as well as Pn and leaf area in both salt-tolerant and salt-sensitive genotypes were found. Saline acidic and saline alkaline soils may play a key role affecting vegetative growth prior to the reproductive stage in rice plants.

Research progress on plant tolerance to soil salinity and alkalinity in sorghum

Sorghum is an important source of food, feed and raw material for brewing, and is expected to be a promising bioenergy crop. Sorghum is well known for its strong resistance to abiotic stress and wide adaptability, and salt tolerance is one of its main characteristics. Increasing sorghum planting acreage on saline-alkalien land is one way to effectively use this kind of marginal soil. In this paper, domestic and overseas research on plant tolerance to soil salinity and alkalinity in sorghum, including salt-tolerant genetics and breeding, physiology, cultivation, and identification of tolerant germplasms, are reviewed. Suggestions for further studies on salinity and alkalinity tolerance in sorghum are given, and the prospects for sorghum production in saline-alkalien land are discussed.

Selection of Maize Genotypes with Tolerance to Osmotic Stress Associated with Salinity

Thirteen different inbred lines in relation to the type of grain and life cycles were characterized by testing for osmotic stress associated with salinity. The identification of tolerant genotypes would be an effective strategy to overcome the saline stress. Osmotic stress reduces immediately the expansion of the roots and young leaves which determine a reduction in the size of the plant. A completely randomized design was adopted to test seedlings under controlled conditions of light and temperature. Two treatments were used: 0 mM NaCl (as control) and 100 mM NaCl. After 15 days of complete salinization, the seedlings were harvested and several morphological traits were measured. The morphological traits of growth were leaf growth (Ar1, Ar2, Ar3 and Ar4), dry masses of shoot and root (SDM and RDM, respectively). Also, traits associated with water economy were registered: leaf water loss (LWL) and relative water content (RWC). The morphological traits were expressed in relative terms, while the traits associated with the economy of water were expressed in absolute terms. Uni and multivariate techniques were applied to identify genotypes with divergent behaviors to osmotic stress tolerance. Also, a Tolerance Index was employed to identify superior genotypes. Four clusters were obtained after applying a Cluster Analysis and Principal Component Analysis (PCA). The genotypes were compared to each other with a test of DMS. The results obtained with different statistical techniques converged. Some variables presented a differential weight classification of genotypes. The morphological traits like RDM, SDM, Ar3, Ar4 and Ar5 were the most discriminating. Tolerance Index allowed to classify genotypes, thus SC2 and AD3 lines were that reached highest value of the index and therefore would be tolerant lines, while AF3 and LP3 had a low index and were seen as sensible.

Effects of acute salinity stress on the survival and prophenoloxidase system of Exopalaemon carinicauda

The ridgetail white prawn Exopalaemon carinicauda is a euryhaline shrimp species in the estuarine and coastal areas of China.In this study,survival rates,transcription levels of two prophenoloxidase system-related genes(Ec LGBP and Ecpro PO)and PO activity were determined quantitatively in juvenile and adult E.carinicauda under different salinity levels.The results showed that E.carinicauda juveniles could survive in a wider range of salinity conditions than adults.For juvenile E.carinicauda,the expression levels of Ec LGBP and Ec Pro PO were upregulated in low salinities and showed no significant difference at 20–40,while PO activities in low salinities were higher compared to those in high salinities.For adult E.carinicauda,the expression profiles of Ec LGBP and Ecpro PO had a different trend of up-regulation in salinity stress treatments and no obvious difference was observed in the gene expression levels and PO activity between 30 and 40.The salinity tolerance range of immunity for juvenile and adult E.carinicauda is 20–40 and 30–40,respectively.

Effects of water stress and NaCl stress on different life cycle stages of the cold desert annual Lachnoloma lehmannii in China

For a plant species to complete its life cycle in arid and saline environments,each stage of the life cycle must be tolerant to the harsh environmental conditions.The aim of the study was to determine the effects of water stress(water potentials of–0.05,–0.16,–0.33,–0.56,–0.85 and–1.21 MPa)and NaCl stress(50,100,200,300,400,500 and 600 mmol/L NaCl)on seed germination percentage,seedling survival and growth,juvenile growth and plant reproduction of Lachnoloma lehmannii Bunge(Brassicaceae),an cold desert annual that grows in the Junggar Basin of Xinjiang,China in 2010.Results indicated that low water stress(–0.05 and–0.16 MPa)had no significant effect on seed germination percentage.With a decrease in water potential,germination percentage decreased,and no seeds germinated at–0.85 and–1.21 MPa water stresses.Germination percentage of seeds was significantly affected by NaCl stress,and higher germination percentages were observed under non-saline than saline conditions.An increase in NaCl concentrations progressively inhibited seed germination percentage,and no seeds germinated at ≥400 mmol/L NaCl concentration.Non-germinated seeds were transferred from both PEG(polyethylene glycol-6000)and NaCl solutions to distilled water for seed germination recovery.The number of surviving seedlings and their heights and root lengths significantly decreased as NaCl stress increased.About 30% of the plants survived and produced fruits/seeds at 200 mmol/L NaCl concentration.Thus,seed germination,seedling establishment and reproductive stage in the life cycle of L.lehmannii are water-and salt-tolerant,with seedlings being the least tolerant.These tolerances help explain why this species can survive and produce seeds in arid and saline habitats.

Generational Mean Analysis of Salt Tolerance during Osmotic Phase in Maize Seedling

This study details the nature and magnitude of the genetic effects associated with various quantitative characters (morphological and hydric relations) measured in maize seedlings during the osmotic phase of saline stress (100 mM NaCl). Three lines with differential behavior in salt stress: SC2 (tolerant), AFE (susceptible) and LP3 (moderately tolerant) were used to obtain contrasting crosses (SC2 × AFE) and (SC2 × LP3). An analysis of six generational means (P1, P2, F1, F2, BC1 and BC2) was applied for each cross. First a scaling test was applied and then a three and six-parameter genetic models were used to estimate various genetic components. In none of the traits studied there was evidence of adequacy to the three parameter model, which indicates important epistatic effects in genetic expression. The dominant genetic effects were greater than the additive ones for all the characters evaluated. LG showed positive and significant differences for [h] in both crosses, indicating the presence of hybrid vigor and its possible use in the improvement. Low value of [d] and high of [h] both significant in SC2 × AFE, indicates existence of genes dispersion between the parental lines. While, for the cross SC2 × LP3, the low and significant value of [d] and not significant value of [h], indicate greater genetic similarity. In the SC2 × LP3 cross, the negative interaction [l] confirms ambidirectional dominance, while for SC2 × LP3 the positive sign indicates directional dominance. The analysis of tolerance to salinity in the osmotic phase showed a complex polygenic inheritance for the traits used, determined by simple and interaction effects of different magnitudes and significance according to the cross considered.

Yield Gap of Stress Tolerant Rice Varieties Binadhan-10 &Binadhan-11 in Some Selected Areas of Bangladesh

Binadhan-10 & Binadhan-11 are climate smart stress tolerant high yielding rice varieties (yield > 4 t⋅ha−1) have saline tolerant EC up to 12 ds/m and submergence tolerant up to 20 - 25 days capacity. The present study was an attempt to analyze the yield gap of stress tolerant varieties Binadhan-10 & Binadhan-11 in some selected areas of Bangladesh. The objectives of the study were: 1) to estimate the yield gap of Binadhan-10 &-11 growers among the study areas;2) to identify the factors affecting the yield of these variety;and 3) to suggest some policy guidelines to minimize the yield gap. The study was conducted in eight Binadhan-10 & Binadhan-11 growing areas in Bangladesh. In this study, four districts namely Satkhira, Khulna, Barishal, and Cox’s Bazar were used for Binadhan-10 and Mymensingh, Jamalpur, Sherpur and Sunamgonj were taken for Binadhan-11. It is based on primary level data from eight sub-districts among the study areas. A total of 240 farmers were randomly selected (30 from each location) to collect the data with a pre-designed questionnaire. Farmer were grouped according to saline affected and not-affected for saline tolerant variety Binadhan-10 and not affected, affected (1 - 10 days) and highly affected (10 - 20 days) for submergence tolerant rice variety Binadhan-11 to identify existing yield gap. Tabular as well as Zandstra method were applied for analysis the data. The study also found factors affecting the gap and some policy guidelines to minimize the gap.

Salt Tolerance of 15 Rice （Oryza sativa L.） Varieties in the Office du Niger Zone of Mali

From 2003 to 2005, in pot and field experiments, rice response to salinity stress of 15 rice varieties was studied at germination and young seedling stages using salt affected soils collected from rice production areas in the Office du Niger zone of Mali. The rice varieties were composed of 10 rice genotypes from the breeding program of Mali and five from West African Rice Development Association （WARDA） program （Saint Louis, Senegal）. Soil samples were collected from the visually affected soils which were characterized by the appearance of white or black efflorescence on the soil surface. In pot experiments, the genotypes were allowed to germinate in both affected soil types （white efflorescence and black efflorescence） and salt effects on plant seedling growth were observed. Results showed that all varieties were significantly sensitive to salinity stress based on germination, young seedling shoot and root dry weights. Among the rice varieties, the most salt tolerant variety was BG90-2 （a high yielding genotype from the Institut d＇Economie Rurale （IER） breeding program） while the most sensitive variety was Telimani （also from the breeding program of IER）. All other varieties were intermediary between these two genotypes. A three year field experiment conducted in a highly affected area near Niono confirmed the results of the pot experiment. The relatively salt tolerant genotypes were found in both Malian （BG90-2, Kogoni91-1, SK51-5-2） and WARDA （Was30-11-1-1-4-6-1B） rice breeding programs.

Possible Involvement of Anti-Oxidant Enzymes in the Cross-Tolerance of the Germination/Growth of Wheat Seeds to Salinity and Heat Stress

The germination/growth of wheat （Triticum aestivum L. cv. Zimai 1） seeds and changes in the activities of superoxide dismutase （SOD）, ascorbate peroxidase （APX）, and catalase （CAT）, as well as in the content of thiobarbituric acid-reactive substances （TBARS）, in response to salt and heat stress, as well as cross-stress, were investigated in the present study. With increasing temperature and decreasing water potential caused by NaCI solution, the germination percentage of seeds and the fresh weight of seedlings decreased markedly, SOD activity increased, activities of APX and CAT decreased distinctly, and the TBARS content increased gradually. Seeds pretreated at 33℃ for different times displayed increased tolerance to subsequent salt stress, enhanced SOD, APX, and CAT activities, and decreased TBARS content. Seeds pretreated at -0.8 MPa NaCI for different times displayed increased tolerance to subsequent heat stress and marked increases in SOD, APX, and CAT activities, which were associated with decreased TBARS content. It is considered that the common component in the cross-tolerance of the germination and growth of wheat seeds to salinity and heat stress is the anti-oxidant enzyme system.

An efficient corrosion inhibitor of cassava starch graft copolymer for aluminum in phosphoric acid

Starch is one of the richest natural polymers with low-cost,non-toxic and biodegradable,but is seldom directly used as corrosion inhibitor due to its poor inhibitive ability and low water solubility.To solve this problem,cassava starch-acryl amide graft copolymer(CS-AAGC)was prepared through grafting acryl amide(AA)with cassava starch(CS),and it was firstly examined as an efficient inhibitor for 1060 aluminum in 1.0 mol·L^(-1)H_(3)PO_(4) media.The adsorption behavior of CS-AAGC and its electrochemical mechanism were investigated by weight loss and electrochemical methods.Additionally,the inhibited aluminum surface was fully characterized by a series of SEM,AFM,contact angle measurements and XPS.Results confirm that CS-AAGC performs better inhibitive ability than CS,AA or CS/AA mixture,and the maximum inhibition efficiency of 1.0 g·L^(-1)CS-AAGC is 90.6%at 20℃.CS-AAGC acts as a mixed-type inhibitor while mainly retards the anodic reaction.EIS has three time constants,and the polarization resistance is significantly increased in the presence of CS-AAGC.The micrograph of inhibited aluminum surface is of hydrophobic nature with low surface roughness and little corrosion degree.

遮荫对盐胁迫下油葵生长和光合生理的影响

盐碱地光伏系统下作物生长受到盐分和遮荫的双重影响,研究双重逆境下作物的生理响应对该系统内作物种植有重要指导意义。本研究以油葵(Helianthus annuus L.)为试验材料,采用盆栽试验,设3个盐分水平(在初始含盐量的基础上外加NaCl含量0 g·kg^(−1)、3 g·kg^(−1)和5 g·kg^(−1))和4个遮荫水平(0%、30%、60%和90%),探究遮荫对盐胁迫下油葵生长、光合特性、叶片解剖结构、生物量积累和分配及籽粒产量等的影响,为盐碱地光伏系统下开展作物种植提供理论依据。结果表明,不同盐分水平下,与不遮荫(遮荫水平0%)处理相比,遮荫会破坏油葵叶片光合反应中心,降低光能转换效率,减小叶片厚度和栅栏组织层,减少光合产物积累,进而抑制茎粗和花盘的生长,影响光合产物分配方向,最终降低籽粒产量;但适度遮荫下油葵会通过增加株高、增大叶面积、提高核酮糖-1,5-二磷酸羧化酶(Rubisco酶)和磷酸烯醇式丙酮酸羧化酶(PEPC酶)活性等方式提高叶片的光捕获能力,促进光合作用进行。不同遮荫水平下,与无盐分处理相比,轻(3 g·kg^(−1)NaCl)、重(5 g·kg^(−1)NaCl)度盐胁迫均会降低油葵的光合效率,抑制株高、茎粗、花盘和叶片的生长,减少光合产物的积累,最终降低籽粒产量,且不同盐胁迫浓度下油葵生长和光合生理特性在不同遮荫水平的变化规律不一致。其中,30%遮荫水平能显著提高轻度盐胁迫下油葵叶片的Rubisco酶和PEPC酶活性,减小叶片厚度,增大栅栏组织层,提高水分利用效率,进而提高油葵光合效率,促进油葵生长。研究表明弱光环境下油葵会通过改变自身形态、光合酶活性、光合产物分配等方式来应对环境胁迫,且遮荫能在一定程度上缓解盐胁迫对油葵造成的负面影响。其中,30%遮荫水平对缓解轻度盐胁迫引起的油葵光合能力降低和生长抑制的效果较好。

大豆混合盐碱胁迫应答基因GmDUF247-1的克隆及功能分析

我国盐碱地分布广、面积大,是重要的后备耕地资源、粮食增产的“潜在粮仓”。挖掘负调控大豆耐混合盐碱性的基因,通过基因敲除创制耐混合盐碱大豆新品种,是合理开发利用盐碱地,提高我国大豆产量的有效途径之一。课题组前期筛选到1个混合盐碱胁迫下调表达的基因Glyma.02g271000(GmDUF247-1)。其编码的GmDUF247-1蛋白包含1个DUF247结构域和1个跨膜结构域,利用烟草叶片瞬时表达发现GmDUF247-1-GFP融合蛋白定位在细胞膜上。荧光定量PCR显示,GmDUF247-1基因在大豆根中表达量最高,在混合盐碱处理下显著下调。为研究GmDUF247-1在大豆混合盐碱胁迫下的功能,利用大豆毛状根系统过表达GmDUF247-1基因,发现混合盐碱胁迫处理后,GmDUF247-1过表达大豆毛状根复合植株叶片萎蔫程度明显高于空载体对照,存活率、根长和株高显著低于对照。对GmDUF247-1基因在大豆自然群体中的单倍型分析发现,其启动子区有8个SNPs和4个InDels,可能导致与逆境应答和生长发育相关的转录因子识别元件序列发生改变;CDS区存在3种单倍型,GmDUF247-1^(H1)基因型受到了明显的人工选择。本研究初步明确了GmDUF247-1基因负调控大豆混合耐盐碱性,为系统研究GmDUF247-1基因功能和育种利用奠定了研究基础。

松嫩平原耐盐碱大豆品种筛选与利用

为了对不同品种大豆资源的耐盐碱性进行挖掘和鉴定,本研究采用盆栽法,以NaCl∶Na_(2)CO_(3)∶NaHCO_(3)∶Na_(2)SO 4摩尔比为1∶1∶9∶9的100 mmol·L^(-1)混合盐碱溶液于3叶1心期对18份不同大豆品种进行胁迫处理,清水处理作为对照,通过相关性分析和主成分分析对参试大豆耐盐碱性进行综合评价。结果表明,盐碱胁迫导致大豆的株高降低、节数减少,有效分枝、单株荚数、粒数和单株粒重变少,无效荚变多,从而影响产量,9个产量相关性状中总共提取了3个主成分,累计贡献率为70.86%,与第1主成分相关的性状为株高、有效荚数、单株粒数和单株粒重;与第2主成分相关的性状为底荚高度和主茎节数;与第3主成分相关的性状为有效分枝、无效荚数和百粒重。18份大豆的耐盐碱性存在不同差异,通过相对盐害率对18份大豆资源进行分类,共得到高耐盐碱材料4份,耐盐碱材料2份,中耐材料9份,敏感材料3份,其中齐农5号耐盐碱性最好,适宜作为优异耐盐碱资源进行利用。

盐碱胁迫下苹果矮化砧木M9-T337对外源柠檬酸(CA)的响应

【目的】探究不同浓度外源柠檬酸(CA)对盐碱胁迫下苹果(砧木)幼苗生理特性的影响。【方法】以1年生苹果砧木M9-T337为试材,采用盆栽试验法,设置清水浇灌(CK1)、盐碱胁迫(CK2)、盐碱胁迫+0.2 mmol·L^(-1)CA(T1)、盐碱胁迫+0.6 mmol·L^(-1)CA(T2)、盐碱胁迫+1.0 mmol·L^(-1)CA(T3)、盐碱胁迫+1.4 mmol·L^(-1)CA(T4)6个处理,测定各处理叶片的光合荧光参数、叶绿素含量、根系形态、相对电导率(REC)、Na^(+)含量、K^(+)含量、抗氧化酶活性和渗透调节物质含量,并结合主成分分析对结果进行综合分析。【结果】喷施不同浓度柠檬酸可有效降低盐碱胁迫下M9-T337叶片电导率(REC)、胞间二氧化碳浓度(C_(i))以及Na^(+)含量的升高幅度,显著降低叶片相对含水量(RWC)、根系活力、根鲜质量比、叶绿素a(Chl a)含量、叶绿素b(Chl b)含量、叶绿素a+b(Chla+b)含量、净光合速率(P_(n))、气孔导度(G_(s))、蒸腾速率(T_(r))、初始荧光(F_(0))、最大荧光(F_(m))、光化学淬灭系数(qP)、非调节性能量耗散Y(NO)、超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性与过氧化物酶(POD)活性的下降幅度,以及显著增加脯氨酸(Pro)含量,并在T3处理下达到峰值;根据主成分得分排名可知,外源CA对M9-T337盐碱胁迫缓解能力由高到低为:CK1>T3>T2>T4>T1>CK2。【结论】1.0 mmol·L^(-1)的外源CA可更好地增强盐碱胁迫下M9-T337的光合能力,提高抗氧化酶活性,增强生物膜的稳定性以及促进Na^(+)外排、K^(+)区隔化和抑制K~+外排,从而起到缓解盐碱胁迫的作用。

盐碱胁迫下燕麦幼苗生长生理差异及耐盐碱阈值

为研究混合盐碱胁迫对燕麦幼苗生长、生理的影响,计算耐盐碱阈值,选用相对盐碱敏感品种‘白燕5号’和相对耐盐碱品种‘坝莜18号’为试验材料,设置不同浓度的盐碱胁迫处理,分析燕麦生长、生理指标的变化。结果表明:(1)不同浓度盐碱胁迫对‘白燕5号’和‘坝莜18号’幼苗的株高、根长和生物量有不同程度的抑制作用,分别在150 mmol/L和200 mmol/L胁迫时差异显著。(2)随着胁迫浓度的升高,‘白燕5号’SPAD值、P_(n)、G_(s)及T_(r)均呈下降趋势,在100 mmol/L胁迫时差异显著;‘坝莜18号’SPAD值、P_(n)、G_(s)、T_(r)则表现出先升后降的趋势,C_(i)呈先降后升的趋势,胁迫达到200 mmol/L时差异显著。(3)‘白燕5号’和‘坝莜18号’脯氨酸(Pro)和丙二醛(MDA)含量随着胁迫浓度的增加均呈上升趋势,过氧化氢酶(CAT)活性则呈相反趋势,超氧化物歧化酶(SOD)、过氧化物酶(POD)活性呈先升后降的趋势,‘白燕5号’和‘坝莜18号’SOD活性分别在150 mmol/L和200 mmol/L胁迫时达到峰值且差异显著。(4)以株高较对照降低50%为标准,得‘白燕5号’和‘坝莜18号’幼苗对盐碱胁迫的耐受阈值分别为163.4 mmol/L和200.0 mmol/L。综上所述,燕麦幼苗混合盐碱耐受阈值的确定,可为盐碱地燕麦栽培与推广应用提供理论依据。

盐碱胁迫对骏枣养分吸收、积累及运转的影响

为揭示基于树体养分吸收、利用与积累特征的骏枣耐盐碱适应性生理机制,通过测定不同浓度盐碱处理下10年生骏枣各器官中N、P、K、Ca、Mg、Fe、Mn、Zn、Cu、Na等矿质元素的含量,分析养分在骏枣不同器官中的吸收、积累与运输分配特征。结果表明:矿质离子在盐碱胁迫下主要集中在主根、多年生枝,有无盐碱胁迫时Na^(+)都主要聚集在主根中,K+浓度在叶片中最高,可以保持较高的K+/Na^(+)。在低浓度盐碱胁迫(60 mmol·L^(-1))下Mg、Ca的运输能力增强;高浓度盐碱胁迫(180 mmol·L^(-1))下须根至叶片的Mg、Ca运输能力分别显著下降44.7%和33.1%,叶片中Ca^(2+)/Na^(+)、Mg^(2+)/Na^(+)值分别显著降低72.8%和71.6%,但仍大于1;其他器官中K+/Na^(+)、Ca^(2+)/Na^(+)、Mg^(2+)/Na^(+)保持稳定且大于1。相较于CK,高浓度盐碱胁迫下当年生枝中的Mn、Fe含量与多年生枝中的Mg含量分别升高了14.01%、11.11%、10.52%,Cu、Zn、Mn、Fe在须根中的含量分别升高了117.53%、25.65%、84.98%、26.19%,主根中N、P、Zn、Mn、Fe、Ca的含量分别下降了23.07%、15.38%、80.48%、49.58%、8.82%、30.44%。结果表明成年骏枣树的盐适应机制主要是通过根对Na^(+)的聚积作用,以及叶对K、Mg和Ca的选择性吸收能力增强来实现的。

耐盐促生菌提高盐胁迫下植物生长的研究进展

土壤盐渍化是全世界面临的环境难题之一,严重影响作物的生长发育。而施用耐盐促生菌能够快速、高效提高植物的生长量,改善盐渍土壤的性质。介绍了耐盐促生菌的种类,从其促生机制、提高植物耐盐机制的角度出发,阐述了盐胁迫下耐盐促生菌在不同植物中的应用。今后还需加强对耐盐促生菌的筛选、载体固定化以及与土著微生物的相互作用机制方面的研究,以期为耐盐促生菌进一步的大规模使用提供参考。