Osmotic Adjustment and Growth of Salt-stressed Cotton as Improved by a Bioregulator

For examining links between growth of salinity-exposed cotton and corresponding changes in physiological characters, a bioregulator was used as a tool for specific manipulations. Greenhouse-grown cotton ( Gossy-pium birsutum L. cv. Paymaster 145 ) was subjected to NaCl levels up to 14.9 dS m⁻¹. The bioregulator MCBuTTB, a cytokinin analog with known ability in improving growth and yield in several salt-stressed crops, was applied by imbiding seed (0 or 268 ppm) plus one foliar spray in dosages equaling 0, 1, and 3 kg ha⁻¹ at 45 DAP. MCBuTTB improved germination, growth, flowering, and finally boll weight. This result coincided with lower osmotic and higher water potentials in leaves, higher leaf turgidity, and more agilely reacting stomata. Treated plants had higher K and preferably Na concentrations in its leaves but ion accumulation was not a precondition for osmotic adjustments, because in cotton exposed to a manmtol-simulated drought MCBuTTB triggered a similar osmotic adjustment and sustained vigour. Regression analyses indicated that osmotic adjustment alone did not cause the raised leaf turgidity. All characters which contribute to salinity resistance appeared as mutually depending and interacting but they respond to a regulatory agent of cytokinin-like activity.     

棉花渗透调节与蒸腾速率的日变化关系

大田正常供水条件下，随１ｄ内光照和温度增加，棉花叶水势及渗透势下降，最低水势为－１１．４巴，渗透势为－１４．２巴，其膨压值为２．８巴，表现出渗透调节作用。气孔导度在中午一段时间最高，而蒸腾速率最高点在１２∶００时，之后下降，表明水分胁迫下产生渗透调节作用，使叶片保水力增加，蒸腾减弱。Ｋ＋和可溶性糖变化，以渗透势下降最低时积累最多，是棉花干旱时主要的渗透调节物质。     

Effect of Drought and Nitrogen Availability on Osmotic Adjustment of Five Pearl Millet Cultivars in the Vegetative Growth Stage

Growth of pearl millet (Pennisetum glaucum (L.) R. Br.) is affected in areas with limited and erratic rainfall, often combined with nitrogen deficiency. Therefore, effects of severe drought and nitrogen availability on mechanisms of dehydration avoidance were investigated. Five pearl millet genotypes were cultivated in soil differing in nitrogen availability, low (N1), medium (N2) or high (N3) in a climate chamber. Thirty‐five days after sowing, the plants were exposed to drought for 12 days. Drought decreased leaf area and stomatal conductance strongly and caused leaf rolling. In the youngest fully expanded leaves, drought led to an osmotic adjustment from around ?0.5 to ?0.9 MPa, in N1 and N2 substantially achieved by potassium accumulation. Nitrate contributed to the osmotic adjustment in N2 and N3, proline only slightly, increasingly from N1 to N2, whereas the sum of glucose, fructose and sucrose did not play a role. The dehydration independent osmotic force for water uptake (osmotic potential at full turgor) was under drought strongest at N2 and in the landrace Dembi Yellow stronger than in the cultivars Ashana and Ugandi. This contributed to the higher relative water content (RWC) of ‘Dembi Yellow’, whereas due to other factors nitrogen had no effect on the RWC.     

高温胁迫对观赏凤梨叶片抗氧化系统和渗透调节物质积累的影响

采用盆栽试验,研究了40℃高温胁迫处理对观赏凤梨叶片抗氧化系统及渗透调节物质积累的影响。结果表明,与25℃对照相比,高温胁迫8 h内,观赏凤梨叶片超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性显著升高,脯氨酸（Pro）和热激蛋白（HSP）含量显著增加,同时叶片超氧阴离子（O2-?）产生速率、过氧化氢（H2O2）和丙二醛（MDA）含量、电解质外渗率、叶绿素含量与对照相比均无显著变化,植株生长也无明显伤害,表明SOD、POD、CAT活性的提高以及HSP、Pro含量的增加有利于缓解短期高温胁迫对观赏凤梨的氧化伤害。之后随胁迫时间的延长,叶片SOD、POD、CAT活性逐渐下降至对照以下,HSP和Pro含量降低,同时叶片O2-?产生速率加快,H2O2和MDA含量升高,电解质外渗率增加,可溶性蛋白含量降低,游离氨基酸含量增加,叶绿素和类胡萝卜素含量下降,气孔逐渐关闭,观赏凤梨植株幼叶、成熟叶受伤害症状逐渐加重。     

Relationship of Carbon Isotope Discrimination to Water Use Efficiency and Productivity of Barley Under Field and Greenhouse Conditions

This study was conducted to evaluate the application of carbon isotope discrimination (CID) as a selection criterion for improving water use efficiency (WUE) and productivity of barley (Hordeum vulgare L.) under field and drought‐stress conditions in a greenhouse. A total of 54 genotypes were screened for variability in CID under field conditions, while 23 genotypes were evaluated under water‐deficit conditions in the greenhouse. A survey of leaf CID of 54 genotypes at two field locations showed more than 2.14‰ difference between extreme genotypes. Significant (P ≤ 0.05) genotypic variation was found in WUE and CID that had a negative strong correlation. There was a negative correlation between leaf CID and aerial biomass in the greenhouse and among six‐row genotypes in the field. Correlations between leaf CID across field locations and across irrigation regimes in the greenhouse were significant (experiment 1, r = 0.79 and 0.94 for six‐ and two‐row genotypes), suggesting stability of the CID trait across different environments. Overall, these results indicate the potential of leaf CID as a reliable method for selecting for high WUE and productivity in barley breeding programmes in the Canadian prairies. Further work is currently underway to determine heritability/genetics of leaf CID and application of molecular marker‐assisted selection for the traits in barley breeding programmes.     

盐胁迫对冬小麦花后抗氧化酶、渗透调节物质的影响

探究小麦花后遭遇盐胁迫下,小麦抗氧化酶、渗透调节物质的变化。本试验以‘青麦6号’、‘济麦22’为材料,以普通土壤为对照,设置2‰、4‰2个NaCl浓度盐胁迫梯度。利用土壤水分用时域水分测定仪(TDR)严格控制0~40 cm土层灌水量,获取冬小麦花后0、7、14、21、28天的小麦旗叶,测定旗叶中超氧化物酶(SOD)活性、过氧化物酶(POD)活性、可溶性蛋白含量、丙二醛(MDA)含量、可溶性糖含量、游离脯氨酸含量的变化。结果表明,随盐浓度及胁迫时间的增加,叶片SOD活性、POD活性、可溶性蛋白含量不同程度的减小;MDA含量、可溶性糖含量、游离脯氨酸含量不同程度地升高。‘青麦6号’具有较好的抗盐性,游离脯氨酸含量与小麦耐盐性呈正相关关系,SOD、POD、MDA能够作为作物抗逆性的衡量标准。     

土壤干旱对小麦叶片渗透调节和光合作用的影响

本文研究了土壤干旱对小麦叶片渗透调节和光合作用的影响.小麦叶片水势、相对含水量、饱和渗透势、光合速率、蒸腾速率和气孔导度随土壤干旱程度加剧呈现出先缓降后陡降的趋势,其变化的土壤相对含水量阈值相同.小麦旗叶的渗透调节能力约为0.5MPa,不同叶位叶片渗透调节能力不同,其强弱顺序为旗叶>倒二叶>倒三叶.干旱使叶片膨压丧失时的渗透势从正常水分处理的-1.61MPa降到-2.33MPa,弹性模量从5.74MPa增加到6.35MPa.干旱条件下的光合速率、气孔导度、气孔限制值和叶片光合放氧能力都下降,而细胞间隙CO_2含量增加,说明光合速率的降低是非气孔因素即叶肉细胞光合活性限制的结果.     

两种黄瓜砧木（南瓜）幼苗对NaCl胁迫的渗透调节响应

摘要: 以两种黄瓜砧木中国南瓜(Cucurbita moschata)杂交种“360-3×112-2”和黑籽南瓜（C. ficifolia）的幼苗为试材,在营养液培养的条件下进行80mmol?L-1 NaC1胁迫,研究了南瓜幼苗的生长、相对含水量、各器官的渗透势和叶片中渗透调节物质含量的变化。结果表明,NaCl胁迫后,两种南瓜幼苗的生长显著受到抑制,“360-3×112-2”幼苗的耐盐性比黑籽南瓜强,“360-3×112-2”幼苗的相对含水量降低较少,各器官的渗透势降低较多,叶片中渗透调节物质含量增加较多。较高的耐盐性与它具较强的渗透调节能力有关。     

植物渗透调节研究进展及与棉花耐旱遗传改良

渗透调节是植物在干旱胁迫下降低渗透势,抵抗逆境胁迫的一种重要方式,是植物的一种重要抗逆生理机制.渗透调节物质合成相关基因在植物中的超表达可提高植物的耐旱性,在棉花耐旱遗传改良方面有着广阔的应用前景.本文综述了近年来几种主要的有机渗透调节物质的研究进展,及其对棉花耐旱遗传改良的意义.     

野生大麦的抗旱性及其在大麦遗传改良中的应用

干旱是主要的非生物胁迫性灾害,极大地威胁到全球的粮食供应,是影响农业生产的最重要因素之一。因此,培育抗旱性植物是解决干旱危害和粮食危机的根本途径。野生大麦已经适应广泛的干旱环境并具有丰富的遗传多样性,它们的抗旱基因与抗旱相关数量性状位点(QTLs)已经确定,对改良大麦抗旱性有巨大的潜力。综述了野生大麦的抗旱性及其在大麦改良中的应用,并对大麦抗旱育种中存在的问题以及今后发展方向进行了展望。     

Carbohydrate Dynamics in Leaves of Rapeseed (Brassica napus) Under Drought

Until now, the carbohydrate dynamics in leaves of rapeseed under drought have largely been unknown. For this reason, a growth chamber study was conducted to examine whether the accumulation of carbohydrates under drought stress contributes to osmotic adjustment in leaf tissue. Plants of the cultivar Titan were subjected to temporary drought in the vegetative and reproductive stages. A third variant of long‐term drought covered the period from leaf development to flowering. The level of sucrose decreased under moderate water deficit, but accumulated under severe long‐term drought. Concentrations of glucose, fructose and trehalose were significantly enhanced and that of raffinose decreased in all the variants of drought. There was no evidence that any of the carbohydrates analysed in this study or the activities of soluble acid and cell wall invertases contributed to a drought‐induced accumulation of osmolytes. The results of this study indicate that osmotic adjustment in response to drought in leaves of the rapeseed cultivar Titan is only limited. It is virtually impossible that carbohydrates function as osmoprotectants in leaves of this cultivar, rising above that of the frequently detected accumulation of proline in rapeseed under water deficit.     

Growth and Ionic Content of Quinoa Under Saline Irrigation

Drought and salinity are the most important abiotic stresses that affect plant's growth and productivity. The aim of the present work was to evaluate the effect of salt and water deficit on water relations, growth parameters and capacity to accumulate inorganic solutes in quinoa plants. An irrigation experiment was carried out in 2009 and 2010 in the Volturno river plain. Three treatments irrigated with fresh water (Q100, Q50 and Q25) and three irrigated with saline water (Q100S, Q50S and Q25S) were tested. For saline irrigation, water with an electrical conductivity of 22 dS m^?1 was used. Actual evapotranspiration (ET_a), water productivity (WP), biomass allocation, relative growth rate (RGR), net assimilation rate (NAR), specific leaf area, leaf area ratio and ions accumulation of quinoa plants were evaluated. WP and plant growth were not influenced by saline irrigation, as quinoa plants incorporated salt ions in the tissues (stems, roots, leaves) preserving seed quality. Treatment with a reduction in the irrigation water to 25 % of full irrigated treatment (Q25) caused an increase in WP and a reduced dry matter accumulation in the leaves. Quinoa plants (Q25) were initially negatively affected by severe drought with RGR and NAR reduction, and then, they adapted to it. Quinoa could be considered a drought tolerant crop that adapt photosynthetic rate to compensate for a reduced growth.     

Selection of Barley Lines for Drought Tolerance in Low-Rainfall Areas

An experiment was conducted at five locations in Jordan (Khanasri, annual rainfall 150 mm; Ramtha, 225 mm; Muwaqar, 150 mm; Rabba, 350 mm; Ghweer, 250 mm) during the 1996/1997 growing season, to evaluate the yield performance and some agronomic traits of 84 barley breeding lines and three long‐term checks (Zanbaka, Arta and Klaxon) for drought tolerance. An α‐lattice design with two replications and six incomplete blocks for each replication was used. Genotype 6 (WI2291/Tadmor) was found to be superior in grain yield, especially compared to the best check (Arta) at the two wettest locations (Rabba and Ghweer). Genotype 21 (Mo.B1337/WI2291/5/Emir/Sb//CM67/3/F8‐HB‐854‐23/121//148‐221/4/CI 08887/CI05761) out‐yielded the best check (Arta) at the driest location (Khanasri), while genotype 61 (Salmas/Arabia Aswad) produced a higher grain yield than the best check (Zanbaka) at Ramtha. The correlations amongst grain yield, biological yield, straw yield, plant height and harvest index were always significant and positive regardless of the location. The correlations amongst days to heading, days to maturity and grain yield were significant at the two driest locations only. This suggests that different phonologies are required to maximize grain yield in wet and dry environments. Also, the relationship between grain yield and the length of grain‐filling period was positive in the wettest location (Rabba), negative in the driest (Khanasri) and not significant at the two intermediate locations. These results emphasize the importance of selection in the target environment and the need to develop early‐maturing genotypes as a way of withstanding drought and high temperatures during the grain‐filling period. A high and negative correlation coefficient was found between the drought susceptibility index and grain yield at the driest site, whereas at the wettest site the correlation coefficient was lower and in some cases positive, indicating the existence of traits that are desirable under drought and undesirable under favourable conditions.     

垄作栽培对啤酒大麦产量和品质的影响

探讨在等量灌水条件下垄作栽培对啤酒大麦产量和品质的影响。结果表明：（1）垄作栽培生育期长于传统平作栽培,单株穗数低于传统平作栽培,经济系数高于传统平作栽培,株高、穗粒数、产量影响趋势不一致,品种之间存在差异。（2）原麦品质：垄作栽培与传统平作栽培籽粒千粒重之间差异不显著,蛋白质含量之间差异显著,粒筛选率之间差异极显著水平,千粒重、蛋白质含量、筛选率均降低。（3）麦芽品质：垄作栽培麦芽蛋白质含量均较传统平作栽培降低,麦芽细粉浸出物、β-葡聚糖、a-氨基氮、a-淀粉酶、糖化力、可溶性氮之间差异不显著,库值含量之间差异达显著水平,但影响趋势不一致,品种之间存在差异。     

The Effect of Late-terminal Drought Stress on Yield Components of Four Barley Cultivars

Barley (Hordeum vulgare L.) is an important winter cereal crop grown in the semiarid Mediterranean, where late‐terminal drought stress during grain filling has recently become more common. The objectives of this study were to investigate the growth performance and grain yield of four barley cultivars under late‐terminal drought stress under both glasshouse and field conditions. At grain filling, four barley cultivars (Rum, ACSAD176, Athroh and Yarmouk) were exposed to three watering treatments: (1) well‐watered [soil maintained at 75 % field capacity (FC)], (2) mild drought stress at 50 % FC, (3) severe drought stress at 25 % FC in the glasshouse experiment and (1) well‐watered (irrigated once a week), (2) mild drought (irrigated once every 2 weeks), (3) severe drought (non‐irrigated; rainfed) in the field. As drought stress severity increased, gross photosynthetic rate, water potential, plant height, grain filling duration, spike number per plant, grain number per spike, 1000‐grain weight, straw yield, grain yield and harvest index decreased. In the glasshouse experiment, the six‐row barley cultivars (Rum, ACSAD176, and Athroh) had higher grain yield than the two‐row barley cultivar (Yarmouk), but the difference was not significant among the six‐row cultivars under all treatments. In the field experiment, Rum had the highest grain yield among all cultivars under the mild drought stress treatment. The two‐row cultivar (Yarmouk) had the lowest grain yield. In general, the traditional cultivar Rum had either similar or higher grain yield than the other three cultivars under all treatments. However, the yield response to drought differed between the cultivars. Those, Rum and ACSAD176, that were capable of maintaining a higher proportion of their spikes and grains per spike during drought also maintained a higher proportion of their yield compared with those in well‐watered treatment. In conclusion, cultivar differences in grain yield were related to spike number per plant and grain number per spike, but not days to heading or grain filling duration.     

Osmotic potential at full turgor: an easily measurable trait to help breeders select for drought tolerance in wheat

This study investigated the relationship between osmotic potential at full hydration (π₁₀₀) and turgor loss point (Ψ_TLP) in wheat (Triticum aestivum) to determine the potential of using π₁₀₀ to predict Ψ_TLP under well‐watered (WW) and drought (WS) conditions. Two methods for determining π₁₀₀ were tested: pressure–volume (PV) analysis and freezing point osmometry. The study also measured π₁₀₀ in a range of 38 field‐grown wheat cultivars to determine whether there is genetic variation in π₁₀₀ under field conditions. π₁₀₀ correlated with Ψ_TLP using both methods under both water treatments, particularly WS. Genetic variation of π₁₀₀ in the field, under rainfed conditions, was greater than controlled conditions and ranged from ?0.94 to ?1.95 MPa. Overall, the evidence supports development of π₁₀₀ as a novel tool for plant breeders to screen large populations of wheat and identify genotypes with lower Ψ_TLP, an integrative trait that is related to drought tolerance.     

Hybrid performance of sorghum and its relationship to morphological and physiological traits under variable drought stress in Kenya

Sorghum, Sorghum bicolor L. Moench, is grown mostly in semi-arid climates where unpredictable drought stress constitutes a major production constraint. To investigate hybrid performance at different levels of drought stress, 12 single-cross hybrids of grain sorghum and their 24 parent lines were grown in eight site-season combinations in a semi-arid area of Kenya. In addition, a subset of 20 genotypes was evaluated at the seedling stage under polyethylene glycol (PEG)-induced drought stress. Environmental means for grain yield ranged from 47 to 584 g/m²reflecting the following situations: two non-stress, one moderate pre-flowering, four moderate terminal and one extreme drought stress. Mean hybrid superiority over mid-parent values was 54% for grain yield and 35% for above-ground biomass. Across environments, hybrids out-yielded two local varieties by 12%. Differences in yield potential contributed to grain yield differences in all stress environments. Early anthesis was most important for specific adaptation to extreme drought. Field performance was not related to growth reduction and osmotic adjustment under PEG-induced drought stress. In conclusion, exploitation of hybrid vigour could improve the productivity of sorghum in semi-arid areas.     

干旱胁迫下抗旱高产小麦新品系旱丰9703的渗透调节与光合特性

以抗旱性强的小麦旱丰9703与抗旱性弱的山农215953为试材,对扬花期、灌浆期、乳熟期的渗透调节能力、净光合速率和PSⅡ光化学活性等进行了研究.结果表明,长期大田干旱胁迫下,旱丰9703三个生育时期的叶片相对含水量与渗透调节能力均高于山农215953,扬花期的渗透调节能力最强,分别比灌浆期、乳熟期高0.07和0.3MPa;干旱胁     

外源ABA对渗透胁迫下玉米幼苗根系渗透调节的影响

用ABA处理不同抗旱性的两个玉米品种幼苗根系, 测定了根系的水势、渗透势、渗透调节能力及4种渗透调节物质的变化, 结果表明: 渗透胁迫条件下, ABA能提高根系的水势、降低渗透势、增加渗透调节能力, 且对抗旱性强的鲁玉14号的作用大于抗旱性弱的掖单13号. 正常供水条件下, ABA处理对根系水势的提高有一定的作用, 但对渗透势及     

土壤水分胁迫下小麦叶片渗透调节与光合作用

在土壤水分胁迫过程中,抗旱性强的小麦品种昌乐5号、北农2号与抗旱性弱的品种济南13,鲁麦5号相比,渗透调节能力高0.41Mpa~0.604Mpa;相对含水量少降7%~8%;叶片水势少降0.40Mpa~0.41MPa。水分胁迫使叶片光合能力下降,抗早性强的品种与抗早性弱的品种相比,其下降的平均百分数为;光合速率前者比后者少降17%~22%;气孔导度