Gibberellic acid and kinetin partially reverse the effect of water stress on germination and seedling growth in chickpea

The percent germination and seedling growth of chickpea (Cicer arietinum L. cv. PBG-1) decreased with increasing concentrations of exogenous polyethylene glycol 6000 (PEG). With 15% PEG in the growth medium germination was only 33% while with 10% PEG it was 58% as compared to 93% in control. Addition of gibberellic acid (GA₃) and kinetin to medium containing 10% PEG increased the germination and seedling growth and the effect was maximum with 6 µM GA₃ which was a better inducer of growth and germination under reduced water potential than kinetin. However, indole acetic acid (IAA) inhibited germination and growth of stressed seedlings. The activity of amylase in cotyledons under stress was significantly increased with GA₃ while kinetin and IAA were less effective. Gibberellic acid also enhanced the mobilization of starch from cotyledons of stressed seedlings resulting in low starch levels in cotyledons compared with stressed seedlings.     

Effect of Kinetin on Starch and Sucrose Metabolising Enzymes in Salt Stressed Chickpea Seedlings

Higher amylase activity in cotyledons of kinetin treated salt stressed (75 mM NaCl) chickpea (Cicer arietinum L. cv. PBG-1) seedlings, as compared to salt stressed seedlings was observed during a growth period of 7 d. The activities of acid and alkaline invertases were maximum in shoots and minimum in cotyledons under all conditions. The reduced shoot invertase activities under salt stress were enhanced by kinetin with a simultaneous increase in reducing sugar content. Kinetin increased the activities of sucrose synthase (SS) and sucrose phosphate synthase (SPS) in both the cotyledons and shoots of stressed seedlings. Kinetin appears to increase the turnover of sucrose in the shoots of stressed seedlings.     

Effect of GA3, kinetin and indole acetic acid on carbohydrate metabolism in chickpea seedlings germinating under water stress

Enhanced amylase activity was observed during a 7-day-growth period in the cotyledons of PEG imposed water stressed chickpea seedlings grown in the presence of GA₃ and kinetin, when compared with stressed seedlings. During the first 5 days of seedling growth, the seedlings growing under water deficit conditions as well as those growing in the presence of PGRs had a higher amylase activity in shoots than that of control seedlings. Neither GA₃ nor kinetin increased the amylase activity of roots whereas IAA reduced root amylase activity. Activity of acid and alkaline invertases was maximum in shoots and at a minimum in cotyledons. Compared with alkaline invertase, acid invertase activity was higher in all the tissues. The reduced acid and alkaline invertase activities in shoots of stressed seedlings were enhanced by GA₃ and kinetin. Roots of stressed seedlings had higher alkaline invertase activity and GA₃ and IAA helped in bringing the level near to those in the controls. GA₃ and kinetin increased the sucrose synthase (SS) and sucrose phosphate synthase (SPS) activities in cotyledons of stressed seedlings, whereas they brought the elevated level of SPS of stressed roots to near normal level. The higher level of reducing sugars in the shoots of GA₃ and kinetin treated stressed seedlings could be due to the high acid invertase activity observed in the shoots, and the high level of bound fructose in the cotyledons of stressed seedlings could be due to the high activity of SPS in this tissue.     

Trigonelline in mature seeds and developing seedlings of <Emphasis Type="Italic">Glycine max</Emphasis>

Trigonelline (TRG) is known as a compatible solute in response to stress as well as a cell cycle regulator, and is more concentrated in legumes than other non-legume dicots. Four Glycine max L. genotypes (Essex, ExF 67, Forrest and Stressland) were used to examine TRG concentration in seeds and seedlings exposed to 30 or 100 mM NaCl, and to determine the association of TRG concentrations in seedlings with seedling growth. Seed germination across genotypes was inhibited by elevated salinity (71–91 %) in ExF 67 and Forrest and by accelerated aging (77–92 %) in Forrest. Length of seedlings in most genotypes stressed with NaCl apparently decreased. The TRG content in mature seeds of four genotypes was 44.4–74.6 μg g⁻¹(d.m.). TRG content significantly increased during early young seedling development, but remained or significantly reduced in some genotypes stressed with NaCl.     

Indole acetic acid mimics the effect of salt stress in relation to enzymes of carbohydrate metabolism in chickpea seedlings

The effect of addition of indole acetic acid (3 M) andNaCl (75 mM) on growth and enzymes of carbohydrate metabolism inchickpea seedlings was compared. In comparison with control seedlings, theseedlings growing in the presence of indole acetic acid (IAA) had reducedamylase activity in cotyledons and enhanced sucrose synthase (SS) and sucrosephosphate synthase (SPS) activities in cotyledons and shoots at all days ofseedling growth. Compared with control seedlings, sucrose content was higher incotyledons, shoots and roots and reducing sugar content was lower in shoots ofIAA treated seedlings. A low invertase (acid and alkaline) activity in shoots ofIAA treated seedlings could lead to reduced sink strength and hence decreasedgrowth of seedlings. Effects of NaCl stress on growth and activities of amylase,SS and SPS in cotyledons and invertase, SS and SPS in shoots were similar tothose observed with addition of IAA.     

Alleviation of Seed Dormancy in the Desert ForbZygophyllum simplexL. from Pakistan

Zygophyllum simplexL. is a succulent annual that grows on thecoastal and inland saline flats around Karachi, Pakistan. Theseeds are moderately salt tolerant during germination. GerminationofZygophyllum simplexseeds under various salinity, proline,betaine, GA and kinetin treatments was determined. Proline (0.1and 1 mM) and betaine (0.1 and 1 mM) alleviated the innate dormancyof seeds, and germination reached 60–70% compared to 12%in the control set. At low salinity compatible osmotica alleviatedsome effects of salinity, but at higher NaCl concentrationsboth proline and betaine were ineffective. Gibberellic acid(0.3 and 3 mM) and kinetin (0.05 and 0.5 mM) substantially alleviatedboth innate as well as salinity-induced seed dormancy. At highersalinity (125 mM), low concentrations of kinetin (0.05 mM) andhigh concentrations of GA (3 mM) were more effective. GA completelyalleviated the effect of salinity at all concentrations used. Betaine; desert; dormancy; forb; GA; germination; halophyte; kinetin; proline; seeds; Zygophyllum simplex     

ACC conversion to ethylene by sunflower seeds in relation to maturation,germination and thermodormancy

Conversion of exogenous 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene was studied in sunflower (Helianthus annuus L., cv. Mirasol) seeds in relation to germinability. Ethylene production from ACC decreased during seed maturation, and non-dormant mature seeds were practically unable to synthesize ethylene until germination and growth occurred, indicating that ethylene forming enzyme (EFE) activity developed during tissue imbibition and growth. ACC conversion to ethylene was reduced by the presence of pericarp, and in young seedlings it was less in cotyledons than in growing axes.ACC conversion to ethylene by cotyledons from young seedlings was optimal at c. 30°C, and was strongly inhibited at 45°C. Pretreatment of imbibed seeds at high temperature (45°C) induced a thermodormancy and a progressive decrease in EFE activity.Abscisic acid and methyl-jasmonate, two growth regulators which inhibit seed germination and seedling growth, and cycloheximide were also shown to inhibit ACC conversion to ethylene by cotyledons of 3-day-old seedlings and by inbibed seeds.Abbreviations ABA abscisic acid - ACC 1-aminocyclopropane-1-carboxylic acid - CH cycloheximide - EFE ethylene forming enzyme - IAA indole-3-acetic acid - Me-Ja methyl-jasmonate     

外源水杨酸对盐胁迫下大黄种子萌发及幼苗生长的影响

该研究以掌叶大黄、唐古特大黄和药用大黄种子为材料,采用双层滤纸培养法,设置系列浓度NaCl (0、100、150、200、250 mmol/L) 胁迫试验,以及系列浓度水杨酸(SA)溶液(0、50、100、150、200、250 mg/L)拌种和浸种后盐胁迫实验,测定3种大黄种子萌发及幼苗生长指标,揭示外源水杨酸对盐胁迫下大黄种子萌发及幼苗生长的影响。结果显示：(1)随NaCl浓度增大3种大黄种子的发芽率均呈直线下降趋势,且子叶、胚轴、根和苗等生长均受到强烈抑制。(2)在拌种条件下, 200 mmol/L NaCl胁迫下掌叶大黄苗长在200 mg/L SA处理下受到显著促进; 200 mmol/L NaCl浓度盐胁迫下唐古特大黄种子发芽率在250 mg/L SA处理下受到显著抑制;100 mmol/L NaCl胁迫下药用大黄种子发芽势在200 mg/L SA处理下受到显著抑制,其发芽率在150 mg/L SA处理下得到显著抑制,其苗长在250 mg/L SA处理下受到显著抑制。(3)在浸种条件下, 200 mmol/L NaCl胁迫下掌叶大黄种子发芽率在50 mg/L SA处理下显著提高,其幼苗根长和苗长的生长在250 mg/L SA处理受到显著促进;200 mmol/L NaCl胁迫下唐古特大黄种子的发芽势在200 mg/L SA处理下得到显著促进,其幼苗根和苗的生长在50 mg/L SA处理下得到显著促进;100 mmol/L NaCl 胁迫下药用大黄根和苗的生长在100 mg/L SA处理下均得到显著促进。研究表明,3种大黄种子和幼苗对盐胁迫的响应趋势一致,但对不同浓度SA拌种和浸种的响应有较大差异。     

Promotion by 5-Aminolevulinic Acid of Germination of Pakchoi (Brassica campestris ssp. chinensis var. communis Tsen et Lee) Seeds Under Salt Stress

The seed germination and seedling growth of pakchoi (Brassica campestris ssp. chinensis var.communis Tsen et Lee cv. Hanxiao) were not significantly inhibited until the concentration of NaCl was increased to150 mmol/L. Treatment of pakchoi seeds with exogenous 5-aminolevulinic acid (ALA), at concentrations ranging from 0.01 to 10.00 mg/L, promoted seed germination when seeds were stressed by salinity, whereas levulinic acid (LA), an inhibitor of ALA dehydrase, significantly inhibited seed germination and seedling growth, suggesting that metabolism of ALA into porphyrin compounds was necessary for seed germination and seedling growth. Determination of respiratory rate during seed germination showed that ALA increased seed respiration under both normal conditions and salt stress. Furthermore, salt stress decreased levels of endogenous ALA, as well as heme, in etiolated seedlings. More salt-tolerant cultivars of pakchoi contained higher relative levels of endogenous ALA and heme under conditions of salt stress.These results indicate that salt stress may inhibit the biosynthesis of endogenous ALA and then heme,which is necessary for seed germination, and treatment of seeds with exogenous ALA prior to germination may be associated with the biosynthesis of heme.     

Promotion by 5-Aminolevulinic Acid of Germination of Pakchoi （Brassica campestris ssp. chinensis var. communis Tsen et Lee） Seeds Under Salt Stress

The seed germination and seedling growth of pakchoi （Brassica campestris ssp. chinensis var. communis Tsen et Lee cv. Hanxiao） were not significantly inhibited until the concentration of NaCl was increased to 150 mmol/L. Treatment of pakchoi seeds with exogenous 5-aminolevulinic acid （ALA）, at concentrations ranging from 0.01 to 10.00 mg/L, promoted seed germination when seeds were stressed by salinity, whereas levulinic acid （LA）, an inhibitor of ALA dehydrase, significantly inhibited seed germination and seedling growth, suggesting that metabolism of ALA into porphyrin compounds was necessary for seed germination and seedling growth. Determination of respiratory rate during seed germination showed that ALA increased seed respiration under both normal conditions and salt stress. Furthermore, salt stress decreased levels of endogenous ALA, as well as heme, in etiolated seedlings. More salt-tolerant cultivars of pakchoi contained higher relative levels of endogenous ALA and heme under conditions of salt stress. These results indicate that salt stress may inhibit the biosynthesis of endogenous ALA and then heme, which is necessary for seed germination, and treatment of seeds with exogenous ALA prior to germination may be associated with the biosynthesis of heme.     

Effect of salinity on seed germination,ion content and photosynthesis of cotyledons in halophytes or xerophyte growing in Central Asia

Aims We investigated the impact of salinity on seed germination, chlorophyll content, chloroplast structure and photosynthesis of the green embryos in desiccated seeds of the xerophyte Haloxylon persicum, xero-halophyte Haloxylon ammodendron and euhalophyte Suaeda physophora.Methods Seeds of H. persicum, H. ammodendron and S. physophora were collected from natural environment in Fukang, Xinjiang province. Pretreatment with 700 mM NaCl was carried out to stimulate the natural 'seed priming'; we analyzed the joint effect of salinity and different species on germination physiology and cotyledonal structure and photosynthetic function changes during germination and recovery stage.Important findings We found that seeds did not suffer ion toxicity for the two halophytes H. ammodendron and S. physophora, as evidenced by the high final germination after ungerminated seeds pretreated with 700 mM NaCl were transferred to distilled water, but the final germination of the xerophyte H. persicum was significantly lower than that of control. The Na + concentration in embryos increased under salinity for all species, while K + concentration decreased by salinity only for H. persicum and H. ammodendron, i.e. the concentration of K + in embryos of H. persicum and H. ammodendron decreased by 36% and 46%, respectively. For all species, whether dry intact seeds or cotyledons of dry seeds imbibed in deionized water and NaCl solution, had high chlorophyll content. Treatment with NaCl also caused chloroplast thylakoids to swell and chlorophyll content to decrease in seeds of H. persicum, but no significant change was observed in the more salt-tolerant species S. physophora and H. ammodendron. Fluorescence measurement showed that 700 mM NaCl decreased the Fv/Fm ratio of cotyledons in seeds for all species, especially for H. persicum and H. ammodendron. Photosynthetic oxygen releasing was detected from the seeds that were moistened with distilled water and 700 mM NaCl for 6 or 24 h and from the seeds that were initially moistened with 700 mM NaCl in darkness for 10 days, then transferred to distilled water for another 6 and 24 h. The results indicated that the chlorophyll in cotyledon of desiccated seed had photosynthetic function in early germination stage, even under high-saline condition. In addition, the photosynthesis of chlorophyll in the embryonic cotyledons of desiccated seeds during germination was similar to that in leaves of young seedlings for all species. In conclusion, the chloroplasts of the two halophytes were more salt resistant compared with the xerophyte H. persicum. The photosynthetic function of chlorophyll in cotyledons of mature seeds may be ecologically important for seedling development in early stage for plants growing in extremely saline or arid environments.     

Cowpea ribonuclease: properties and effect of NaCl-salinity on its activation during seed germination and seedling establishment

Pitiúba cowpea [Vigna unguiculata (L.) Walp] seeds were germinated in distilled water (control treatment) or in 100 mM NaCl solution (salt treatment), and RNase was purified from different parts of the seedlings. Seedling growth was reduced by the NaCl treatment. RNase activity was low in cotyledons of quiescent seeds, but the enzyme was activated during germination and seedling establishment. Salinity reduced cotyledon RNase activity, and this effect appeared to be due to a delay in its activation. The RNases from roots, stems, and leaves were immunologically identical to that found in cotyledons. Partially purified RNase fractions from the different parts of the seedling showed some activity with DNA as substrate. However, this DNA hydrolyzing activity was much lower than that of RNA hydrolyzing activity. The DNA hydrolyzing activity was strongly inhibited by Cu²⁺, Hg²⁺, and Zn²⁺ ions, stimulated by MgCl₂, and slowly inhibited by EDTA. This activity from the most purified fraction was inhibited by increasing concentrations of RNA in the reaction medium. It is suggested that the major biological role of this cotyledon RNase would be to hydrolyze seed storage RNA during germination and seedling establishment, and it was discussed that it might have a protective role against abiotic stress during later part of seedling establishment.     

NaCl胁迫下海滨锦葵种子萌发和幼苗生长过程的生理特性变化

以1／4 Hoagland溶液为基础培养液,研究了0．5％、1．0%、1．5％、2．0％和2．5％NaCl处理对海滨锦葵[Kostelezkya rirginica（L．）Presl．]种子萌发和幼苗生长的影响,发现随着培养液中NaCl浓度的增加,海滨锦葵种子萌发率逐渐降低;当NaCl浓度达2．5％时种子不萌发,但NaCl胁迫解除后,种子的萌发率水平与对照相当。幼苗在含0．5％～1．0%NaCl的培养液中生长状况良好,叶绿素含量和根系活力明显增高;但当NaCl浓度达1．5％-2．0％时,叶绿素含量和根系活力逐渐下降;与对照相比,NaCl胁迫下幼苗的MDA水平降低。结果表明,NaCl胁迫对海滨锦葵种子萌发和幼苗牛长有一定的影响,但海滨锦葵可通过种子休眠、增加根系活力、降低体内MDA水平来缓解一定的盐害效应．以适应盐胁迫的生长环境．     

Salt sensitivity of the vegetative and reproductive stages in chickpea (Cicer arietinum L.): Podding is a particularly sensitive stage

Soil salinity is an increasing problem, including in regions of the world where chickpea is cultivated. Salt sensitivity of chickpea was evaluated at both the vegetative and reproductive phase. Root-zone salinity treatments of 0, 20, 40 and 60 mM NaCl in aerated nutrient solution were applied to seedlings or to older plants at the time of flower bud initiation. Even the reputedly tolerant cultivar JG11 was sensitive to salinity. Plants exposed to 60 mM NaCl since seedlings, died by 52 d without producing any pods; at 40 mM NaCl plants died by 75 d with few pods formed; and at 20 mM NaCl plants had 78-82% dry mass of controls, with slightly higher flower numbers but 33% less pods. Shoot Cl exceeded shoot Na by 2-5 times in both the vegetative and reproductive phase, and these ions also entered the flowers. Conversion of flowers into pods was sensitive to NaCl. Pollen from salinized plants was viable, but addition of 40 mM NaCl to an in vitro medium severely reduced pollen germination and tube growth. Plants recovered when NaCl was removed at flower bud initiation, adding new vegetative growth and forming flowers, pods and seeds. Our results demonstrate that chickpea is sensitive to salinity at both the vegetative and reproductive phase, with pod formation being particularly sensitive. Thus, future evaluations of salt tolerance in chickpea need to be conducted at both the vegetative and reproductive stages.     

Vigna Radiata Seed Germination under Salinity

Salinity reduced mung bean (Vigna radiata Wilczek) radicle and root elongation, delayed and inhibited hypocotyl elongation and mobilization of reserves from the cotyledons to the embryo axis. Fresh and dry masses and water content of the embryo axes were reduced. Under salinity, a net leakage of K to the media increased with time and increasing NaCl concentrations. Sugars present in the cotyledons of seeds were of primary importance for growth of the embryo axis upto 18 h after sowing whereas breakdown of starch by amylase contributed later, the contribution being delayed and reduced with increasing NaCl concentration. Even when amylase activity in the cotyledons was progressively reduced with increasing NaCl concentration, the increasing contents of soluble sugars in the cotyledons indicated that sugars were not limiting for mung bean seedling growth under salinity.     

黑果枸杞种子萌发及幼苗生长对盐胁迫的响应

研究不同浓度(0、1、2、3、6、9、14、18g.L-1)的盐溶液(NaCl、MgSO4、盐渍土壤)对河西走廊中部荒漠边缘的黑果枸杞种子吸胀、萌发和幼苗生长的影响,并观察胁迫解除后种子的反应。结果表明:黑果枸杞种子吸胀速率随NaCl、MgSO4和土壤溶液浓度的增大呈先升后降的趋势,吸水速度随胁迫时间的延长而减慢;种子萌发率随3种盐浓度的增大而降低,盐胁迫解除后种子仍具有较高的萌发率;发芽指数、活力指数、根长、下胚轴随3种盐浓度的增大而降低或先升后降,根轴比随盐胁迫的增强先升后降;随3种盐浓度的增大,种苗损害率增大,3种盐的胁迫效应依次NaCl>MgSO4>盐渍土壤溶液。黑果枸杞种子萌发和幼苗生长对NaCl胁迫较为敏感,其耐受的临界阈值是6g.L-1;种子萌发能耐受较高浓度的MgSO4的胁迫,幼苗生长对MgSO4胁迫较敏感,其耐受的临界阈值是9g.L-1;种子萌发和幼苗生长对生境盐渍土壤具有较强的耐受能力和适应性。     

盐胁迫环境下不同抗盐性小麦品种幼苗长势和内源激素的变化

采用两种浓度NaCl溶液,对不同抗盐性小麦品种德抗961(抗盐性强)和泰山9818(抗盐性弱)萌发期幼苗进行胁迫处理,观察其幼苗长势和内源激素含量变化.结果表明,盐胁迫抑制小麦幼苗生长,抗盐性弱的泰山9818受抑制较重.苗、根ABA含量随盐胁迫浓度增加而提高,泰山9818的增幅高于德抗961.苗、根IAA含量随盐胁迫浓度增加而降低,但德抗961的IAA含量高于泰山9818,说明盐胁迫下抗盐性强的品种具有较高IAA合成量.2品种GA3含量变化因盐胁迫浓度而异.在低盐胁迫下抗盐性强的品种苗中GA3含量提高以适应盐胁迫利于苗的生长,在高盐胁迫下2品种GA3含量降低.盐胁迫使苗中ZR含量增加,且德抗961的苗中ZR含量高于泰山9818,而根中ZR含量则前者低,说明盐胁迫下抗盐性强的品种可迅速将根部合成的ZR向苗中转移,促进苗的生长.2品种IAA/ABA、GA3/ABA比值随盐胁迫浓度增加和时间延长而下降,德抗961 IAA/ABA比值大于泰山9818.在盐胁迫下,抗盐性强的品种协调自身激素平衡的能力较强可能是其生长受抑制较小的重要原因.     

盐和重金属复合胁迫对翅碱蓬萌发与生长的影响及调控措施

为探究Zn、Cu与盐复合胁迫对翅碱蓬(Suaeda salsa)萌发生长的影响机理及其调控措施,以翅碱蓬为研究对象,采用水培试验方法,测定Zn、Cu和盐复合胁迫条件下翅碱蓬种子发芽率、萌发速率和幼苗渗透调节物质含量等指标,分析1.5 mg/L吲哚乙酸(IAA)、100 mg/L赤霉素(GA)和0.3%硝酸钾(KNO₃)处理对Zn、Cu与盐复合胁迫条件下翅碱蓬萌发与生长的影响。结果表明：(1) Zn、Cu与高盐复合胁迫极显著降低翅碱蓬种子的发芽率,中高浓度的Zn、Cu与盐复合胁迫极显著降低翅碱蓬种子的萌发速率,Zn、Cu和盐复合胁迫对翅碱蓬种子的萌发生长影响表现为低促高抑效应,影响因子间存在明显的协同效应;(2)Zn、Cu和盐复合胁迫条件下,随着盐浓度的升高,翅碱蓬幼苗体内过氧化氢酶(CAT)、过氧化物酶(POD)和超氧化物歧化酶(SOD)3种抗氧化酶活性呈先升高后降低的变化趋势,Zn、Cu和高盐复合胁迫使翅碱蓬幼苗体内丙二醛(MDA)含量增加近2.5倍;(3)1.5 mg/L IAA溶液浸种12 h可显著提高Zn、Cu与高盐复合胁迫条件下翅碱蓬种子的发芽率和萌发速...     

Sodium chloride effects on lipase activity in germinating rape seeds

Seeds of rape (Brassica napus L.) were germinated at various NaCl concentrations up to 200 mM. Germinating levels, seedling growth, triacylglycerol mobilization and lipase activity were investigated. High salt concentrations resulted in retardation of seed germination. Seedling growth as measured by radicle length was severely reduced by NaCl doses higher than 50 mM. Moreover, the mobilization of storage oil in control rapeseed seedlings, started about 24 h after imbibition. As for germination and growth, elevated salt concentrations are found to delay triacylglycerol degradation. Experiments using triolein as substrate indicated clearly that lipase activity was inhibited by salt treatment.     

Effect of salinity on seed germination and seedling growth of the halophyte Suaeda japonica Makino

Seed germination and seedling growth of the annual halophyte species Suaeda japonica Makino were investigated in response to variable salinity of sediment pore water. The germination percentage of S. japonica’s soft brown seeds, which are dominant among dimorphic seeds, decreased with an increase in salinity, although germination was still observed at 1200‐mM NaCl concentration. The germination percentage and germination speed observed in April were higher than those observed in December when treated with sediment water with 400–1200 mM of NaCl concentrations. These data suggest that S. japonica seedlings could be established on sediments that experience high temperatures. Germination recovery of S. japonica seeds transferred from 600‐mM NaCl containing sediment (seawater equivalent) was lowest among 0–1200‐mM NaCl treatments, implying the low tolerance of seawater conditions of S. japonica seeds. Seeds germinated in 900‐ to 1200‐mM NaCl medium showed poor growth, but survived, in hypersaline conditions, and exhibited improvement in growth upon transfer to lower salinity.