Effect of deep placement of calcium cyanamide,coated urea,and urea on soybean (Glycine max (L.) Merr.) seed yield in relation to different inoculation methods

Abstract

The main objective of this study was to increase the productivity of soybean [Glycine max (L.) Merr. cv. Enrei] seed by deep placement of controlled release nitrogen fertilizers and by the application of different methods of inoculation of bradyrhizobia. Ten days old seedlings in an inoculated paper pot (IPP), in a non-inoculated paper pot (NIPP), and those grown in a vermiculite bed without paper pot (DT) were transplanted to an upland field converted from a drained paddy field in Nagaoka. In addition to the basal application of 16 kg N ha^?1 in the surface layer (Control), deep placement of 100 kg N ha^?1 of urea (Urea), 100-day type coated urea (CU-100), and calcium cyanamide (CaCN₂) treatments were applied at the depth of 20 cm. In the IPP method, a significantly higher seed yield was obtained with the deep placement of CaCN₂ and CU-100 compared with the Urea and Control treatments. A similar tendency was observed for the DT and NIPP methods. Among the same N fertilizer treatments, the seed yield for IPP and DT tended to exceed that for NIPP, although the NIPP roots also showed nodulation probably due to infection with indigenous bradyrhizobia. The percentage of nitrogen derived from atmospheric N₂ estimated by the simple relative ureide method was higher in the plants with CU-100 and CaCN₂ compared with those with the Urea and Control treatments at the RI stage, suggesting that the basal deep placement of CaCN₂ or CU-100 for soybean cultivation enabled the supply of N without concomitant depression of N₂ fixation. Thus the deep placement of cheaper CaCN₂ was found to be as effective as that of CU-100 for enhancing the soybean seed yield.     

模拟干旱和盐碱胁迫对碱蓬、盐地碱蓬种子萌发的影响

为研究干旱和盐碱胁迫对碱蓬(Suaeda glauca)、盐地碱蓬(Suaeda salsa)种子萌发的影响,比较碱蓬和盐地碱蓬逆境生理特性的异同,本研究利用PEG6000、NaCl和Na_2CO_3分别模拟干旱、盐和碱胁迫,配制相同渗透势的PEG6000、NaCl、Na_2CO_3处理液,以蒸馏水处理为对照,对碱蓬、盐地碱蓬种子的萌发与胚的生长进行比较研究。结果表明:1)低渗处理(-0.46 MPa)对碱蓬、盐地碱蓬种子的萌发无显著影响;高渗处理(-1.38MPa、-1.84 MPa)抑制碱蓬、盐地碱蓬种子的萌发。2)当溶液渗透势相等时,NaCl处理下碱蓬种子的萌发率显著大于PEG、Na_2CO_3处理;而等渗PEG、NaCl、Na_2CO_3处理对盐地碱蓬种子萌发率的影响无显著差异。3)PEG、NaCl、Na_2CO_3处理组碱蓬、盐地碱蓬种子的最终萌发率与对照无显著差异。4)在幼苗形成阶段,PEG、Na_2CO_3处理对碱蓬、盐地碱蓬胚的抑制作用显著大于等渗NaCl处理。5)碱蓬、盐地碱蓬胚的生长对NaCl、Na_2CO_3胁迫的响应存在差异。-0.92 MPa NaCl处理抑制碱蓬胚的生长,却对盐地碱蓬产生促进作用;-0.46 MPa Na_2CO_3处理对碱蓬胚的抑制作用小于盐地碱蓬。综合分析表明:碱蓬、盐地碱蓬均具有很强的抗盐性。在种子萌发阶段,碱蓬种子的抗旱、抗碱能力低于盐地碱蓬;在幼苗形成阶段,碱蓬胚的抗盐性小于盐地碱蓬,但对轻度碱胁迫的抗性高于盐地碱蓬。     

2-methylisoborneol and geosmin,the main sources of soil odor,inhibit the germination of brassicaceae seeds

The effects of 2-methylisoborneol (MIB) and geosmin, the main sources of soil odor produced by microorganisms, on plant seed germination were examined for 15 kinds of Brassicaceae seeds including radish (Raphanus sativus var. radicula). Authentic MIB or geosmin was used at the concentration of 100 mg L^-1 in the assay, the effects were quantitatively indexed based on four parameters of cumulative seed germination: the final germination percentage, germination onset, weighted mean rate, germination index. MIB and geosmin inhibited germination of all kinds of seeds tested for these parameters. Radish variety “Comet” was the most affected of all of the tested plant seeds. The estimated 50% inhibitory concentration values on germination of “Comet” were 70.5 and 7.5 mg L^-1 for MIB and geosmin, respectively. We also conducted the primary characterization of the inhibition by MIB and geosmin on “Comet” seeds. Our findings were as follows: (1) onset of seed imbibition was not affected; (2) germination of seeds pre-imbibed in the control solution until approx. 2 h before germination onset was inhibited by subsequent MIB or geosmin treatment; (3) growth of seedlings was not significantly affected; (4) the germination was restored by stratification, gibberellin A₃ treatment, or seed coat removal; and (5) light irradiation affected the degree of inhibition. These results suggest that inhibition by MIB and geosmin is restricted to the germination process, at least in the early stage of growth, that they act as growth -regulating substances.     

The natural aging-related biochemical changes in the seeds of two legume varieties stored for 40 years

Abstract

This study was carried out to evaluate the effect of long-term natural aging on germinability and several biochemical characteristics regarding antioxidative response of both dry and germinating two different clover (Trifolium repens and Trifolium pratense) seeds stored for 40 years. The percent germination of the seeds was monitored for 7 days. The activities of catalase, peroxidase, superoxide dismutase, lipid peroxidation, H₂O₂ levels, and phenolic matter content were tested on 0, 1st, 3rd, and 7th days of germination. On the 7th day of germination, the germination ratios of the old T. repens and T. pratense seeds were 32 and 17%, while freshly harvested seeds showed 99 and 96% germination on the 4th day, respectively. The long-term aging caused an important increase in lipid peroxidation levels of the old dry seeds. Total phenolic content was high in the old dry seeds of T. repens compared with those of T. pratense. Remarkably, the long-term aging caused an important decrease in H₂O₂ content and the activities of catalase and peroxidase enzymes, but an increase in activity of superoxide dismutase in both the old dry seeds. The decreases in germinability of the old legume seeds were well correlated with the increasing level of lipid peroxidation and the decreasing activities of peroxidase and catalase. During the germination of the legume seeds, a noticeable increase was determined only in peroxidase activity in two types of the old seeds, while catalase activity decreased. However, the other biochemical parameters studied did not significantly change between the germinating old seeds and their freshly harvested controls.     

Seed priming improves growth of nursery seedlings and yield of transplanted rice

Abstract

An attempt to improve the performance of rice (Oryza sativa L.) nursery seedlings through seed priming and its effect on the yield after transplantation was made in a field trial. Priming tools employed during the investigation include pre-germination, hydropriming for 48 h, osmohardening with KCl and CaCl₂ (ψs-1.25 MPa) for 24 h, vitamin priming with 10 ppm ascorbic acid for 48 h and seed hardening for 24 h. All the priming techniques resulted in improved germination speed and spread, seedling fresh and dry weight, root and shoot length, number of secondary roots, seedling nitrogen, total sugars and α-amylase activity. Osmohardening with CaCl₂ resulted in the best performance as indicated by improved germination speed and spread, seedling vigour and starch metabolism, followed by hardening and osmohardening with KCl. However, improved starch metabolism in coarse rice was observed in osmohardening with KCl. Higher K and Ca contents were observed in seeds osmohardened with KCl and CaCl₂, respectively. Maximum straw and kernel yield and harvest index were recorded from osmohardening with CaCl₂ in fine and osmohardening with KCl in coarse rice. Increased number of secondary roots and α-amylase activity were accompanied with increased seedling nitrogen and reducing sugars, respectively.     

FeSO4引发提高秦艽种子萌发的生理机制

为探讨FeSO4引发提高秦艽种子萌发抗性的生理机制,同时设置水引发处理,以未作任何处理的种子为对照(CK),研究了0.6%FeSO4引发处理24 h对种子膜透性、储藏性物质、能量、激素及抗性相关酶等方面的影响。结果表明:FeSO4引发降低了种子膜透性,提高种子活力,在吸水12 h和24 h时,电导率分别较CK降低了6.61%和11.67%;调动了种子内部储藏物质的代谢,蔗糖含量减少9.57%,可溶性蛋白增加49.63%,饱和脂肪酸中的豆蔻酸和木焦油酸甲酯含量分别增加4.93%和9.03%,不饱和脂肪酸中的山嵛酸、油酸、亚油酸和亚麻酸分别减少6.73%、8.18%、8.40%和6.70%;改变了种子激素平衡,其中脱落酸的含量下降64.78%,赤霉素含量增加近22倍;加速了种子能量代谢, ATP含量增加2.16倍,细胞色素C氧化酶活性增加67.91%。此外,FeSO4引发使线粒体非酶促系统中谷胱甘肽含量和抗坏血酸的含量分别增加74.08%和10.89%,使细胞内酶促系统超氧化物歧化酶、过氧化氢酶和抗坏血酸过氧化物酶活性分别增加285%、179%以及19.6%。因此,FeSO4引发对种子萌发是一个综合过程,一方面可促进种子物质代谢和提高能荷水平,一方面可改善种子内部生理状态和提高胁迫响应能力,从而提高种子活力,促进种子快速和整齐萌发。     

DCPTA对干旱胁迫下玉米种子萌发影响的无损检测

为探究2-(3,4-二氯苯氧基)乙基二乙胺(2-(3,4-dichlorophenoxy) ethyl triethylamine,DCPTA)在干旱胁迫下对玉米种子萌发的影响,使用聚乙二醇(polyethylene glycol-6 000,PEG-6 000)和浓度为0.5、1.0、1.5 mg/L的DCPTA混合溶液对玉米种子进行浸泡处理,采用种子标准发芽试验总结得出不同浓度的DCPTA对玉米种子发芽情况影响的规律,再结合低场核磁共振(low field nuclear magnetic resonance,LF-NMR)及核磁共振成像(magnetic resonance imaging,MRI)技术,通过研究其内部水分变化情况、水分迁移规律及水分分布特征解释造成该结果的原因。试验结果表明:一定浓度的DCPTA可以提高玉米种子萌发过程中的耐旱性能,加快种子内部水分的存储速率,提供种子萌发所需的水分条件,减轻干旱胁迫对玉米种子造成的损害。DCPTA对玉米种子干旱胁迫的缓解效果随着其浓度的升高呈现先上升后下降的趋势,以1.0 mg/L的DCPTA处理效果最显著(P<0.05)...     

Salicylic acid alleviates the toxicity effect of cadmium on germination,seedling growth,and amylase activity of rice

Cadmium (Cd) is a toxic heavy‐metal pollutant in the environment. Salicylic acid (SA) is an essential component of plant resistance to pathogens and also plays an important role in mediating plant responses to some abiotic stresses. In the present investigation, the potential effects of SA in alleviating Cd toxicity during seedling stage of rice were studied. Seeds of rice (Oryza sativa L. cv. Xiushui 11) were sterilized and divided into two groups. Half of the seeds were presoaked in 0.1 mM SA solution for 24 h, then both groups were allowed to germinate under various Cd concentrations for 7 d. Cadmium treatments caused a gradual decrease in vigor index, root length, α‐amylase activity, and the mitotic index of root tips. However, pretreatment with SA partially alleviated the negative effect of Cd on germination parameters and increased enzyme activity and mitotic index. Cadmium uptake by seedlings increased with increasing Cd concentration and followed Michaelis‐Menten kinetics. Salicylic acid pretreatment of seeds influenced the Cd level in the seedlings by decreasing V_max. The results suggest that SA plays a positive role in rice‐seed germination and early seedling growth by protecting it against Cd toxicity.     

盐胁迫下外源钙对高羊茅种子萌发和幼苗离子分布的影响

该文模拟了上海市临港新成陆地盐渍化土壤的盐分特点,并在100 mmol/L NaCl盐胁迫下,以常见牧草和草坪草高羊茅（Festucaarundinacea）为材料,在人工气候室可控制条件下,进行了盐胁迫下种子萌发和幼苗盆栽试验,用不同浓度的CaCl2（5、10、20、40、80 mmol/L）处理,研究高羊茅种子萌发和幼苗生长状况,重点研究了矿质元素Na^＋、K^＋、Ca^2＋和Mg^2＋在植株地上部分和地下部分的分布。研究表明：适当浓度的外源CaCl2浸种处理能缓解高羊茅种子受到的盐胁迫伤害,促使种子提前萌发,20 mmol/L CaCl2浸种处理能显著提高种子萌发率,但高浓度（80 mmol/L）的外源钙处理对高羊茅种子萌发不利;适当浓度的CaCl2处理能促进幼苗地上部分生长,降低高羊茅根冠比、稳定植物细胞膜、维持离子平衡、提高植物耐盐性,但是高浓度（80 mmol/L）CaCl2处理会对植物幼苗生长造成伤害。     

Effect of salicylic acid and salt on wheat seed germination

Abstract

The effects of pretreatment with salicylic acid on wheat seed germination (Triticum aestivum L. cv. Roshan), lipid peroxidation, and superoxide dismutase, catalase, polyphenol oxidase, and peroxidase activity were studied under conditions of salt stress. Seeds treated with different concentrations of salicylic acid were used for measuring germination traits. Salt stress was induced by sodium chloride solution. Seeds were soaked in salicylic acid solution for 24 h, dried with sterile paper, transferred to sterile Petri dishes, and treated with 10 ml NaCl solution at different concentrations. After 1 week, the number of germinated seeds, root length, seedling length, and dry weight were recorded. Antioxidant enzyme activity and lipid peroxidation were also assayed. Salinity decreased seed germination. Thus, a high concentration of NaCl (200 mM) decreased germination by 17.6% compared with control treatment. Salicylic acid significantly increased germination in stressed and control seeds. Salicylic acid increased the level of cell division of seedlings and roots, which increased plant growth. Salt stress significantly increased the activity of the antioxidative enzymes catalase, superoxide dismutase, peroxidase, and polyphenol oxidase in wheat seedlings, and salicylic acid reduced the activity of antioxidant enzymes as stress signal molecules. Our results indicated that scavenging of reactive oxygen species was effective, especially by salicylic acid, and that membrane damage was limited. The aim of the present work was to study the character of changes in enzymatic systems induced by NaCl and salicylic acid in wheat seedlings under conditions of salt stress. In brief, salicylic acid treatment reduced the damaging action of salinity on embryo growth and accelerated a restoration of growth processes; thereupon it may be effective for the improvement of seed germination in arid and semi-arid regions.     

Optimizing seed quality during germplasm regeneration inpearl millet

The effect of water stress during flowering and grain filling on seed longevity was studied in three pearl millet genotypes,ICTP-8202, ICTP-8203 and MBH-110. The seeds were produced by three pollination methods; open pollination, selfing(individual panicles enclosed in paper bags), and cluster bagging (panicles from 3–4 adjacent plants enclosed in a paper bag), stored in air-tight plastic bottles underambient conditions (20–40°C,30–80%RH) and germination was tested at 12-month'sintervals. The seeds lost germination completely after six years ofstorage in all treatments. Analysis of variance of the estimates of potential seed longevity (i.e. the seed lot constantK _i of the seed viabilityequation) showed significant effects of water stress andpollination method (P < 0.01). The interaction between irrigation treatment and method of pollination control was also significant (P < 0.05). Averaged over genotypes and pollination methods,potential longevity was greatest(K _i = 2.8) in theirrigated control, and averaged over genotypes and irrigationtreatments, it was greatest (K _i= 3.1) in seeds produced by open pollination. Theimplications of these results were discussed in relation to germplasmseed production.     

BREAKING SEED DORMANCY IN THE WHITE SAXAUL TREE (HALOXYLON PERSICUM BOISS. ET BUHSE) AMARANTHACEAE

Seed dormancy is an obstacle to revegetation and reclamation efforts, particularly in arid and semiarid environments. Therefore, the objective of this study was to determine the most effective germination pretreatment for Haloxylon persicum, a tall desert shrub or small tree. The experiment employed a completely randomized block design. Dormancy breaking treatments included scarification with 98% sulfuric acid for 10, 20, 30, and 60 minutes; debracting seeds; debracting + piercing seeds; stratification for 1, 2, 3 and 4 weeks; and leaching seeds in flowing water for 1, 2, 3, and 4 days. Results demonstrated that scarification with 98% sulfuric acid for 10 min was the most effective treatment which increased germination from 23.3% (control) to >82.6%.     

Characterization of ammonia oxidizing bacteria associated with weeds in a Japanese paddy field using amoA gene fragments

Abstract

Ammonia oxidizing bacteria (AOB) are important microorganisms in rice paddy field ecosystems because they play a key role in the nitrogen (N) cycle by converting ammonia (NH₃) to nitrite (NO^? ₂). In this study, we investigated AOB associated with three types of weeds in a Japanese paddy field (semi-aquatic Echinochloa oryzicola Vasing, floating Lemna paucicostata Hegelm and submerged Najas graminea Delile) using molecular techniques polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and DNA sequencing targeting ammonia monooxygenase (amoA) gene. This work confirmed that rice paddy weeds harbor AOB and that the community composition is different for each type of weed. However, all AOB sequences associated with the tested weeds were closely related to known species of Nitrosospira-like AOB isolated from soil, suggesting that AOB associated with weeds were not specific to weeds and can also be found in the soil. Nitosomanas-like AOB were not detected on any of the weeds tested. In addition, the most dominant AOB strains present in the tested weeds were closely related to Nitrosospira sp. Ka3 and Nitrosospira sp. CT2F. The phylogenetic tree revealed that most of the AOB detected in the present study belonged to amoA cluster 1.     

Na compound fertilizer stimulates growth and alleviates water deficit in the succulent xerophyte Nitraria tangutorum (Bobr) after breaking seed dormancy

Nitraria tangutorum (Bobr), a typical succulent xerophyte with high level of seed dormancy, is one of the few shrubs found to date that can develop and form fixed dunes in desert regions. Our studies have demonstrated that the strong drought tolerance of the succulent xerophytes was strongly linked to high sodium (Na⁺) accumulation in the photosynthesizing branches (PB) as well as leaves. The study is to explore a method that can rapidly promote the seed germination of N. tangutorum, and then investigate the positive effects of Na compound fertilizer (NaCF) on the growth and drought tolerance of N. tangutorum and ecological environment by short-term pot experiment in a greenhouse and long-term field and pot experiment in a desert environment. The results indicate that the germination rate of seeds obtained a maximum by 69% when seeds were treated with 150 mg L ^?1 gibberellic acid (GA₃) for 48 h followed by soaking in concentrated sulfuric acid (98% H₂SO₄) for 55 min, and then germinated (25/5°C) in darkness for 8 d. After breaking seed dormancy, the NaCF significantly stimulated growth of N. tangutorum and, concomitantly, improved its ability to cope with water deficit (30% of field water capacity) by increasing Na⁺ more than Potassium (K⁺) accumulation for osmotic adjustment in greenhouse and desert conditions. The contribution (take the pot experiment in the desert, for example) of Na⁺ to the osmotic potential (compared with control) varied from 13.9% in plants subjected to diammonium phosphate [(NH₄)₂HPO₄] to, surprisingly, 63.9% in plants grown in the presence of NaCF under water deficit. The distribution characteristics of the total Na⁺ (1620 mg) in the NaCF indicate that 691.2 mg (42.7%) is absorbed by plants, 848.8 mg (52.4%) remained in the pot and 80 mg (4.9%) leached, which accounted for 2.2% of the nursery soil, respectively. The positive effect of NaCF on the drought resistance of N. tangutorum and the ecological environment were also confirmed in the field experiments. These findings suggest that the rapid seed germination technology of N. tangutorum combined with the popularization and application of NaCF can shorten the seed germination period and make the seedling establishment much easier, which may be an effective strategy to restore and reconstruct degraded vegetation in many desert regions.     

Assay system for measurement of denitrification-N loss from ornamental plants potted in peat substrate

An assay system was evaluated for denitrification measurement with potted ornamental plants cultivated in peat substrate (Pelargonium zonale, Euphorbia pulcherrima). Flow-through chambers only enclosing the pot of the plants were considered best for denitrification measurement. Loss of N₂O from the chambers by transport through the plant shoot was negligible with both species. To determine (N₂O + N₂)-N loss, C₂H₂ was applied to inhibit reduction of N₂O. Experiments were conducted with unplanted substrate in closed incubation systems to determine optimum C₂H₂ concentration and pre-treatment duration. Complete inhibition of N₂O reduction in peat substrate was achieved using 1 vol% C₂H₂. However, a concentration of 5 vol% C₂H₂ was chosen for further experiments because C₂H₂ concentrations in flow-through chambers varied. The duration of C₂H₂ pre-treatment (0, 2, 12, 24 h) showed no clear effect on (N₂O + N₂)-N accumulation. However, a pre-treatment duration of 2 h was chosen to guarantee immediate inhibition of N₂O reductase at the start of experiments. Exposure to C₂H₂ gas proved to affect plants of both species. During C₂H₂ exposition in flow-through chambers, the leaves of P. zonale became chlorotic (48 h) and necrotic (72 h). E. pulcherrima showed no chlorosis but did exhibit leaf epinasty (24 h) and wilting (96 h). Transpiration of P. zonale and C availability in the growing medium of both species were not affected by 52 h and 24 h treatments with C₂H₂, respectively. As N emissions usually ended within 38 h of C₂H₂ treatment, it was concluded that side effects of C₂H₂ did not affect denitrification measurements.     

Effect of different foliar zinc application at different growth stages on seed zinc concentration and its impact on seedling vigor in rice

This study evaluated how zinc (Zn) concentration of rice (Oryza sativa L.) seed may be increased and subsequent seedling growth improved by foliar Zn application. Eight foliar Zn treatments of 0.5% zinc sulfate (ZnSO₄?·?7H₂O) were applied to the rice plant at different growth stages. The resulting seeds were germinated to evaluate effects of seed Zn on seedling growth. Foliar Zn increased paddy Zn concentration only when applied after flowering, with larger increases when applications were repeated. The largest increases of up to ten-fold were in the husk, and smaller increases in brown rice Zn. In the first few days of germination, seedlings from seeds with 42 to 67?mg Zn?kg^?1 had longer roots and coleoptiles than those from seeds with 18?mg Zn?kg^?1, but this effect disappeared later. The benefit of high seed Zn in seedling growth is also indicated by a positive correlation between Zn concentration in germinating seeds and the combined roots and shoot dry weight (r?=?0.55, p?相似文献   

Alleviation of ionic and osmotic stress of salinity in seedling emergence of Lolium perenne L. with halopriming treatments growing in an hydroponic system

In this paper, we presented a simple and inexpensive model of hydroponic system in laboratory. The six halopriming treatments were used in research. One-third strength nutrient solutions used in hydroponic systems. The ionic and osmotic stresses were induced by adding sodium chloride (NaCl) or polyethylenglycol-6000 to the nutrient solution. Each treatment was conducted three replications in a completely randomized design. The results showed that haloprimig significantly decreased the management (MGT) of Lolium perenne as compared with control. Haloprimed with NaCl for 72, 48 h and magnesium chloride (MgCl₂) for 24 and 72 h showed significant difference as compared with non-treated seed in same stress level. Indeed, it shows that exposure to sodium chloride and magnesium chloride had a priming effect and seedling emergence was significantly increased in comparison to control. The beneficial effects of NaCl on seed germination is due to the uptake of Na⁺ and Cl^? ions by the seed, thus maintaining a water potential gradient allowing water uptake during seed germination.     

Physiological and Biochemical Responses of Acacia Seyal (Del.) Seedlings under Salt Stress Conditions

In this study, the first experiment analyzed the effects of 0, 85, 171, 256, and 342 mM sodium chloride (NaCl) on the germination of Acacia seyal seeds. In the second in vitro experiment, the effects of inoculation with two rhizobial strains on growth, physiological, and biochemical responses of A. seyal seedlings was evaluated at four levels (0, 85, 171, and 256 mM) of NaCl. Results showed that at 342 mM NaCl, germination rate of A. seyal seeds declined by 56% from the control value, while any germination was recorded for Acacia bivenosa and Acacia sclerosperma seeds at the same salt level. Salt stress gradually decreased the growth, the soluble protein and the leaf-chlorophyll contents of A. seyal seedlings. However, rhizobial inoculation limits these adverse effects of salt on physiological and metabolic processes responses. A. seyal exhibited a moderate halophytic behavior; nodulation was enhanced by moderate salt stress.     

Soil salt and NaCl have different effects on seed germination of the halophyte Suaeda salsa

Seed germination is a key life‐history stage of halophytes. Most studies on seed germination of halophytes have focused on the effects of a single salt, while little information is available on the effects of mixed salt in the natural habitat. Due to the contribution of multiple ions in saline soil, we hypothesized that the effect of mixed salt on seed germination will differ from that of a single salt and the mechanism of how germination is affected will differ as well. The effects of mixed salt and NaCl on germination, water imbibition, and ionic concentrations of seeds of Suaeda salsa (L.) Pall. were compared at various salinity levels. Germination percentage (GP) and rate (GR) decreased with increasing salinity level, regardless of salt type. There was no difference in GP or GR between mixed salt and NaCl when the salinity level was below 20 dS m^?1. Above 20 dS m^?1, GP and GR in NaCl were lower than those in mixed salt. At the same salinity level, Na⁺ concentration in seeds was higher in NaCl than that in mixed salt, but the reverse was true for Ca²⁺ and Mg²⁺ concentrations. Imbibition rate for seeds in NaCl was lower than that in mixed salt at the same salinity level. Addition of Ca²⁺ and Mg²⁺ alleviated the inhibition of NaCl on seed germination. In conclusion, our results suggest that the effects of soil salts and NaCl on seed germination are different, and using NaCl instead of soil salt might not be realistic to show the effect of saline stress on seed germination of halophytes in the natural habitat.     

Germination,growth and starch breakdown in Cl3 Fe pretreated pea and barley seeds

Pea and barley seeds were soaked for 3 hours in Cl₃Fe solutions of 0, 50, 500, 2500 and 5000 ppm of iron. The influence of this pretreatment on germination, seedlings growth and starch breakdown was subsequently determined. These results were related to the capacity of iron accumulation in seeds and it subsequent transport to the seedlings.