Content Of Seedlings Research Articles

Hydroponic experiment for identification of tolerance traits developed by rice Nagina 22 mutants to low-phosphorus in field condition

Development of phosphate (P)-deficiency tolerant rice cultivars is constrained by lack of suitable, reproducible, and consistent seedling stage screening methods in breeding programs. This study reports the screening and characterization of M5 mutants derived from an ethyl methane sulfonate treated population of rice cv. Nagina 22 (N22) in low-P field (soil Olsen P 1.94–2.01 mg kg−1; alkaline Vertisol; pH 7.94) for high yield. The present study showed that seedling growth responses such as increase in root weight, root length, root/shoot weight, and dry weight in P-deficient medium can be taken as indices of low-P tolerance in mature plants in field. Total phosphorus content in seedlings showed an inverse relationship with total phosphorus content and low-P tolerance in mature plants in the field. But, phosphorus content in seeds and acid phosphatase activity in the seedling stage were positively correlated with survival and seed set in low-P field. In low-P field, plant height correlated most with yield per plant, and the number of productive tillers in mature plants was highly correlated with tiller number at vegetative stage. These mutants (NH776, NH710, and NH719) have agronomic importance because of their ability to grow and give higher yield than N22 in P-deficient field.

Fall fertilization enhanced nitrogen storage and translocation in Larix olgensis seedlings

Fall nutrient loading of deciduous forest nursery seedlings is of special interest because of foliage abscission and varied translocation patterns. For non-deciduous seed- lings in the nursery, fall fertilization typically can reverse nutrient dilution and possibly increase nutrient reserves; however, this technique has received little attention with deciduous conifer trees that translocate nutrients before abscising foliage. We evaluated how fall nitrogen (N) fertilization affected N storage and translocation in the deciduous conifer Olga Bay larch (Larix olgensis Henry) seedlings during the hardening period. Seedlings were supplied with 25 mg N seedling -1 for 15 weeks before hardening and fall fertilization treatments began with a three week application period of K 15 NO3 at 0, 5, 10 and 15 mg N seedling -1 . During the hardening period, fall N fertilization had little effect on seedling morphology. The N concentration and content of needles decreased dramati- cally as needles abscised, while that of stems and roots increased. Six weeks after fall N fertilization ceased, all seedlings translocated similar net N from their needles. For the control seedlings, this accounted for 84 % of the N stored in stems and roots. For fall fertilized seedlings, however, the proportion of N stored in stems and roots translocated from needles accounted for only 41-61 % of the total because of absorption of fall fer- tilizer that was translocated directly to stems and roots. Six weeks after fall fertilization, the distribution pattern of N concentration and content in seedlings was found in this order: stems ( fine roots ( coarse roots ( needles. Our results suggest that providing deciduous conifer seedlings N during hardening, in this case Olga Bay larch, is a way to promote nutrient loading during nursery production.

Differences and similarities in the photoregulation of gibberellin metabolism between rice and dicots

In rice seedlings, elongation of leaf sheaths is suppressed by light stimuli. The response is mediated by two classes of photoreceptors, phytochromes and cryptochromes. However, it remains unclear how these photoreceptors interact in the process. Our recent study using phytochrome mutants and novel cryptochrome RNAi lines revealed that cryptochromes and phytochromes function cooperatively, but independently to reduce active GA contents in seedlings in visible light. Blue light captured by cryptochrome 1 (cry1a and cry1b) induces robust expression of GA 2-oxidase genes (OsGA2ox4-7). In parallel, phytochrome B with auxiliary action of phytochrome A mediates repression of GA 20-oxidase genes (OsGA20ox2 and OsGA20ox4). The independent effects cumulatively reduce active GA contents, leading to a suppression of leaf sheath elongation. These regulatory mechanisms are distinct from phytochrome B function in dicots. We discuss reasons why the distinct system appeared in rice, and advantages of the rice system in early photomorphogenesis.

Effects of the inhibitor of the γ-aminobutyrate-transaminase, vinyl-γ-aminobutyrate, on development and nitrogen metabolism in Brassica napus seedlings

γ-aminobutyrate-transaminase (EC 2.6.1.19) catalyzes the first step of the catabolism of γ-aminobutyric acid (GABA), a non-protein amino acid well-known to accumulate in plant in response to environmental stimuli. Recent studies reinforce more and more the role of its metabolism in carbon and/or nitrogen metabolisms and as a signalling molecule in developmental processes. Here we investigated the effects of inhibition of γ-aminobutyrate-transaminase (GABA-T) in seedlings of Brassica napus, using vinyl-GABA (VGB) as a specific inhibitor of GABA-T to prevent enzyme activity. Root growth was reduced by 44% in VGB-treated seedlings but was less inhibited when VGB was associated with exogenous GABA and was not reduced with exogenous GABA alone. Measurements of GABA content in seedlings grown on VGB, GABA or VGB+GABA demonstrated that GABA level in root was not linked with the root length reduction, suggesting that GABA was not the sole component acting in root growth inhibition. Besides, metabolic profiling revealed that in root, VGB-treatment caused a twofold increase in content of almost all amino acids, except for alanine whose content was 19-fold higher than in control. In order to test the involvement of alanine accumulation on growth we studied the effects of exogenous alanine. High alanine content slightly reduced root growth suggesting that VGB-induced alanine accumulation was not responsible for root length reduction. We conclude that root growth inhibition in plants whose GABA catabolism was impaired could result at least partly from the disruption of the primary metabolism as a whole rather than direct effect of GABA on cellular growth process.

Biorepress of fumonisin B1 production and their phytotoxicity on growth and ultrastructures of Maize (Zea mays) Seedlings

The results clearly indicated that the seed germinibility in the presence of FB1 was decreased with increasing their concentration, whereas the germinibility was uncompletely ceased at high concentrations, a slight initial lag in germination observed at lowest concentration 28.57 µg /ml and highest concentration 64.11 µg /ml, respectively compared with the control. At concentration of FB1 (28.57 µg /ml), elongation of the hypocotyls and epicotyls in seedlings slightly inhibited compared with the control. Chlorophyll a and b content of seedlings of Zea mays decreased with increasing concentrations of Fumonisin B1. Chlorophyll a content was 6.23, 3.88 and 3.91 (mg/ g fresh weight) at concentrations 28.57, 40.54 and 64.11 (µg /ml) of Fumonisin B1 compared with the control 8.55 mg/ g fresh weight. The ultrastructural studies indicate that there were dramatic differences between the treated and untreated tissues of Zea mays seedlings with the toxin FB1. The treated cells with FB1 are highly vacuolated compared with the untreated cells. Thin layer of external epidermis was observed in untreated cells while thick layer of external epidermis in treated cells was appeared. Sacchaaromyces cerevisiae reduced FB1 to 40.54 (µg /ml) compared with control 64.11(µg /ml) .On the other hand Trichoderma harizianum was more efficient in FB1 productivity where productivity was reduced to 28.57 (µg /ml) with 44.56 %.

Shared mycorrhizal networks of forest herbs: Does the presence of conspecific and heterospecific adult plants affect seedling growth and nutrient acquisition?

Arbuscular mycorrhizal fungi can colonize the roots of a large number of plant species and individuals, simultaneously creating a network of hyphae connecting the roots of many plants. In this study, I examined the effect of the mycorrhizal network produced by conspecific and heterospecific adult plants on growth and nutrient content of seedlings of Arisaema triphyllum (L.) Schott. and Maianthemum racemosum (L.) Link ssp. racemosum. Seedlings of both plant species were planted so that they could become colonized by the mycorrhizal network or remain uncolonized, and were planted in the presence of a conspecific or heterospecific adult plant. After 2 years of growth, seedlings were harvested and biomass and nutrient content were determined. Biomass of A. triphyllum seedlings was not affected by the identity of the adult plant or colonization by mycorrhizal fungi. Biomass of M. racemosum seedlings was significantly affected by adult plant identity and mycorrhizal colonization. Maianthemum racemosum seedlings grown near a conspecific adult were significantly larger than when grown near a heterospecific adult, and mycorrhizal M. racemosum seedlings grown near a heterospecific adult had significantly less biomass than nonmycorrhizal seedlings. This suggests that the mycorrhizal network of some plants may confer positive or negative effects on mycorrhizal seedlings as compared to nonmycorrhizal seedlings.

Effects of copper on growth, accumulation, antioxidant activity and malondialdehyde content in young seedlings of the mangrove species Kandelia candel (L.)

The effects of different concentrations of copper (Cu) on the growth, Cu accumulation, antioxidant enzyme activity and malondialdehyde (MDA) content of seedlings of the mangrove species Kandelia candel L. were investigated. Seedlings were treated with several concentrations of CuCl2 (0, 1, 5, 10, 20, 30 or 40 mg L−1) for 3 months. The results indicated that a high dose of Cu significantly decreased the growth of K. candel in terms of seedling height, leaf number and total biomass. At the highest Cu concentration (40 mg L−1), there was a 39.53% decrease in final seedling height, a 53.25% decrease in leaf number and a 35.96% decrease in total biomass. Cu ions were accumulated mainly in the roots (96%), and only small amounts were translocated to the hypocotyl, leaves and stem. The MDA content increased with increasing external Cu concentration both in roots and leaves. A significantly higher superoxide dismutase, peroxidase and catalase antioxidative enzyme activity occurred in roots and leaves of plants exposed to 20 mg L−1 CuCl2 compared to other treatments, suggesting that K. candel seedlings can tolerate up to 20 mg L−1 Cu treatment.

The upregulation of thiamine (vitamin B1) biosynthesis in Arabidopsis thaliana seedlings under salt and osmotic stress conditions is mediated by abscisic acid at the early stages of this stress response

BackgroundRecent reports suggest that vitamin B1 (thiamine) participates in the processes underlying plant adaptations to certain types of abiotic and biotic stress, mainly oxidative stress. Most of the genes coding for enzymes involved in thiamine biosynthesis in Arabidopsis thaliana have been identified. In our present study, we examined the expression of thiamine biosynthetic genes, of genes encoding thiamine diphosphate-dependent enzymes and the levels of thiamine compounds during the early (sensing) and late (adaptation) responses of Arabidopsis seedlings to oxidative, salinity and osmotic stress. The possible roles of plant hormones in the regulation of the thiamine contribution to stress responses were also explored.ResultsThe expression of Arabidopsis genes involved in the thiamine diphosphate biosynthesis pathway, including that of THI1, THIC, TH1 and TPK, was analyzed for 48 h in seedlings subjected to NaCl or sorbitol treatment. These genes were found to be predominantly up-regulated in the early phase (2-6 h) of the stress response. The changes in these gene transcript levels were further found to correlate with increases in thiamine and its diphosphate ester content in seedlings, as well as with the enhancement of gene expression for enzymes which require thiamine diphosphate as a cofactor, mainly α-ketoglutarate dehydrogenase, pyruvate dehydrogenase and transketolase. In the case of the phytohormones including the salicylic, jasmonic and abscisic acids which are known to be involved in plant stress responses, only abscisic acid was found to significantly influence the expression of thiamine biosynthetic genes, the thiamine diphosphate levels, as well as the expression of genes coding for main thiamine diphosphate-dependent enzymes. Using Arabidopsis mutant plants defective in abscisic acid production, we demonstrate that this phytohormone is important in the regulation of THI1 and THIC gene expression during salt stress but that the regulatory mechanisms underlying the osmotic stress response are more complex.ConclusionsOn the basis of the obtained results and earlier reported data, a general model is proposed for the involvement of the biosynthesis of thiamine compounds and thiamine diphosphate-dependent enzymes in abiotic stress sensing and adaptation processes in plants. A possible regulatory role of abscisic acid in the stress sensing phase is also suggested by these data.

English

Supply of adequate moisture is one of the most important factors limiting agricultural extension and productivity. Ca2+ and K+ are both essential plant nutrients required in a number of developmental and metabolic processes. Both of these nutrients play an important role in ameliorating drought stress in crop plants. This experiment was designed to study whether exogenous application of Ca2+ and K+ before the drought could enhance the potential of plants to survive under limiting water conditions. Brassica napus L. cv Bulbul-98 seedlings were exposed to drought stress for 10 days after exogenous application of different concentrations of Ca2+, K+ and N through irrigation water. Exogenous Ca2+ and K+ application was associated with increased relative water content, membrane stability and chlorophyll content in seedlings exposed to water deficit. Though the quantity of Pro and activities of APX (EC: 1.11.1.11) and CAT (EC: 1.11.1.6) were increased after K+ application, they were strongly induced in seedlings supplemented with Ca2+ in a dose dependent manner. Increasing quantity of N application, however, had a negative effect on these parameters.   Key words: Drought, Ca2+, K+, AOS enzymes, proline, chlorophyll.

Effects of the season and growth stage on the contents of lipids and photosynthetic pigments in brown alga Undaria pinnatifida

Seasonal changes in the contents of lipids and photosynthetic pigments (PSP) in the brown alga Undaria pinnatifida (Harvey) Suringar (Phaeophyceae, Alariaceae) on different stages of its growth were studied. Lipids of all plant growth group comprised glyceroglycolipids (GL), phospholipids, and neutral lipids (NL). The ratio between these lipid groups and the content of particular lipids depended on the season and algal growth stage: NL predominated in seedlings; juvenile algae comprised approximately similar amounts of NL and GL; and in adult algae, GL predominated. In winter and spring, algal tissues contained relatively more free sterols than in summer. Total lipid content in seedlings and juvenile algae was higher then in adult plants. Lipid fatty acid (FA) composition was similar on all growth stages, but the content of major components differed; this is mainly related to 18:4 n-3, 20:4 n-6, and 20:5 n-3 acids. The predominant FAs in seedling lipids were saturated FAs, whereas in the lipids of juvenile and adult algae, polyunsaturated FAs predominated.

Cannabinoid patterns in seedlings of Cannabis sativa L. and their use in the determination of chemical race.

We have examined the cannabinoid contents of seedlings from twelve strains of Cannabis of known chemical race. Fourteen days after emergence of the shoot those of the tetrahydrocannabinol (THC) type could be distinguished from those of the cannabidiol (CBD) type. The true leaves of the THC type contained a relatively high content of THC and also contained cannabichromene (CBC), sometimes as the major cannabinoid, whereas the CBD type had much lower amounts of THC and no CBC; CBD being the major component. A strain from China corresponded to the THC type but showed some unusual features. Seeds purchased at seven outlets in Britain were also examined. Only two batches germinated by these proved to be of a THC type and resembled the Chinese strain.

Effects of soil water and nitrogen supply on the photosynthetic characteristics of <I>Jatropha curcas</I> seedlings

Aims Jatropha curcas is a drought-resistant perennial that can be used for bio-energy to replace petro-diesel. However, J. curcas is still a wild plant and basic agronomical properties are not thoroughly understood. When it is grown in commercial plantations with regular irrigation, we do not know how J. curcas will respond to changes in the environment. Our objective was to evaluate the effects of different soil water and nitrogen supplies on the photosynthesis characteristics of J. curcas seedlings. Methods We exposed seedlings of J. curcas to three watering regimes (80%, 50% and 30% of field water holding capacity (FC)) and two nitrogen (N) regimes (with or without N-fertilization) and determined how N-fertilization affects the photosynthetic light and CO2 response curve, maximal quantum yield of PSII, and N and pigments contents under different soil water conditions. Important findings With N-fertilization, we detected significant increases in apparent quantum yield (AQY), light compensation point (LCP), maximum net photosynthetic rate (Pmax), carboxylation efficiency (CE), photorespiration rate (Rp), dark respiration rate (Rd) and nitrogen content with the increase of soil water content. Highest values of photosynthesis parameters occurred with 80% FC with N-fertilization. Without N-fertilization, all photosynthesis parameters had the opposite trends with the increase of soil water content. Furthermore, with 30% FC the nitrogen content of seedlings with N-fertilization was significantly higher than without N-fertilization. AQY, PSII maximum photochemical efficiency (Fv/Fm) and chlorophyll and carotenoids contents was nearly the same with and without N-fertilization, but other parameters were significantly lower without N-fertilization. Thus, under N-poor soil condition J. curcas grew better under the relatively low soil water conditions and photosynthesis of J. curcas was impacted by high soil water content. While with N-fertilization, J. curcas performed better under high soil water content.

Comparative study of wild and transformed salt tolerant bacterial strains on Triticum aestivum growth under salt stress

Eleven salt tolerant bacteria isolated from different sources (soil, plants) and their transformed strains were used to study their influence on Triticum aestivum var. Inqlab-91 growth under salt (100 mM NaCl) stress. Salt stress caused reduction in germination (19.4%), seedling growth (46%) and fresh weight (39%) in non-inoculated plants. In general, both wild and transformed strains stimulated germination, seedling growth and fresh weight in salt free and salt stressed conditions. At 100 mM NaCl, Staphylococcus xylosus ST-1 caused 25% increments in seedling length over respective control. Soluble protein content significantly enhanced (49%) under salt stress as compared to salt free control. At 100 mM NaCl parental strain PT-5 resulted about 32% enhancement in protein content over respective control treatment. Salt stress induced the promotion of auxin content in seedlings. Overall, Bacillus subtilis HAa2 and transformed E. coli -SP-7-T, caused 33% and 30% increases in auxin content, respectively, were recorded under salt stress in comparison to control.

Effects of potassium and humic acid on emergence, growth and nutrient contents of okra (Abelmoschus esculentus L.) seedling under saline soil conditions.

The effects of potassium and humic acid (HA) on emergence, growth and nutrient contents of okra (Abelmoschus esculentus L cv. Sultani) seedlings in saline soil conditions were evaluated. Different levels of humic acid (0, 500, 1000 and 1500 mg kg-1) and potassium (0, 75, 150 and 300 mg kg-1) were applied on growing media treated with 50 mg NaCl kg-1 before seed sowing. The experiment was designed as randomized completely factorial block and each parcel had ten pots without drainage. Two okra seeds were sown in each pot having 300 cc volumes of growth media. The seedlings were thinned to one after emergence. The seedlings were irrigated with distilled water. Seed emergence, root and shoot size, leaf number, shoot and root dry weights of the plant seedlings were determined. Macro and micro nutrient (N, P, K, Ca, Mg, S, Cu, Fe, Mn and Zn) contents of seedlings were also determined. All data were subjected to a one-way analysis of variance and separated by Duncan’s multiple range test which was performed using the Costat statistical software. There were statistical differences in terms of effects of potassium and HA on the okra seedling performances. The effects of K, Ca, Na, Cu, Fe, Mn, Zn and HA applications on plant mineral (N, P, K, Ca, Cu, Fe, and Mn) contents were significant at p < 0.005. Key words: Okra (Abelmoschus esculentus L.), potassium, humic acid, nutrient content, seedling growth.

Effect of enhanced UV-B radiation and inoculated blast isolate (&lt;I&gt;Magnaporthe grisea&lt;/I&gt;) on phenylalanine ammonial-yase activity and flavonoid content in seedlings of two rice cultivars

本文通过盆栽试验研究增强UV-B辐射和稻瘟病菌联合作用对水稻幼苗叶片苯丙氨酸解氨酶活性(PAL)和类黄酮含量的影响。试验采用3个UV-B辐射强度(2.5 kJ·m^-2、5.0 kJ·m^-2和7.5 kJ·m^-2)、2个稻瘟病菌生理小种(Y98-16T和Y99-63C)对水稻(品种为“黄壳糯”和“合系41”)幼苗叶片进行处理, 测定水稻幼苗苯丙氨酸解氨酶活性和类黄酮含量的变化。结果表明: “黄壳糯”幼苗叶片苯丙氨酸解氨酶活性和类黄酮含量在2.5 kJ·m^-2和5.0 kJ·m^-2 UV-B辐射条件下显著增加, 而在7.5 kJ·m^-2 UV-B辐射条件下显著降低; 2.5~7.5 kJ·m^-2 UV-B辐射导致“合系41”的类黄酮含量显著增加, 5.0 kJ·m^-2 UV-B辐射导致“合系41”的苯丙氨酸解氨酶活性显著增加, 其他UV-B辐射条件下“合系41”的苯丙氨酸解氨酶活性增加不显著。接种稻瘟病菌Y98-16T导致“合系41”的苯丙氨酸解氨酶活性和类黄酮含量显著增加, “黄壳糯”的苯丙氨酸解氨酶活性降低, 类黄酮含量增加; 而接种稻瘟病菌Y99-63C显著降低了“黄壳糯”和“合系41”的苯丙氨酸解氨酶活性和类黄酮含量。UV-B辐射和稻瘟病菌联合作用导致“黄壳糯”苯丙氨酸解氨酶活性和类黄酮含量总体表现出降低的趋势, 而“合系41” 苯丙氨酸解氨酶活性和类黄酮含量一定程度上具有稳定或上升的趋势。总的来讲, UV-B辐射和稻瘟病菌联合作用导致“黄壳糯”敏感性增加, 而“合系41”抗性增强。

산성처리가 애기장대의 엽록소, 카로티노이드, 안토시아닌 등의 색소 함량에 미치는 영향

Arabidopsis seedlings subjected to low pH stress in the range of pH 5.6-4.0 did not show significant retardations in root and shoot growths. Treatment of pH 3.5-2.5 resulted in significant reductions in root and shoot length, especially in roots. Chlorophyll contents in seedlings increased during acid treatment of pH 5.6-4.0, but decreased by stronger acid treatment of pH 4.0 and lower pHs. Total carotenoid contents showed similar trend to chlorophyll contents by increasing during pH 5.6-3.5 treatments and decreasing by pH 3.0-2.5. Anthocyanin contents increased under acid stress of pH 5.6-3.0 and showed great reduction at pH 2.5. The ratios of carotenoids/chlorophylls and anthocyanins/chlorophylls increased by acid stress treatments. That indicates plants try to adjust physiologically to acid stress and protect chlorophylls by increasing carotenoid and anthocyanin contents. However, different responses of chlorophylls and anthocyanins to acid stress indicate both pigments play different roles in protecting plant from acid stress.

Effect of weak constant magnetic field on the composition and content of lipids in radish seedlings at various temperatures

We studied the effects of weak permanent homogenous hirizontal magnetic field (PMF) (400 A/m) on the composition and content of lipids and composition of their fatty acids (FAs) in radish (Raphanus sativus L. var. radicula D.C., cv. Rosovo-krashyi s belym konchikom) seedlings at temperatures of 20 and 10°C. We compared lipid composition and content in seedlings at the phase of developed cotyledons (20°C, 5-day-old, and 10°C, 8-day-old seedlings) under low light and in darkness with the lipid composition and content in dry seeds. The seedlings grown in geomagnetic field (GMF) served as a control. In dry seeds, about 99% of total lipids comprised neutral lipids (NL) and only 1% were polar lipids (PL). Triacylglycerols predominated among NL comprising 93% of total seed lipids. During seed germination, NLs were consumed and PL were produced: the amount of glycolipids increased in control by 3.5-5 times and the amount of phospholipis, by 1.5-2 times.In the light at 20°C, PMF suppressed the formation of PL (by 18%), whereas in darkness, it stimulated it approximately by 80% as compared with control. In the light at 10°C, PMF slightly stimulated PL formation; in darkness, it did not almost affect their synthesis. In all treatments, PMF increased the ratio of phospholipids to sterols by 30-100%. Among FA, PMF exerted the strongest effect on the content of erucic acid: it increased in the light and in darkness at 20°C approximately by 25% and decreased at 10°C in the light by 13%. PMF behaved as a correction factor affecting lipid metabolism on the background of light and temperature action.

Comparative study of wild and transformed salt tolerant bacterial strains on Triticum aestivum growth under salt stress

Eleven salt tolerant bacteria isolated from different sources (soil, plants) and their transformed strains were used to study their influence on Triticum aestivum var. Inqlab-91 growth under salt (100 mM NaCl) stress. Salt stress caused reduction in germination (19.4%), seedling growth (46%) and fresh weight (39%) in non-inoculated plants. In general, both wild and transformed strains stimulated germination, seedling growth and fresh weight in salt free and salt stressed conditions. At 100 mM NaCl, Staphylococcus xylosus ST-1 caused 25% increments in seedling length over respective control. Soluble protein content significantly enhanced (49%) under salt stress as compared to salt free control. At 100 mM NaCl parental strain PT-5 resulted about 32% enhancement in protein content over respective control treatment. Salt stress induced the promotion of auxin content in seedlings. Overall, Bacillus subtilis HAa2 and transformed E. coli -SP-7-T, caused 33% and 30% increases in auxin content, respectively, were recorded under salt stress in comparison to control.

Salt stress effects on growth, pigments, proteins and lipid peroxidation in Salicornia persica and S. europaea

The effects of NaCl stress on growth, water status, contents of protein, proline, malondialdehyde (MDA), various sugars and photosynthetic pigments were investigated in seedlings of Salicornia persica and S. europaea grown in vitro. Seeds were germinated under NaCl (0, 100, 200, 300, 400, 500 and 600 mM) on Murashige and Skoog medium for 45 d. The shoot growth of both species increased under low NaCl concentration (100 mM) and then decreased with increasing NaCl concentrations. In contrast to S. persica, root length in S. europaea reduced steadily with an increase in salinity. Proline content in S. persica was higher than in S. europaea at most NaCl concentrations. Proline, reducing saccharide, oligosaccharide and soluble saccharide contents increased under salinity in both species. In contrast, contents of proteins and polysaccharides reduced in both species under salt stress. MDA content remained close to control at moderate NaCl concentrations (100 and 200 mM) and increased at higher salinities. MDA content in S. europaea was significantly higher than S. persica at higher salinities. Salt treatments decreased K+ and P contents in seedlings of both species. Significant reduction in contents of chlorophylls and carotenoids due to NaCl stress was also observed in seedlings of both species. Some differences appeared between S. persica and S. europaea concerning proteins profile. On the basis of the data obtained, S. persica is more salt-tolerant than S. europaea.

Effects of Cadmium Stress on Seed Germination, Seedling Growth and Seed Amylase Activities in Rice ( Oryza sativa)

Two rice varieties, Xiushui 110 with high cadmium (Cd) tolerance and Xiushui 11 with low Cd tolerance were used to study the effects of Cd stress on seed germination, seedling growth and amylase activities. The low cadmium concentration had little effect on seed germination rate. However, cadmium stress could significantly inhibit plumule and radicle growth, especially for radicle growth. Germination index, vigour index, radicle length and amylase activities of Xiushui 11 decreased more significantly with the increasing cadmium level compared with Xiushui 110. The cadmium content in seedlings of Xiushui 11 was higher than that in Xiushui 110 when the cadmium concentration exceeded 5 μmol/L, which caused lower mitotic index in root tips and amylase activities, and more serious cadmium toxicity in Xiushui 11.