盐胁迫条件下杂交水稻种子发芽特性和幼苗耐盐生理基础

两个杂交稻组合汕优 10号和两优培九种子分别放在 H2 O、5 0 mmol/ L、10 0 mmol/ L和 15 0 mmol/ L的 Na Cl溶液中于 30℃下发芽 ,测定种子发芽性能和淀粉酶活性及幼苗保护酶活性、丙二醛 (MDA)含量和脯氨酸、可溶性糖、果糖和蔗糖等相容性溶质含量。结果表明 ,盐胁迫条件下杂交水稻种子平均发芽时间延长 ,发芽指数降低 ,但发芽势和发芽率变化不明显。盐胁迫后明显降低两优培九种子 α,β-淀粉酶活性 ,而汕优 10号中 ,除在 5 0 mmol/ L Na Cl溶液中 α-淀粉酶活性高于对照 (H2 O)外 ,其余处理均降低了α,β-淀粉酶活性。不同盐胁迫程度下杂交水稻幼苗超氧物歧化酶 (SOD)、过氧化物酶 (POD)和过氧化氢酶 (CAT)活性和丙二醛含量及脯氨酸、可溶性糖、果糖和蔗糖等相容性溶质含量变化有差异 ,但未见规律性趋势。杂交水稻幼苗相对含水量和耐盐比率随着盐胁迫程度加深而明显下降。试验还表明 ,盐胁迫条件下杂交水稻组合汕优 10号种子发芽性能比两优培九好 ,淀粉酶和保护酶活性、相容性溶质含量和相对含水量及耐盐指数和耐盐比率也均高于两优培九 ,说明汕优

Inorganic and Organic Compounds of Freshwater Filamentous Cyanobacteria under Normal and Salt Stress Conditions

The main aim of this work was to investigate the effects of salt stress conditions on the inorganic and organic compounds of extracts from six filamentous cyanobacteria： Arthospira platensis, Oscillatoria sp., Oscillatoria salina, Tolypothrix sp., Oscillatoria sp. SWU （Srinakharinwirot University）121 and Tolypothrix sp. SWU213. All cyanobacteria were cultures in BG （blue-green algae）11 medium： pH 7.5 at 35 ℃ for 30 days of sodium chloride in the culture medium presented 0-1.0 M. The cyanobacteria isolates grew well in BGH medium, nevertheless, growth of the majority of isolates was reduced by about 50% in the same medium containing 0.5 M NaCl. The inorganic compounds such as, Na^＋, K^＋, Ca^2＋, Mg^2＋, NH4^＋ and NO3^- were determined. All ions were reduced when NaCI was increased and Na^＋ showed highest amount in the medium followed with Mg^2＋, NH4^＋, NO3^- and Ca^2＋ in all cyanobaeteria. The organic compounds such as, betaine, proline and total lipid were determined under normal and salt stress conditions. We found that all cyanobacteria increased interesting organic compound under salt stress condition at least two folds to compare with normal condition. This is the first finding indicated that freshwater filamentous cyanobacteria could grow under salt stresses by accumulation of some organic compounds as osmoprotectants such as betaine and amino acids, being the reduction related to the amount of inorganies compounds present in cultures.

Effects of Different NaCl Doses on Morphological and Physiological Parameters in Mentha piperita L.

Salt stress is one of the most serious limiting factors for crop growth and production. This study was carried out to evaluate the effects of salt stress in four Mentha piperita L. varieties, in greenhouse conditions. The seedlings were irrigated with 1/2 Hoagland nutrition solutions. Following 10 d of growth in the pots, the seedlings were subjected to salt stress with different concentrations of NaCl （0, 50 and 100 mM, respectively）. Responses of the mint varieties to salt stress were evaluated using some plant growth and physiological parameters, such as plant height, root length, shoot and root fresh and dry weight, and ion concentrations in leaves, such as Na, K, Ca and Cl. Salt stress caused reduction in physiological parameters. However, this reduction was significant at 100 mM NaCl compared to 50 mM NaCl. These two concentrations of NaCl increased Na and Cl contents in leaves. However, K and Ca contents were decreased with salinity. The results showed that Mentha piperita cv. Sewiss and Granada were found more tolerant to salt stress than cv. Marokko and Citaro.

Influence of Saline Stress on Ionic Balance of Wheat （Triticum Aestivum） and Its Wild Congeners

Purpose of this work was to study changes in the ion balance under salt stress in roots and leaves of seedlings of T. aestivum L. and its wild congeners with different genomic composition. Laboratory assessment of salt tolerance in seedlings was carried out and contents of ions K^＋, Na^＋ and Ca^2＋ in roots and leaves were defined. Considerable change of ionic balance in roots and leaves of studied forms of wheat against salt stress is shown. It is noticed that the parity K^＋/Na^＋ decreases in process of strengthening of salt stress. Authentic negative correlation between a relative gain of a biomass of leaves and roots in the stress conditions and accumulation of ions Na^＋ and between a relative gain of a biomass of leaves in the stress conditions and a parity in them of ions K^＋/Na^＋ is revealed. The research results also show that the stability characteristics of indicators of changes in ionic composition or balance in the leaves of young plants are more informative than in the roots and allow to reveal the form, characterized by relatively high of K^＋/Na^＋ ratio and the relatively low accumulation of Ca2^＋ as the most resistant to salt stress.

Effect of the Chemical Mutagens Sodium Azide on Plant Regeneration of Two Tomato Cultivars under Salinity Stress Condition in vitro

The study was carried out to induce variations and stimulate callus induction, plant regeneration from different explants of two tomato （Lycopersicon esculentum Mill.） cultivars Trescantos and super Regina by using tissue culture technique and Sodium azide as a chemical mutagens at concentrations （0.0, 2.0 and 4.0） mM under salinity stress condition at the levels（3.0, 6.0 and 9.0） dS/m. Different plant growth regulators were tested for their potentials in callus induction. The results revealed that treated seeds with SA （sodium azide） at concentration （2.0） mM increased seed germination percentage, seedling height and root length as compare to control treatment. While （4.0） mM concentration cause a reduction in all parameters mentioned above. Concerning to callus induction both cultivars showed a different response against different tested media with varying concentrations of plant growth regulators and despite their variable response to all tested media a combination of （2.0） mg from Kinetin （KIN） and lndol acetic acid （IAA） was found to be the most effective as compare to other treatments. Moreover, when callus transferred to a stressed media the variation was observed in explants fresh weight, and high reduction with the increment of salt level were recorded. Similarly the regeneration efficiency from stressed callus were observed at the level 3.0 and 6.0 dS/m while 9.0 dS/m the callus failed to regenerate plants for all three explants of both tomato cultivars.