NaCl和Na2CO3胁迫对栓皮栎种子萌发及幼苗生长的影响

为了阐明栓皮栎种子萌发期对盐碱胁迫的耐受性,研究了不同浓度(0、50、100、200和400 mmol/L)NaCl和Na2CO3胁迫对其种子萌发、生长、保护酶活性和有机渗透调节物质等的影响,结果表明:(1)盐碱胁迫对栓皮栎种子的萌发率和发芽指数均没有显著影响;随着Na+浓度的升高,NaCl和Na2CO3处理下的胚根长度、胚根生长速率、胚根鲜重均受到抑制,呈现下降趋势;活力指数和耐盐指数在NaCl胁迫下表现为较低浓度(50 mmol/L)促进,较高浓度(100,200,400 mmol/L)抑制,而在Na2CO3处理下则不断下降;相对盐害率在两种处理下均表现波动趋势。(2)通过建立活力指数、胚根长度等与Na+浓度的回归方程,发现在NaCl胁迫下栓皮栎种子活力指数、胚根鲜重、胚根长度和胚根生长速率的临界值分别为300.0、300.0、333.6、369.6 mmol/L。(3)在NaCl和Na2CO3胁迫下,随Na+浓度的增加,丙二醛含量增幅显著;NaCl处理下的SOD(superoxide dismutase)活性呈现先升高后降低的趋势,而Na2CO3处理下则均低于对照;POD(peroxidase)活性变化不显著;CAT(catalase)活性均表现为先降低后升高;脯氨酸、可溶性蛋白和可溶性糖含量均随着Na+浓度的升高而呈现不同程度上升趋势。(4)等Na+浓度时,NaCl处理下的各项生长指标均高于Na2CO3处理,丙二醛、保护酶活性及渗透调节物质含量均低于Na2CO3处理,说明Na2CO3对栓皮栎种子的影响比NaCl更为显著。

Effects of NaCl and Na2CO3 stresses on seed germination and seedling growth of Quercus variabilis

Choosing fresh cork oak seeds and using Petri dish and filter paper germination method, the NaCl and Na₂CO₃ resistant potential of Quercus variabilis seeds with five different NaCl and Na₂CO₃ concentrations (0, 50, 100, 200 and 400 mmol/L) were examined.During the experimental process, the seed germination, radicle growth, three protective enzyme (SOD, POD, CAT) activities and the organic osmoregulation substances (proline, soluble protein and soluble sugar) were all measured, and the correlation between the seed germination, radicle growth rate under NaCl and Na₂CO₃ stress were analysed.The results showed that: (1) NaCl and Na₂CO₃ stress had no significant impact to seed germination rate and germination index, even under high Na⁺ concentration (200 mmol/L) stress, seed germination rate was still higher than contrast.With the addition of Na⁺ concentration, radicle length, radicle growth rate and fresh weight of radicle under two kinds of stresses presented the downward trend.The vigor index and salt tolerance index under NaCl stress increased at the lower concentrations (50 mmol/L) and then decreased at the higher concentrations (100, 200 and 400 mmol/L), but they both declined under Na₂CO₃ treatment.Relative salt-harmed rate waved under two stresses, they were lower than the contrast under 50 and 200 mmol/L Na⁺ concentration, but were higher under 100 and 400 mmol/L Na⁺ concentration.(2) The regression equation between vigor index, radicle growth rate and different concentrations of NaCl and Na₂CO₃ stress were found, and they showed that the critical value of the vigor index, fresh weight of radicle, radicle length and radicle growth rate under NaCl stress, were 300.0, 300.0, 333.6 and 369.6 mmol/L respectively, they were 69.0, 67.2, 182.0, 187.5 mmol/L respectively under Na₂CO₃ stress.(3) Under two kinds of stresses, with the increase of Na⁺ concentration, MDA (malondialdehyde) content increased significantly; SOD (superoxide dismutase) activity decreased after increasing under NaCl treatment, but they were all lower than the contrast under Na₂CO₃ treatment; POD (peroxidase) activity had no significant change, CAT (catalase) activity was down and then rose.Proline, soluble protein and soluble sugar contents were increased in varying degrees with the addition of Na⁺ concentration, they were to the maximum under the largest concentration of NaCl treatment, and they were all higher than the contrast under Na₂CO₃ treatment (4) Under the same Na⁺ concentration stress, the growth indicators such as seed germination rate, germination index, radicle length, radicle growth rate and fresh weight of radicle under NaCl treatment were all higher than that of Na₂CO₃ treatment, malondialdehyde, protective enzymes (SOD, POD, CAT) activities and osmotic adjustment substances (proline, soluble protein and soluble sugar) contents were all lower than that of Na₂CO₃ treatment, which showed the effects of Na₂CO₃ stress on seeds were more significant than that of NaCl stress.Thus it can be seen that cork oak seeds increased protective enzymes activities and contents of osmotic regulation substances in vivo to adapt to the salt-alkali stress, making the inhibition degree of germination and growth to the minimum.