盐胁迫下硝态氮对甘薯生长及渗透调节的影响

Effect of Nitrate on Growth and Osmotic Regulation of Sweet Potato Under Salt Stress

采用水培营养液方法,研究盐(NaCl,1、120 mmol/L)、氮(NO_3^--N,1、10 mmol/L)交互对耐盐型(J23)与盐敏感型(S19)2个品种甘薯生长及渗透调节的影响。结果表明:(1)随盐水平提高,耐盐型和盐敏感型甘薯胞间CO2浓度随之下降,净光合速率也受到抑制;地上部和根系全氮含量和有机氮含量下降,其鲜重及生物量减小;(2)随NO_3^--N浓度增加,同一盐水平下耐盐型及盐敏感型甘薯,其Na+、NO_3^--N和脯氨酸含量显著增加,而K+含量明显降低,其中盐敏感型甘薯(S19)的生理表现更为显著;(3)NO_3^--N和脯氨酸含量增加对Na+吸收有明显抑制作用,从而提高了甘薯的耐盐能力;(4)在盐氮交互作用处理下,与耐盐型甘薯相比,盐敏感型甘薯对外界氮浓度更为敏感。上述结果表明,随硝态氮供应量增加,均能提高2种甘薯抗盐胁迫能力,尤其是对盐敏感型甘薯(S19)抗盐效果更为显著。

A hydroponic cultivation experiment was designed to study the effects of nitrate on the growth and osmotic adjustment in sweet potato under salt stress. Two cultivars, including a salt tolerant genotype J23 and salt sensitive genotype S19, were used. Results showed：（1） With the increase of the salt level, the intercellular CO2 content of both salt tolerant（J23） and salt sensitive（S19） sweet potato decreased, and the photosynthetic rate was also inhibited;（2） The concentration of total nitrogen and organic nitrogen in the roots and shoots decreased, and the fresh weight and biomass of sweet potato both decreased;（3） With the increase of nitrogen, the NO_3^--N and proline concentration in both sweet potato genotypes significantly increased, in which the effect in the salt sensitive sweet potato（ S19） was more significant; meanwhile, the increase of NO_3^--N and proline content had a significant inhibitory effect on Na＋ concentration;（4） The NO_3^--N supply improved the osmotic adjustment of both sweet potatoes, and then the salt tolerance was improved, compared with the salt tolerant（J23） sweet potato, the salt sensitive（S19） sweet potato was more positive to nitrogen nutrition, in which the effect of NO_3^--N supply on the plant growth and development was more significant. So the salt stress was alleviated with the nitrate supply in sweet potato, because NO_3^--N improved the plant osmotic adjustment, and the effect was more significant in the alt sensitive species.