Institute of Ramie, Hunan Agricultural University, Changsha 410128, Hunan Province, PR China; Dazhou Institute of Agricultural Sciences, Dazhou 635000, Sichan Province, PR China.
Dazhou Institute of Agricultural Sciences, Dazhou 635000, Sichan Province, PR China.
Plant Physiol Biochem. 2014 Mar;76:86-93. doi: 10.1016/j.plaphy.2013.12.021. Epub 2014 Jan 13.
Ramie (Boehmeria nivea L.) is one of the oldest and most important fiber crops in China due to the comfortable textile of its fine fiber. Increased ramie fiber demand brings ramie cultivation to salt-affected regions. The aim of this research was to determine morphological, physiological and biochemical responses of ramie by subjecting plants to varying concentrations of NaCl (0, 2, 4, 6 and 8 g NaCl/kg dry soil) at vigorous growth stage for 10 and 20 days. Results indicated that salinity stress substantially inhibited the growth of hybrid ramie plants and led to remarkable decline in fiber yield. However, when grown at 2 g NaCl/kg growth and fiber yield were similar to non-saline control. In addition, chlorophyll fluorescence and gas exchange parameters were correlated with growth and yield response. Salt treatments promoted a subsequent decrease in maximum quantum efficiency of PSII photochemistry (Fv/Fm), quantum efficiency of open PSII reaction centers (Fv'/Fm') and quantum yield of PSII (φPSII) while non-photochemical quenching (NPQ) changed conversely. Photochemical quenching (qP) and electron transport rate of PSII (ETR) increased at 2 and 4 g NaCl/kg then decreased at 6 and 8 g NaCl/kg. Substantial decline in the PSII activity at high salinity was associated with the loss of chlorophyll contents. Moreover, marked decrease in net photosynthetic rate (A), transpiration rate (E), stomatal conductance (gs) was also recorded. Nonetheless, intercellular CO2 (Ci) decreased at low salt stress, subsequently increased at high salt stress while water use efficiency (WUE) and instantaneous water use efficiency (WUEi) altered in opposite direction. Substantial decrease of photosynthesis at high salinity was due to non-stomatal factors. Furthermore, salinity stress led to decrease of proteins and accumulation of proline and malondialdehyde (MDA), as well as enhanced activities of superoxide dismutase (SOD, EC 1.15.1.1) and peroxidase (POD, EC 1.11.1.6), whereas, catalase (CAT, EC 1.11.1.7) enhanced at low salinity, decreased at high salinity. Nonetheless, these changes were closely related with the severity and duration of the salinity stress and their interaction. The results suggested a certain tolerance to salinity stress for hybrid ramie. This meets the essential condition for utilization in salinity-prone environments.
苎麻（Boehmeria nivea L.）是中国最古老、最重要的纤维作物之一，因其细纤维的舒适纺织品而备受青睐。随着对苎麻纤维需求的增加，苎麻种植也扩展到了受盐影响的地区。本研究的目的是通过在旺盛生长阶段将植物暴露于不同浓度的 NaCl（0、2、4、6 和 8 g NaCl/kg 干土）下 10 和 20 天，来确定苎麻的形态、生理和生化反应。结果表明，盐胁迫显著抑制了杂交苎麻植株的生长，导致纤维产量显著下降。然而，当在 2 g NaCl/kg 下生长时，生长和纤维产量与非盐胁迫对照相似。此外，叶绿素荧光和气体交换参数与生长和产量反应相关。盐处理促进了 PSII 光化学最大量子效率（Fv/Fm）、开放 PSII 反应中心量子效率（Fv'/Fm'）和 PSII 量子产量（φPSII）的后续下降，而非光化学猝灭（NPQ）则相反。在 2 和 4 g NaCl/kg 时，光化学猝灭（qP）和 PSII 电子传递速率（ETR）增加，而在 6 和 8 g NaCl/kg 时则减少。高盐条件下 PSII 活性的显著下降与叶绿素含量的丧失有关。此外，净光合速率（A）、蒸腾速率（E）、气孔导度（gs）也显著下降。然而，在低盐胁迫下胞间 CO2（Ci）减少，随后在高盐胁迫下增加，而水分利用效率（WUE）和瞬时水分利用效率（WUEi）则呈相反方向变化。高盐下光合作用的显著下降是由于非气孔因素造成的。此外，盐胁迫导致蛋白质减少，脯氨酸和丙二醛（MDA）积累，以及超氧化物歧化酶（SOD，EC 1.15.1.1）和过氧化物酶（POD，EC 1.11.1.6）活性增强，而 CAT（EC 1.11.1.7）在低盐下增强，在高盐下减弱。然而，这些变化与盐胁迫的严重程度和持续时间及其相互作用密切相关。结果表明，杂交苎麻对盐胁迫具有一定的耐受性。这满足了在盐敏感环境中利用的必要条件。
