Effects of concentrations of sodium chloride on photosynthesis, antioxidative enzymes, growth and fiber yield of hybrid ramie

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• 作者：Chengjian Huang ; Gang Wei ; Yucheng Jie ; Longchang Wang ; Hangfei Zhou ; Chunyan Ran ; Zaocun Huang ; Huijuan Jia ; Shakeel Ahmad Anjum
• 关键词：Ramie ; Gas exchange ; Chlorophyll fluorescence ; Pigments ; Antioxidant enzymes ; Yield ; Salinity stress
• 刊名：Plant Physiology and Biochemistry
• 出版年：March, 2014
• 年：2014
• 卷：76
• 期：Complete
• 页码：86-93
• 全文大小：598 K

文摘

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聽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聽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使/Fm使) and quantum yield of PSII (蠁_PSII) while non-photochemical quenching (NPQ) changed conversely. Photochemical quenching (qP) and electron transport rate of PSII (ETR) increased at 2 and 4聽g NaCl/kg then decreased at 6 and 8聽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 (g_s) 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.