Growth and nitrogen status of cotton(Gossypium hirsutum L.)under salt stress revealed using^(15)N-labeled fertilizer

利用^(15)N同位素揭示了盐胁迫下棉花氮素的吸收与生长状况

Salt stress is a vital factor limiting nitrogen uptake and cotton growth in arid regions.The mechanisms underlying salt stress tolerance in cotton plants under high soil salinity have not been fully elucidated.Therefore,the aim of this study was to examine the proportion and mechanism of cotton nitrogen uptake under salt stress using the^(15)N isotope labeling technique.Cotton plants were grown in four undisturbed saline soils(1,3,6 and 9 dS m^(-1)),and the experiment was designed using the ENVIRO-GRO(E-G)model.The results showed that the dry matter of roots,stems and leaves of the cotton parts in slightly saline soil(C2,3 dS m^(-1))was not significant compared with the non-saline soil(C1,1 dS m^(-1)).The cotton fruit grown in low-salinity soil(C2,3 dS m^(-1))had significantly higher dry matter than that grown in the other treatments,implying that cotton plants grown in 3 dS m^(-1)soil have the best nitrogen uptake and salt tolerance.Cotton plants grown in weakly(C3,6 dS m^(-1))and moderately(C4,9 dS m^(-1))saline soils exhibited premature senescence.The distribution of total nitrogen and nitrate content in cotton was the best explanatory variable of total^(15)N recovery,of which cotton^(15)N recovery was between 26.1%and 47.2%,and soil^(15)N recovery was between 7.7%and 14.9%.Our findings provide guidance for further exploitation and utilization of saline soil resources and sustainable development of the agricultural soil ecosystem in arid regions.

盐胁迫是限制干旱区棉花生长和氮素吸收的重要因素。然而,随着土壤盐渍化威胁的不断加重,针对未扰动下不同盐碱胁迫对棉花养分吸收的影响尚不清楚。本研究利用^(15)N同位素定量识别不同盐胁迫程度下棉花对N的吸收比例与机制,并通过田间试验设计了4种典型盐渍化土壤。结果表明,低盐渍土棉花根、茎和叶的干物质含量与非盐渍土相比不显著。棉花植株生长在中度盐渍化和重度盐渍土中表现出过早衰老。全氮和硝态氮在棉花中的分布是总^(15)N利用率的最佳解释变量,其中棉花^(15)N回收率在26.1%到47.2%之间,土壤^(15)N回收率在7.7%到14.9%之间。这些发现为干旱区盐渍土资源的进一步开发利用和农田生态系统的可持续发展提供了指导。