Zheng Cong Cong, Wang Yong Jing, Sun Hao, Wang Xin Yu, Gao Ying Zhi
Ministry of Education Key Laboratory of Vegetation Ecology, Institute of Grassland Science, Northeast Normal University, Changchun 130024, China.
Ying Yong Sheng Tai Xue Bao. 2017 Jul 18;28(7):2222-2230. doi: 10.13287/j.1001-9332.201707.040.
Soil salinization and overgrazing are two main factors limiting animal husbandry in the Songnen Grassland. Leymus chinensis is a dominant rhizome grass, resistant to grazing as well as to-lerant to salt stress. Foliar labeled with N-urea was used to study the nitrogen allocation strategy and compensatory growth response to clipping under saline-alkali conditions. The results showed that the total absorbed N allocated to the aboveground part was more than 60%. Compared with the control treatment (no saline-alkali, no clipping), saline-alkali increased the distribution of N by 5.1% in root; the N distribution into aboveground in the moderate clipping and saline-alkali treatment was 11.6% higher than that of the control, exhibiting over-compensatory growth of aboveground biomass and total biomass, however, N allocated to stem base was significantly increased by 9.5% under severe clipping level and saline-alkali addition, showing under-compensatory growth of shoot, root and total biomass. These results suggested that L. chinensis adapted to mode-rate clipping by over-compensatory growth under salt-alkali stress condition. However, L. chinensis would take a relatively conservative growth strategy through the enhanced N allocation to stem base for storage under severe saline-alkali and clipping conditions.
土壤盐碱化和过度放牧是限制松嫩草原畜牧业发展的两个主要因素。羊草是一种优势根茎型禾本科植物，耐放牧且耐盐胁迫。采用 N-尿素叶面标记法研究盐碱条件下羊草的氮分配策略及对刈割的补偿生长响应。结果表明，羊草吸收的氮总量分配到地上部分的比例超过60%。与对照处理（无盐碱、无刈割）相比，盐碱化使根中氮的分配比例增加了5.1%；中度刈割和盐碱化处理下地上部分的氮分配比例比对照高11.6%，地上生物量和总生物量表现出超补偿生长，然而，重度刈割和盐碱化处理下分配到茎基部的氮显著增加了9.5%，地上部、根部和总生物量表现出欠补偿生长。这些结果表明，在盐碱胁迫条件下，羊草通过超补偿生长适应中度刈割。然而，在重度盐碱化和刈割条件下，羊草会采取相对保守的生长策略，通过增加分配到茎基部的氮进行储存。
