休牧时期对高寒草甸垂穗披碱草种子大小和萌发特性的影响

【目的】确定有利于垂穗披碱草（Elymus nutans）种子生长和提高种子萌发特性的休牧时期。 【方法】在东祁连山天祝高寒草甸设置土壤解冻临界期—牧草枯黄期（RP1）、土壤解冻后期—牧草枯黄期（RP2）、牧草返青初期—牧草枯黄期（RP3）、牧草返青后期—牧草枯黄期（RP4）和当地传统休牧（优势牧草高 5 cm—牧草枯黄期）（RP5）5 个休牧时期，研究不同时期休牧对垂穗披碱草种子大小、萌发特性及二者之间相关关系的影响。【结果】 RP1 休牧垂穗披碱草种子面积、周长、长宽比和长度均最大，其中面积、周长和长度较 RP5 休牧分别增加了 15. 14%、10. 22% 和 11. 97%。RP4 休牧千粒重显著高于 RP1、RP2 和 RP5。与 RP5 相比，提前休牧显著提高了垂穗披碱草种子的发芽势、发芽指数、发芽率、芽长和活力指数 ，RP1、RP2、RP3 和 RP4 休牧种子的发芽率较 RP5 分别提高了 84. 86%、121. 23%、 127. 27% 和 127. 27%。相关性分析表明，垂穗披碱草种子千粒重与发芽势、芽长呈极显著正相关。【结论】 RP1 休牧可提高垂穗披碱草种子面积、周长、长宽比和长度，且种子具有较好的萌发特性，有利于保护和恢复垂穗披碱草。

Effects of rest grazing periods on seed size and germination characteristics of Elymus nutans in alpine meadow

【Objective】 The objective of this study was to determine the rest grazing period conducive to the seed size and germination characteristics of Elymus nutans.【Method】 Five rest grazing periods were set up in Tianzhu alpine meadow of east Qilian Mountain，including the critical period of soil thawinggrass withering period （RP1），the late period of soil thawinggrass withering period （RP2），the initial period of grass regreeninggrass withering period （RP3），the late period of grass regreening—grass withering period（RP4） and the local traditional rest grazing（when the dominant plant height was 5 cm—grass withering period）（RP5）. The effects of rest grazing in different periods on the seed size and germination characteristics of E. nutans and the relationship between them were studied.【Result】 The seed area，perimeter，length width ratio and length were the largest in RP1，and the area，perimeter and length were increased by 15. 14%，10. 22% and 11. 97%，respectively，compared with RP5. The thousand-grain weight of RP4 was significantly higher than that of RP1，RP2 and RP5. Compared with RP5，early rest grazing significantly improved the germination potential，germination index，germination percentage，bud length and vigor index. The germination percentages of RP1，RP2，RP3 and RP4 were 84. 86%，121. 23%，127. 27% and 127. 27% higher than RP5，respectively. Correlation analysis showed that thousand-grain weight was significantly positively correlated with germination potential and bud length.【Conclusion】 RP1 rest grazing could improve the seed area，perimeter，length width ratio and lengthof E. nutans，and the seeds have better germination characteristics，which is conducive to the protection and restoration of E. nutans vegetation.