野生老芒麦苗期耐旱性品种筛选及鉴定

根据老芒麦(Elymus sibiricus)苗期对干旱胁迫的响应,筛选出适宜在半干旱地区生长的老芒麦,为青藏高原半干旱地区的栽培草地建植、草地补播改良和草原生态恢复提供依据.选取青海省互助县、门源县、大通县和刚察县地区不同生境的19份野生老芒麦为研究材料,同时以青牧1号老芒麦(Elymus sibiricus'Q i n g m u N o.1')和川草2号老芒麦(E.sibiricus'C h u a n c a o N o.2')作为参比材料,采用盆栽控水法(土壤相对含水量为田间持水量的45％～50％)模拟典型干旱胁迫环境,定株测定了老芒麦的表型和生理指标,并通过模糊数学隶属函数法对野生老芒麦和栽培种老芒麦苗期耐旱性进行了综合评定.结果表明,随着干旱胁迫天数的增加,老芒麦材料株高、相对生长速率、单叶面积增长减缓,相对存活率、叶绿素含量持续下降,根系干物质积累率、相对电导率值则不断上升.老芒麦株高、叶面积、根系干物质积累等形态的可塑性是苗期老芒麦适应干旱环境的重要方式.供试的21份老芒麦材料中,大通县的15-195老芒麦苗期耐旱性最强,属Ⅰ级强抗.

Screening and identification of drought tolerance varieties of wild Elymus sibiricus at seedling stage

Elymus sibiricus selections suitable for growing in semi-arid areas were screened out according to their response to drought stress at the seedling stage; this provides the basis for artificial grassland construction, grassland replanting improvement and grassland ecological restoration in semi-arid areas of Qinghai Tibet Plateau. This study selected material from 19 wild Elymus sibiricus provenances from different habitats in Huzhu County, Menyuan County, Datong County, and Gangcha County of Qinghai Province. Taking Elymus sibiricus ‘Qingmu No.1’ and E. sibiricus ‘Chuancao No. 2’ as reference materials, the selections were cultivated in pots in a simulated typical drought stress environment (soil relative water content 45%～50% of field water capacity). Phenotypic and physiological indexes of Elymus sibiricus were determined in fixed plants. The drought tolerance of the wild and cultivated Elymus sibiricus selections at the seedling stage were comprehensively evaluated by the subordinate function method. The results were as follows: With increased numbers of drought stress days, the plant height, leaf area, dry matter accumulation percentage and chlorophyll content in the control group showed an increasing trend, while the percentage root dry matter accumulation and relative electrical conductivity showed a decreasing trend. Compared with the control group, the plant height, relative growth rate, relative survival percentage and chlorophyll content of Elymus sibiricus selections in the treatment group decreased continuously with increased numbers of drought stress days, while the relative conductivity value increased continuously. The morphological plasticity of plant height, leaf area and root system dry matter accumulation is an important way for Elymus sibiricust to adapt to drought environments at the seedling stage. Among the 21 Elymus sibiricus materials tested, the 15-195 Elymus sibiricus selection from Datong County had the strongest drought resistance and was notably better than the other materials.