古尔班通古特沙漠南缘32种藜科植物种子萌发策略初探

对古尔班通古特沙漠南缘32种藜科植物的萌发特性（萌发率、萌发开始时间、平均萌发时间和萌发持续时间）进行研究,以探讨藜科植物的不同萌发对策及其生态适应意义。结果表明,32种植物萌发率呈双峰型,其中萌发率大于80%,或小于20%的种占大多数;萌发开始时间呈单峰型,28种植物在1~3 d内开始萌发;平均萌发时间也呈单峰型,平均萌发时间小于5 d的植物21种,最大的为杂配藜（23.7 d）;萌发持续时间种间差异较大,其中15种植物萌发持续时间小于15 d,10种植物持续时间在15~30 d,5种植物大于30 d。主成分分析和聚类分析结果表明,32种植物可划分为4种萌发类型:爆发型、过渡型、缓萌型和低萌型。以上结果揭示出32种藜科植物种子萌发策略不尽相同,表现为机会主义萌发策略、下注萌发策略和谨慎萌发策略,这与植物所处土壤盐渍化程度存在差异有关。此外,Log尺度下32种藜科植物种子大小及其变异范围较小（10-2~101）,暗示多数藜科植物多为小种子,其容易沿缝隙进入土壤形成短暂或永久种子库,这也是沙漠植物生存策略的重要一环。

Seed Germination Strategies of 32 Chenopodiaceae Species on the Southern Gurbantunggut Desert

In order to determine seed germination strategies and ecological significance of Chenopodiaceae species,seed germination characteristics(germination percentages,germination beginning days,germination periods and mean germination time(MGT) of 32 Chenopodiaceae species from the south edge of Gurbantunggut Desert were studied.Seeds of each species were incubated with alternating temperature regime of 25 ℃ in light for 12 h and 10 ℃ in dark for 12 h,simulating natural conditions during the spring germination period.Seed germination was monitored every 24 h for 60 days.Results showed that germination percentages of 32 species displayed a bimodal distribution,and the species with germination percentage exceeding 80%(25%) and less than 20%(31.3%) were most;germination beginning days displayed a skewness toward short periods,and 28 species began to germinate within 1～3 d(87.5%);MGT was also skewed toward short periods,and 21 species showed MGT less than 5 d(65.6%),and Chenopodium hybridum had maximal MGT(23.7 d);germination period was different among 32 species,and 15 species was less than 15 d,10 species was in 15～30 d,and 5 species exceeded 30 d.Principal component analysis and clustering analysis showed that the 32 Chenopodiaceae species can be divided into four main germination patterns: rapid germination,transitional germination,slow germination and low germination.The results showed that 32 Chenopodiaceae species had different germination strategies,for example,the "opportunism" germination strategy of rapid germination species,the "caution" germination strategy of transition germination species and slow germination species,and the "bet hedging" germination strategy of low germination species,which were associated with soil salinization.Moreover,seed mass and its variation were small in logarithm scale(10-2～101),which implied that Chenopodiaceae species could hold a transient or long-living seed bank.