红砂幼苗根系形态特征对降水格局变化的响应

Response of root morphology to precipitation change in Reaumuria soongoricaseedlings

以西北荒漠生态系统典型植物红砂一年生幼苗为研究对象,利用塑料遮雨棚,研究了人工模拟不同降水格局下红砂幼苗根系形态的变化特征。结果表明,(1)降水量一定时延长降水间隔时间,红砂幼苗根系各指标均呈增加趋势,总根长、总根体积和根系生物量增加最为显著,分别为39.22%、62.50%和63.20%。(2)降水间隔时间延长至10d时,降水量增加30%对幼苗根系各指标均有促进作用,且对总根体积和根系生物量的作用尤为突出,使其分别显著增加116.27%和224.40%(P<0.01)。(3)在自然降水条件下延长降水间隔时间,比根长和比表面积达到最大值,幼苗其他指标则无显著变化,说明幼苗对此水分条件的适应能力最强。(4)相关分析表明,不同降水格局条件下,红砂幼苗各形态指标间存在相关关系,但水平各异。总根长、总根表面积、总根体积、根平均直径及根系生物量之间呈显著正相关,且相关系数接近0.5,说明红砂幼苗根系具有较强的形态可塑性。

To investigate the effects of precipitation pattern change on root morphological characteristics of Reaumuria soongorica seedlings in arid and semi-arid areas, a controlled experiment with two factors： precipitation [natural precipitation as control （W）; W plus 30% （W＋）; W minus 30% （W-） and precipitation interval （5 days, T; 10 days, T＋）], during the growing season. Results; （1）： Root morphological indices showed an increasing trend with increasing precipitation with total root length, total root volume and root biomass increasing by 39.2%, 62.5% and 63.2%, respectively. （2）： Extended precipitation time interval promoted seedling root indices with increased precipitation. When precipitation interval was 10 days and rainfall was increased 30%, the total root volume and root biomass were increased by 116.3% and 224.4% respectively （P〈0.01）. （3）： Apart from specific root length and specific root area which were highest under natural precipitation and 10 day interval, remaining indices were not affected by the irrigation treatments. （4）： Correlation analysis showed that the relationship between different indices differed under different precipitation patterns; total root length, total root surface area, total root volume, mean root diameter and root biomass were significantly positive correlated （r=0.5）, indicating that R. soongorica seedling root systems possessed strong morphological plasticity. Both irrigation quantity and time interval significantly affected root morphology and there was an interaction between them, but the effect of rainfall was more important. R. soongorica seedlings showed strong morphological plasticity, being able to adapt to environmental stress by changing root morphological characteristics.