毛苔草地下构件对不同水文情势和水文经历的生长响应

Growth responses of belowground modules of Carex lasiocarpa to different water regimes and water experiences.

通过幼苗移植水位控制试验,研究了三江平原毛苔草地下构件生长对不同水文情势及水文经历的响应.结果表明:毛苔草地下构件生长对不同水文情势的响应具有显著差异;在毛苔草生长旺盛期,其根茎及不定根长度随淹水程度的增加而缩短,到生长末期,干旱处理下毛苔草根茎及不定根长度仍然最大,但在持续淹水处理下,毛苔草根茎及不定根长度由旺盛期到末期的增幅最大,说明生长季内稳定的低水分条件对毛苔草根茎及不定根的生长较为有利;在生长旺盛期和末期,干湿交替处理下毛苔草根茎、不定根及地下总生物量均最高;不同水文经历下,以前期干湿交替、后期干旱处理下毛苔草根茎的鲜、干质量最大,而生长季内始终经历干湿交替处理下毛苔草的不定根及地下总生物量最大.比较地下构件在生物量积累中所占的比重发现,各水文情势下,生长季末期毛苔草总生物量明显向根茎转移;整个生长季内,干旱处理下毛苔草根茎生物量的比重明显高于其他处理.在淹没水文情势下,毛苔草地下构件生长缓慢,但淹没抑制消除后,其生长过程可通过根茎萌发得以延续.

With seedling＇ s transplanting experiment under different water levels, this paper studied the growth responses of belowground modules of Carex lasiocarpa to various water regimes and water experiences in Sanjiang Plain. The results showed that the belowground modules of C. lasiocarpa had significantly different responses to water regimes. At thriving stage, the length of rhizome and adventitious root decreased with increasing water level, and until later growth stage, the maximal value still appeared under drought condition. However, under dry-wet alternate condition, the length of rhizome and adventitious root increased most from thriving stage to the end, indicating that stable and lower water level could improve the growth of rhizome and adventitious root. The biomass of rhizome, adventitious root, and belowground part were maximal under dry-wet alternate condition at both growth stages. For those with different water experiences, the ones undergoing alternate con- dition in early growth season and then drought had maximal rhizome biomass, and the others under sustained alternate condition had maximal adventitious root and belowground biomass. More biomass was distributed to rhizome in the later growth season under various water regimes. The percentage of rhizome in total biomass was significantly higher under drought condition than under other water conditions through the growth season. Besides, C. lasiocarpa grew slowly when submerged, but could recover through rhizomatic reproduction after the stress disappeared.