Abstract: Rhizosheath is an adaptive feature of sandy plant to drought and infertile conditions affected by soil microorganism and moisture. In order to investigate the relationship between rhizosheath formation and root growth at the seedling stage of Kengyilia hirsuta,a two-way ANOVA design was used with two soil treatments (unsterilized and sterilized) and three moisture treatments (10%,25% and 40% of field capacity),respectively. The results showed that:The interaction between sterilization and moisture treatments had highly significant effects (P<0.01) on the root biomass,root-shoot ratio,root length,root surface area,root volume,root forks,root activity,content of abscisic acid,and content of gibberellin of K. hirsuta. Under the soil sterilization treatment,along with 10% soil moisture treatment,the root biomass increased significantly (P<0.05);the root length,root surface area and root volume under 25% moisture,the root activity under 40% moisture (P<0.05) significantly increased as well;and the content of abscisic acid,indole-3-acetic acid and gibberellin were significantly higher for different moisture treatments (P<0.05). Under moisture treatments,the rhizosheath weight,root activity and cytokinin content of 10% moisture were the lowest (P<0.05),the rhizosheath weight of 25% moisture was the highest (P<0.05),and the cytokinin content of 40% moisture was the highest. When soil was not sterilized,the direct effect of root activity on rhizosheath weight was the largest. The direct and indirect effects of indole-3-acetic acid on rhizosheath weight were the greatest after soil sterilized. This study could provide a reference for revealing the formation mechanism of rhizosheath.

Key words: Kengyilia hirsuta, Rhizosheath, Soil sterilization, Moisture

摘要： 根鞘是沙地植物根系对干旱和贫瘠条件的适应性特征,受土壤微生物和水分影响。为探究糙毛以礼草苗期根鞘形成与根系生长的关系,采用双因素设计,分别设置2个土壤处理(未灭菌和灭菌)和3个水分处理(田间持水量的10%,25%和40%)。结果显示:灭菌与水分的互作对根系生物量、根冠比、根长、根表面积、根体积、分叉数、根系活力、脱落酸和赤霉素均有极显著影响(P<0.01)。土壤灭菌处理后,10%水分的根系生物量显著增加(P<0.05),25%水分的根长、根表面积和根体积显著增加(P<0.05),40%水分的根系活力显著增加(P<0.05),不同水分处理的脱落酸、吲哚乙酸、赤霉素含量均显著升高(P<0.05)。不同水分处理下,10%水分的根鞘重、根系活力和细胞分裂素含量最低(P<0.05),25%水分的根鞘重最大(P<0.05),40%水分的细胞分裂素含量最高。土壤未灭菌时,根系活力对根鞘重的直接作用最大;土壤灭菌处理后,吲哚乙酸对根鞘重的直接和间接作用均最大。本研究可为揭示根鞘的形成机制提供参考。

关键词: 糙毛以礼草, 根鞘, 土壤灭菌, 水分