干旱区生态环境知识资源中心

Fourwing saltbush, Atriplex canescens (Pursh) Nun., produces copious quantities of small seed, with minimal nutrient reserves, protected in a hard porous capsule (utricle) that aids in dispersal. At germination, saprophytic fungi simultaneously colonize the utricle, testa, and root cortex cells of the emerging radicles. Seedling vigor was determined by measuring hypocotyl and radicle lengths after germination on minimal carbon or cellulose-supplemented medium. Comparisons were made between seedlings from utricle-excised and intact seed. Comparisons were also made between surface-sterilized and nonsterile excised seed. Minimal growth responses were observed in germinating seedlings from excised seeds on minimal carbon medium. Fungi, utricles, and cellulose supplementation positively affected seedling vigor. The results support a hypothesis that septate fungi recycle utricles and access organic carbon for seedling establishment.