关键词: 蕾期, 干旱胁迫, 切花质量, 百合, 生理变化

Abstract: Epiphytic bryophytes on trees are a useful indicator of air pollution and they provide habitats for a large number of diatoms. Until now, little knowledge is available about these diatoms and their autoecology. In this paper, twentytwo epiphytic bryophyte samples on trees from the main parks and campuses in Wuhan City and four samples from Dajiuhu National Natural Reserve (for comparison) were collected for diatom analysis, in combination with tree and bryophyte identifications. In total, 13 genera and 73 species of diatoms were identified, which were dominated by three Pennatae taxa, i.e. Luticola mutica, Pinnularia borealis and Hantzschia amphioxys. Seven samples had more than 10 diatom species within each sample, indicating high diatom richness in epiphytic bryophytes. Three clusters were identified by principal component analysis and clustering analysis, including one dominated by L. mutica, a second with H. amphioxys and Humidophila contenta codominated assemblages, and a third dominated by the diatom P. borealis. All of these dominant diatom species are cosmopolitan droughttolerant species. The high abundance of droughttolerant species was mainly responsive to dry conditions on tree bark. Twentysix samples were divided into different groups according to their host tree species and bryophyte species and locations, respectively. The ANOSIM analysis revealed that there was no parasitehost relationship between diatoms and bryophytes, but tree species might influence diatom composition. Diatom communities in Wuhan City were significantly different from those in Dajiuhu National Natural Reserve. The results revealed the characteristics of epiphytic diatom composition on epiphytic bryophytes, thus improving our knowledge about the biodiversity of terrestrial diatoms and their potential as an environmental indicator.

Key words: bud stage, physiological change, lily, quality of cut flower., drought stress