[Effects of cultivation environments on Dendrobium catenatum]

The study was aimed to clarify the effect of three cultivation environments on the growth and metabolism of Dendrobium catenatum C13 group. There were three different cultivation conditions including rock epiphytic cultivation, pear epiphytic cultivation and pot cultivation. Morphological characteristics and agronomic characters of D. catenatum were observed and measured. Microstructure, contents of polysaccharide and alcohol-soluble extracts were measured by paraffin section method, phenol-sulfuric acid method and hot-dip method, respectively. The result showed that the cultivation environment significantly affected the growth of D. catenatum, the leaves of D. catenatum that cultivated on the rock and pear were sparse and small, the stems were short and purple and the root system was developed. Compare with potted cultivation, D. catenatum from rock epiphytic cultivation and pear epiphytic cultivation showed the following characteristics in the microstructure: the upper epidermis became thicker, the epidermal hair in the epidermis became denser, stomatal showed smaller and denser, the cell wall of exodermis, endoderm and medulla became thicker, the cell of velamen, exodermis, endoderm and medulla were smaller and arranged more closely, but the cultivation environment did not produce specific tissue structure, mainly changed in the structural parameters of size and quantity. The growth environments also influenced contents of polysaccharides and alcohol-soluble extracts. The dontents of polysaccharides and alcohol-soluble extracts in D. catenatum from rock epiphytic were the highest, reached 37.34% and 11.66%, the second was pear epiphytic, both higher than pot cultivation, alcohol-soluble extracts contents in D. catenatum from rock epiphytic are more complex, which shows that rock epiphytic is conducive to the accumulation of secondary metabolites in D. catenatum.