华石斛假鳞茎形态性状与活性成分季节性动态研究OA

The tropical montane cloud forest environment is characterized by low temperatures,high humidity and strong seasonal fluctuations.The mechanisms by which these conditions influence the morphological development and secondary metabolism of endangered epiphytic orchids remain unclear.Taking Dendrobium sinense,an epiphytic spe-cies in the tropical cloud forest of Bawangling,Hainan,as the research object,this study systematically investigated the seasonal dynamics of its pseudobulb morphological traits(number and length)and the contents of major active compo-nents(crude polysaccharides,total flavonoids and total phenolics).Key environmental drivers affecting its growth were identified,and the optimal harvest period was comprehensively evaluated.The results showed that the number and length of D.sinense pseudobulbs exhibited significant seasonal fluctuations,characterized by rapid growth in the early rainy season and conservative morphology during the dry season.Morphological growth peaked in autumn,while the accumulation of active components was asynchronous with morphological growth.Storage substances(crude polysac-charides)reached the peak earlier than defensive substances(total flavonoids and total phenolics).Crude polysaccharide content peaked in December[(13.14±0.94)mg/g],whereas total flavonoids[(13.05±0.84)mg/g]and total phenolics[(11.27±0.25)mg/g]reached the highest levels in February.Environmental fluctuations were the key drivers of pseudobulb morphological growth,with average humidity,temperature variance and humidity variance having the sig-nificant effects:average humidity was positively correlated with pseudobulb length,while temperature variance nega-tively affected pseudobulb number,and humidity variance negatively impacted pseudobulb length.Principal component analysis indicated that pseudobulb length during the senescence period,length during the reproductive period,and crude polysaccharide content were the top three contributing quality indicators.Comprehensive evaluation showed that Octo-ber achieved a relatively optimal balance between morphological traits and active component accumulation,making it the most suitable harvest period for D.sinense.This study reveals the seasonal dynamics patterns of morphological de-velopment and active component accumulation in endangered epiphytic plants under tropical cloud forest conditions,providing a scientific basis for the conservation and sustainable utilization of D.sinense resources.