Chlorophyll Fluorescence Difference Analysis of Four Orchid Species in Dry and Wet Seasons in Dry-Hot Valley of Jinsha River

He Taiping; Li Yuejiong; Hu Xueli; Wang Qiuxia

doi:10.14083/j.issn.1001-4942.2025.01.009

Abstract：In order to study the adaptability of orchids to dry-hot valley habitat,Bletilla striata,Den-drobium wangliangii,Habenaria aitchisonii and Hemipilia cruclata were selected as the research objects in the field environment of dry-hot valley of Jinsha River,and the chlorophyll fluorescence characteristics were ana-lyzed in wet season(July)and dry season(October).The results were as follows:(1)The maximum photo-synthetic efficiency(Fv/Fm)of the four orchids were all lower than 0.8 in both dry and wet seasons,and were lower in dry season than that in wet season,indicating that the four plants were subjected to drought stress for a long time and the degree of stress was stronger in dry season.(2)The Fv/Fm,the actual photo-synthetic efficiency of PS Ⅱ Y(Ⅱ),electron transport efficiency(ETR)and photochemical quenching coeffi-cient(qP)of B.striata in dry season were significantly lower than those in wet season,while there was no significant difference in the four chlorophyll fluorescence parameters of D.wangliangii and H.aitchisonii be-tween dry and wet seasons,indicating that the photosynthetic apparatus of B.striata in dry season was de-stroyed,the electron transport was blocked,the PS Ⅱ reaction center was damaged,showing photoinhibition,while D.wangliangii and H.aitchisonii had stronger abilities in regulating their own PS Ⅱ reaction center from damage.(3)The non-photochemical quenching coefficient(NPQ)of B.striata and D.wangliangii in dry season was significantly lower than that in wet season,which showed no significant difference between dry and wet seasons in H.aitchisonii and H.cruclata,indicating that the PS Ⅱ reaction center of B.striata and D.wangliangii was damaged,and the heat dissipation capacity and light protection ability were decreased under long-term drought stress in the dry season.(4)The ETR and NPQ of H.cruclata in dry season were signifi-cantly higher than those of the other three plants,Y(Ⅱ)was significantly higher than that of B.striata and H.aitchisonii and slightly higher than that of D.wangliangii,and qP was significantly higher than that of B.striata and slightly higher than that of D.wangliangii and H.aitchisonii,indicating that the performance of plant photosynthetic apparatus in H.cruclata was better than that in the other three orchids.In summary,H.aitchisonii performed the most stable under long-term drought stress in the dry-hot valleys,and H.cruclata per-formed better in drought tolerance.