Abstract:

Plants of the genus Hedychium possess ecological, ornamental, and medicinal values. However, their preference for warm and humid conditions restricts their application in relatively arid environments. To address the above issues, screening of water-saving and drought-tolerant Hedychium germplasm is important. This study aimed to clarify the photosynthetic physiological adaptation mechanism of water-saving and drought-tolerant Hedychium germplasm, thereby providing a theoretical basis for the breeding of high-quality Hedychium varieties, optimization of drought-resistant cultivation modes, and configuration of landscape applications. 10 Hedychium varieties were used as materials, and 12 indicators including leaf area, photosynthetic pigment content, gas exchange parameters, and chlorophyll fluorescence parameters were determined. A comprehensive analysis was conducted using the membership function method of fuzzy mathematics to construct a comprehensive evaluation system for photosynthetic capacity. The results showed significant differences in photosynthetic physiological characteristics among different Hedychium varieties. ‘Milan’ had the largest leaf area (319.65 cm²); ‘Hongtian’e’ had the highest total chlorophyll content (3.11 mg/g); ‘Ya Cheng’ exhibited the highest net photosynthetic rate [4.02 μmol/(m²·s)] and transpiration rate [4.14 mmol/(m²·s)], and maintained stable and high levels of light energy conversion efficiency (0.76-0.80) and PSⅡ potential photochemical activity (Fv/Fo) (3.16-3.93) throughout the day; ‘Qiaoqiao’ had the highest water use efficiency (2.63 μmol/mmol). Correlation analysis revealed that the net photosynthetic rate was extremely significantly positively correlated with stomatal conductance (r=0.78^**) and negatively correlated with intercellular CO₂ concentration (r=-0.49), while there was no significant positive correlation between total chlorophyll content and net photosynthetic rate. Comprehensive evaluation using the membership function method showed that the photosynthetic capacity of the 10 varieties, from strongest to weakest, was in the order: ‘Ai Datou’> ‘Qiaoqiao’> ‘Kuoban’> ‘Yacheng’> ‘Milan’> Hedychium coronarium> ‘Zhuyue’> ‘Xiahong’> ‘Fenyun’> ‘Hongtian’e’. Photosynthetic efficiency was regulated by multiple factors synergistically; ‘Ai Datou’ and ‘Qiaoqiao’ exhibited the optimal photosynthetic capacity and comprehensive adaptability, and could be prioritized as Hedychium germplasm with outstanding water-saving and drought-tolerant potential for application in resource-saving landscape construction. ‘Yacheng’ is suitable for high-yield cultivation in water-sufficient areas, while ‘Fenyun’ and ‘Kuoban’ can be used in the configuration of high-light environments. The results of this study can provide theoretical support for the precise screening of Hedychium germplasm and their landscape application.

Key words: Hedychium, low-maintenance varieties, photosynthetic physiological characteristics, water use efficiency, chlorophyll fluorescence, membership function method