Morphology and photosynthesis of an intergeneric hybrid between Sinocalycanthus chinensis and Calycanthus floridus

Key words: 
• botany /
• Sinocalycanthus chinensis /
• Calycanthus floridus /
• intergeneric hybrid /
• apparent quanta efficiency（AQE） /
• water use efficiency（WUE）

Abstract: We obtained an intergeneric hybrid between female，Sinocalycanthus chinensis，and male，Calycanthus floridus in 2001，in Nanjing botanical Garden Mem. Sun Yat-sen. This hybrid initially flowered in 2006. Differences in（1） flower morphology，（2） fecundity，and（3） photosynthesis and water use efficiency（WUE） between this intergeneric hybrid and its parents were researched in Nanjing in 2006 and 2007. Ecological differences of photosynthesis and water use with S. chinensis between nursery plants and those in an endangered species garden（ESG） were also studied. Results showed that （1） the intergeneric hybrid combined favorable qualities of its parents and had a high ornamental value with intermediate morphological characteristics for flowers-size，color，odor，and perianth arrangement，outer and inner row tepals（amount，size，color，shape，and texture），for stamens （fertile，staminodia，“food body”），and for pistils（style，stigma）. Also，（2） natural fecundity was found in S. chinensis and non-normal fructification in C. floridus with the intergeneric hybrid exhibiting florescence but unfruitful for the two years of this study. Additionally，（3） the intergeneric hybrid was similar to C. floridus in photosynthesis and water use，but without a severe photosynthetic midday-depression or burns on leaves and bracts；in the nursery with natural sunlight，the hybrid showed a strong superiority to S. chinensis. In addition，compared to C. floridus，the hybrid，and S. chinensis in a nursery with natural sunlight，S. chinensis with shading in an ESG expressed a higher apparent quanta efficiency（AQE） and water use effiencyc（WUE） with lower rates of net photosynthesis and transpiration and with no photosynthetic midday-depression. ［Ch，1 fig. 3 tab. 17 ref.］