Effects of hybridization on the determinants of photosynthetic capacity in Buddleja F1 hybrids

Abstract

Photosynthetic capacity plays an important role in plant vegetative growth, and is often regarded as a key determinant of adaptability in plant species, including the hybrids. Interspecific hybridizations are common and can easily occur in Buddleja. The F1 hybrid investigated in this study is a newly discovered interspecific hybrid between B. crispa and B. officinalis, and it was found in the Sino-Himalayan region. In this study, the morphological traits, the stoichiometric characteristics and the gas-exchange traits in F1 hybrids and their parents were measured under the cultivation conditions. Buddleja F1 hybrids showed the high leaf mass per area, which was similar to B. officinalis. Although F1 hybrids presented a low light-saturated net photosynthetic rate, they did not reduced carbon cost by increasing the specific leaf area or decreasing the leaf dry mass per unit area. Compared to the parental species, F1 hybrids had low leaf C:N and C:P ratios, C concentration, as well as photosynthetic nitrogen-use efficiency. However, they had a great respiration efficiency through a markedly reduced rate of respiration. Furthermore, F1 hybrids showed similar photochemical efficiency to B. officinalis, which was significantly higher than that in B. crispa. These findings suggest that the F1 hybrids in our study show a high similarity to their parental species in the leaf economic spectrum and photosynthetic capacity.

Keywords

• chlorophyll fluorescence
• effective quantum yield of psii
• light-saturated net photosynthetic rate
• maximum photochemical efficiency of psii
• nonmetric multi-dimensional scaling