Physiological and growth responses to experimental warming in first-year seedlings of deciduous tree species

Authors : Jiae AN, Saerom HAN, Hanna CHANG, Min Ji PARK, Seongjun KIM, Jaehong HWANG, Min Seok CHO, Haegeun CHUNG, Yowhan SON

Pages : 175-182

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Publication Date : 2017-06-01

Article Type : Research Paper

Abstract :Increasing temperature might affect physiological and growth traits of seedlings, which are particularly important for tree survival. This study was conducted to investigate the physiological and growth responses of first-year seedlings to open-field experimental warming during one growing season. Seedlings of three deciduous tree species insert ignore into journalissuearticles values(Fraxinus rhynchophylla Hance, Zelkova serrata insert ignore into journalissuearticles values(Thunb.); Makino, and Quercus variabilis Blume); were warmed with infrared heaters with a mean air temperature difference of 3.07 °C between the treatments. Physiological traits insert ignore into journalissuearticles values(net photosynthetic rate, transpiration rate, stomatal conductance, and total chlorophyll content); were measured in July, September, and October 2014, and growth traits insert ignore into journalissuearticles values(root collar diameter insert ignore into journalissuearticles values(RCD);, shoot length, component biomass, and root mass to stem mass ratio insert ignore into journalissuearticles values(RSR);); were measured in June, August, and October 2014 for harvested seedlings. Net photosynthetic rate, transpiration rate, and stomatal conductance were not affected by the warming treatment, whereas total chlorophyll content increased. Shoot length, leaf biomass, and stem biomass were enhanced under the warming treatment, whereas RCD and root biomass did not differ between the treatments. Thus, relative root growth declined under the warming treatment. It is likely that the elevated temperature provides optimal conditions for the biosynthesis of chlorophyll. Moreover, seedlings allocated more carbon to aboveground growth than to belowground growth when temperatures were elevated. In contrast, net photosynthetic rate, transpiration rate, and stomatal conductance were hindered, failing to increase as an adaptive mechanism to warming-induced water stress. Further studies are needed to elucidate insert ignore into journalissuearticles values(1); the direct effect of a decline in soil moisture, insert ignore into journalissuearticles values(2); why RSR declines to different extents in different species, and insert ignore into journalissuearticles values(3); the relationship between decreased root growth and seedling survival under the warming treatment.
Keywords : Ash, experimental warming, Japanese Zelkova, oriental oak, seedling growth