Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Kamikita, Aomori 039-3212, Japan.
Tree Physiol. 2022 Nov 8;42(11):2294-2305. doi: 10.1093/treephys/tpac072.
Deciduous trees accumulate carbon (C) in woody parts during the growth season which is subsequently used for the initial development and growth of newly formed organs in the following season; however, it is unclear which period during the growth season contributes to C accumulation. Three-year-old potted Malus domestica (apple) trees were grown in controlled growth chambers during the growth season and exposed to 13CO2 in an exposure chamber at seven different periods of the growth season, including vegetative and reproductive growth periods. Approximately half of the trees were harvested in late autumn, and the remaining trees were grown in a field in the following year. The 13C accumulation in the different organs in late autumn, and its concentration in the new aboveground growth during the following growth season, was determined. The concentration of the photoassimilated 13C in woody parts (shoots, trunk, rootstock and coarse roots) in the late autumn was higher in the trees labeled during the period of vigorous vegetative growth than in those labeled during other periods of growth. Furthermore, 13C concentration in the leaves, annual shoots, flower buds and flowers in the following early spring was also high in the trees labeled during this period. The concentration of 13C in the flower buds and flowers was positively correlated with that in the woody parts in the late autumn and old shoots in the following spring. Hence, the seasonal accumulation of photoassimilated C in woody parts in late autumn is related to growth rates during the growth season and its use for the initial development of newly formed organs in the following spring. These results suggest that under non-stressed conditions, C accumulated during the period of vigorous vegetative growth largely contributes to the C reserves that are used for the development of new organs in the following year.
落叶树木在生长季节会将碳（C）积累在木质部分，随后用于下一季新形成器官的初始发育和生长；然而，目前尚不清楚生长季节的哪个时期有助于 C 积累。三年生盆栽苹果树（苹果）在生长季节在受控生长室中生长，并在生长季节的七个不同时期在暴露室中暴露于 13CO2，包括营养生长和生殖生长时期。大约一半的树木在深秋收获，其余树木在次年生长在田间。确定了深秋不同器官中 13C 的积累及其在下一个生长季节新地上生长中的浓度。深秋木质部分（枝条、树干、砧木和粗根）中光合作用同化 13C 的浓度在旺盛营养生长时期标记的树木中高于在其他生长时期标记的树木中。此外，在同一时期标记的树木中，早春叶片、一年生枝条、花蕾和花朵中的 13C 浓度也很高。花蕾和花朵中的 13C 浓度与深秋木质部分和次年早春的老枝条中的浓度呈正相关。因此，深秋木质部分光合作用同化 C 的季节性积累与生长季节的生长速度以及其用于次年新形成器官的初始发育有关。这些结果表明，在非胁迫条件下，营养生长旺盛时期积累的 C 很大程度上有助于为次年新器官的发育提供 C 储备。
