Kitaoka Satoshi, Laiye Qu, Watanabe Yoko, Watanabe Makoto, Watanabe Toshihiro, Koike Takayoshi
Faculty of Earth Environmental Sciences, Hokkaido University, Sapporo 060-0810, Japan.
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Plants (Basel). 2020 Sep 28;9(10):1278. doi: 10.3390/plants9101278.
Japanese larch ( = ) is often characterized by its high growth rate with heterophyllous shoots, but the functional differences of heterophyllous shoots still remain unclear. Recently, abrupt high temperature and drought during spring induced high photosynthetic rate via change in leaf morphology of the deciduous habit. In order to reveal the photosynthetic characteristics of both short and long-shoot needles of sunny canopy of the larch trees using a canopy tower, we calculated the seasonal change of gas exchange characters and leaf mass per area (LMA) and foliar nitrogen content (N) of heterophyllous needles: short and long-shoot needles over 3 years. No marked difference in light-saturated photosynthetic rates (P) was observed between short and long shoots after leaf maturation to yellowing, although the difference was obvious in a specific year, which only shows that seasonal change in temperature and soil moisture determines the in situ photosynthetic capacity of needles. The large annual and seasonal variations in P in both shoots were found to be mainly determined by climatic variations, while shoot types determined the strategy of their photosynthetic N utilization as well as the stomatal regulation.
日本落叶松（=）通常以其具有异型枝的高生长速率为特征，但异型枝的功能差异仍不清楚。最近，春季突然出现的高温和干旱通过落叶习性叶片形态的变化诱导了较高的光合速率。为了利用树冠塔揭示落叶松阳光树冠层短枝和长枝针叶的光合特性，我们计算了3年中异型针叶（短枝和长枝针叶）气体交换特征、单位面积叶质量（LMA）和叶片氮含量（N）的季节变化。叶片成熟至变黄后，短枝和长枝的光饱和光合速率（P）没有明显差异，尽管在特定年份差异明显，这仅表明温度和土壤水分的季节变化决定了针叶的原位光合能力。发现两个枝条中P的年度和季节变化较大主要由气候变化决定，而枝条类型决定了其光合氮利用策略以及气孔调节。
