Centre for Agrobiological Research, P.O. Box 14, 6700 AA, Wageningen, The Netherlands.
Photosynth Res. 1987 Jan;11(3):253-64. doi: 10.1007/BF00055065.
Potatoes (Solanum tuberosum L., cv. Bintje) were grown in a naturally lit glasshouse. Laboratory measurements on leaves at three insertion levels showed a decline with leaf age in photosynthetic capacity and in stomatal conductance at near saturating irradiance. Conductance declined somewhat more with age than photosynthesis, resulting in a smaller internal CO2 concentration in older relative to younger leaves. Leaves with different insertion number behaved similarly. The changes in photosynthesis rate and in nitrogen content with leaf age were closely correlated. When PAR exceeded circa 100 W m(-2) the rate of photosynthesis and stomatal conductance changed proportionally as indicated by a constant internal CO2 concentration. The photosynthesis-irradiance data were fitted to an asymptotic exponential model. The parameters of the model are AMAX, the rate of photosynthesis at infinite irradiance, and EFF, the slope at low light levels. AMAX declined strongly with leaf age, as did EFF, but to a smaller extent. During drought stress photosynthetic capacity declined directly with decreasing water potential (range -0.6 to -1.1 MPa). Initially, stomatal conductance declined faster than photosynthetic capacity.
土豆（Solanum tuberosum L.，cv. Bintje）在自然采光的玻璃温室中种植。对三个插入水平的叶片进行实验室测量表明，随着叶片年龄的增长，光合能力和近饱和辐照度下的气孔导度下降。与光合作用相比，导度随年龄的增长下降得更多，导致较老叶片的内部 CO2 浓度相对较小。具有不同插入数的叶片表现相似。光合作用速率和氮含量随叶片年龄的变化密切相关。当 PAR 超过 100 W m(-2) 时，光合作用和气孔导度的速率按比例变化，如内部 CO2 浓度恒定所示。光合作用-辐照度数据拟合到渐近指数模型。模型的参数是 AMAX，无限辐照度下的光合作用速率，以及 EFF，低光水平下的斜率。AMAX 随叶片年龄的增长而强烈下降，EFF 也是如此，但程度较小。在干旱胁迫下，光合能力随水势的降低而直接下降（范围为-0.6 至-1.1 MPa）。最初，气孔导度的下降速度快于光合能力。
