United States Department of Agriculture-Agricultural Research Service, Agricultural Engineering Research Center, Colorado State University, Fort Collins, Colorado 80523.
Plant Physiol. 1986 Jan;80(1):52-8. doi: 10.1104/pp.80.1.52.
The purpose of this study was to characterize leaf photosynthetic and stomatal responses of wheat (Triticum aestivum L.) plants grown under two N-nutritional regimes. High- and low-N regimes were imposed on growth-chamber-grown plants by fertilizing with nutrient solutions containing 12 or 1 millimolar nitrogen, respectively. Gas-exchange measurements indicated not only greater photosynthetic capacity of high-N plants under well-watered conditions, but also a greater sensitivity of CO(2) exchange rate and leaf conductance to CO(2) and leaf water potential compared to low-N plants. Increased sensitivity of high-N plants was associated with greater tissue elasticity, lower values of leaf osmotic pressure and greater aboveground biomass. These N-nutritional-related changes resulted in greater desiccation (lowered relative water content) of high-N plants as leaf water potential fell, and were implicated as being important in causing greater sensitivity of high-N leaf gas exchange to reductions in water potential. Water use efficiency of leaves, calculated as CO(2) exchange rate/transpiration, increased from 9.1 to 13 millimoles per mole and 7.9 to 9.1 millimoles per mole for high- and low-N plants as water became limiting. Stomatal oscillations were commonly observed in the low-N treatment at low leaf water potentials and ambient CO(2) concentrations, but disappeared as CO(2) was lowered and stomata opened.
本研究的目的是描述在两种氮营养条件下生长的小麦（Triticum aestivum L.）叶片光合作用和气孔响应的特征。通过用分别含有 12 或 1 毫摩尔氮的营养液来为生长在温室中的植株施肥，从而施加高氮和低氮条件。气体交换测量不仅表明在充分浇水条件下高氮植株具有更高的光合作用能力，而且与低氮植株相比，CO2 交换率和叶片导度对 CO2 和叶片水势的敏感性更高。高氮植株的敏感性增加与组织弹性增加、叶片渗透压降低和地上生物量增加有关。这些与氮营养有关的变化导致高氮植株在叶片水势下降时发生更大的干燥（相对水分含量降低），并被认为是导致高氮叶片气体交换对水势降低更敏感的重要因素。叶片水分利用效率（以 CO2 交换率/蒸腾作用计算）从 9.1 增加到 13 毫摩尔/摩尔和从 7.9 增加到 9.1 毫摩尔/摩尔，对于高氮和低氮植物，随着水分变得有限。在低氮处理下，在低叶片水势和环境 CO2 浓度下通常观察到气孔振荡，但随着 CO2 降低和气孔打开而消失。
