Studies on the characteristics of photosynthesis and dry matter production in wheat varieties with different P efficiency

Chinese. 通过对不同磷效率品种的光合碳同化与物质生产特性研究，阐明磷高效小麦品种高效吸收磷素的生理机制。以具有典型特征的不同磷效率小麦品种为材料，研究了丰、缺磷条件下的光合生理参数、碳酸酐酶活性和RuBPCase活性。缺磷条件下，各测定时期的叶绿素含量（Chl）、气孔导度（gs）、叶肉导度（gm）、碳酸酐酶活性（CA）和光合速率（Pn）以及可溶蛋白含量（SP）和RuBPCase活性均大致以磷高效品种（H）最高，中效品种（M）次之，低效品种（L）最低；不同磷效率品种各测试时期的LAI和作物生长率（CGR）、净同化率（NAR）和光合势（PP）也以H最高，M次之，L最低。磷胁迫条件下，H较高的Pn是由于其具有较强的光反应活性、较强的CO2传输能力和较高的暗反应效率综合作用的结果；其光合碳同化特性和物质生产能力的相对改善，主要是由于植株磷吸收数量较多，使细胞内部磷胁迫程度相对较低及由此导致的光合机构功能相对提高所致。

English. In order to elucidate the Physiological Mechanisms in wheat varieties with different P efficiency, the characteristics of photosynthesis and dry matter production with different P efficiency were studied. Parameters of photosynthesis, carbonic anhydrase (CA) activities and RuBPCase activities were studied in wheat varieties with different P efficiency. Under P-deficient condition, the chlorophyll contents (Chl), stomatal conductances (gs), mesophyll conductances (gm), carbonic anhydrase (CA) activities, photosynthetic rate (Pn), soluble protein contents (SP) and RuBPCase activities at the jointing stage, spiking stage and mid-filling stage were of the best in the varieties with high-P efficiency (H), then in the varieties with mid-P efficiency (M), and the worst in the varieties with low-P efficiency (L). The leaf area index (LAI), canopy growth rate (CGR), net assimilation rate (NAR) and photosynthetic potential (PP) were also the highest in H, then in M, and the lowest in L. Under P-deficient condition, the high Pn in H was due to the relative improved coordination among the photoreaction, conductance of CO2 at air phase and liquid phase, and dark reaction in the chloroplast. The relative improvement of the photosynthesis and dry matter production in the varieties with high-P efficiency under the Pi-deficient condition possibly resulted from the relative Pi acquisition in the plant, lessened the stressed P limitation in the cell and further improve the function of the photosynthetic organ.