不同干旱胁迫方式对小麦水分关系和光合作用的影响

Effect of Different Types of Drought Stress on Water Relations and Photosynthesis in Wheat

离体气干使小麦叶片很快遭受水分胁迫,叶片不产生渗透调节作用,水势和膨压降低较快,从而使叶片净光合率(Pn)、气孔导度(Gs)和叶肉CO_2导度(G’m)迅速降低;土壤干旱下,叶片水势降低较缓慢,并产生不同程度的渗透调节作用,使膨压得到部分维持,Pn、Gs和Gm’降低幅度减小.两种方式干旱胁迫下,陕合六号叶片持水力和渗透调节大于郑引一号,Pn、Gs和G’m都明显高于郑引一号.因此,陕合六号小麦有较强的耐旱性.

Detached leaves in air caused quickly water stress, osmotic adjustment of the leaves were not observed and water potential (ψw) and turgor potential (ψ P) of leaves decreased rapidly, therefore, the net photosynthetic rate (Pn) , stomatal conductance (Gs) and mesophylic conductance to CO2 (Gm) depressed on a large scale in short time. In contrary, soil drought caused leaves producing osmotic adjustment in varying degrees, the water potential decreased more slowly, turgor potential was keeped to some extent, Pn, Gs and G'm decreased slowly. Under two types of drought stress, leaves of Shanhe No. 6 had greater drought tolerance than that of Zhengyin No. 1 due to their stronger water holding capacity and greater osmotic adjustment. Thus, the depression of Pn, Gs and G'm of Shanhe No. 6 leaves was smaller than that of Zhengyin leaves.