孕穗期渍水对不同小麦品种根系生长和籽粒产量的影响

为给长江中下游地区小麦高产耐渍品种选用提供参考，以小麦品种扬麦25、扬麦24、宁麦13和宁麦9号为材料，分析了孕穗期连续10 d渍水处理对小麦叶面积和光合速率、地上部干物质积累、籽粒产量及其结构和不同土层（0~100 cm）根系干重的影响。结果表明，与对照（正常水分）相比，渍水处理显著降低小麦籽粒产量，降幅12%~31%，穗粒数和千粒重的减少是减产的主要原因。相比其他品种，渍水后扬麦25产量降幅小，产量构成较协调，受渍水影响轻。渍水处理显著减少小麦开花期和成熟期不同土层根系干重，其中对下层根系的影响大于上层根系；渍水也显著降低乳熟期倒三叶面积、倒二叶和倒三叶净光合速率，明显抑制成熟期地上部各器官和花后光合物质积累。在对照条件下，扬麦25的根系干重在开花期与其他品种相近，成熟期的0~20和80~100 cm土层根系干重则较高；在渍水条件下，扬麦25能在花后维持较高的上层根系生物量，成熟期的0~60 cm土层根干重占总根干重比例较高。不同水分处理下，扬麦25均具有面积大的旗叶且高的净光合速率，花后维持较久的上三叶绿色面积和积累更多的光合产物。因此，小麦花后根系生物量保持稳定（尤其是表层根系），绿叶面积较大且衰减慢（尤其是旗叶），有助于增强小麦花后光合物质积累能力，促进籽粒灌浆和单穗高产稳产，这可作为高产耐渍品种的筛选依据。

Effects of Waterlogging at Booting Stage on Root Growth and Grain Yield of Different Wheat Cultivars

To provide references for the selection of high-yield and waterlogging-resistant wheat cultivars in the middle and lower reaches of the Yangtze River, Yangmai 25, Yangmai 24, Ningmai 13, and Ningmai 9 were selected as materials to study the effects of the 10 days waterlogging treatment at booting stage on leaf area, leaf photosynthetic rate, aboveground dry matter accumulation, grain yield and its components, and root dry weight in different soil layers (0-100 cm). The results showed that the waterlogging treatment significantly decreased grain yield by 12%-31%, compared with the control treatment, mainly due to the reduction of grains per spike and 1 000-grain weight. Compared with other cultivars, Yangmai 25 showed the least reduction in grain yield under the waterlogging treatment. The grain yield components of Yangmai 25 were more coordinated and slightly affected by waterlogging. Waterlogging significantly reduced root dry weight in different soil layers at anthesis and maturity stages, and the lower roots were affected more greatly than the upper roots. The green leaf area of the top third leaf and net photosynthetic rate of the top second and third leaves at the milk-ripening stage were significantly decreased by waterlogging. The accumulation of photosynthate in shoot organs at maturity and after anthesis was also markedly inhibited. Under the control conditions, the root dry weight of Yangmai 25 was similar to that of other cultivars at anthesis stage, but it showed significantly higher root dry weight in 0-20 cm and 80-100 cm soil layers at maturity stage. Compared with other cultivars, Yangmai 25 maintained more root biomass in the upper layer after anthesis and showed a significantly higher proportion of 0-60 cm root dry weight to total root weight at maturity stage under the waterlogging conditions. Besides, Yangmai 25 had a larger flag leaf area and higher net photosynthetic rate, maintained a longer duration of the top three green leaf area, and accumulated more photosynthates after anthesis under different waterlogging treatments. Therefore, stable root growth at post-anthesis, especially for the surface roots, and large green leaf area with slow decay, especially for the flag leaf, contributes to a strong post-anthesis photosynthetic accumulation level and high and stable spike yield, which can be used as the selection basis of high-yield and waterlogging-tolerance cultivars.