地下水埋深对玉米生长发育及水分利用的影响

为研究地下水埋深对作物的生长发育及水分利用的影响,选择具有代表性的夏玉米为研究对象,借助地中渗透仪,通过人工控制设置不同地下水埋深（分别设置0.2,0.4,0.6,0.8,1.0和1.2 m）,探讨地下水埋深对不同生育期夏玉米的形态指标、产量、耗水量及地下水补给量的影响,分析不同地下水埋深条件下水分利用率差异.结果表明：地下水埋深对玉米株高的影响不具有统计学意义,而地下水埋深过浅或过深均会明显抑制植株叶面积指数和茎粗的增长（P〈0.05）,地下水埋深0.4 m时叶面积指数和茎粗最大.随作物生育进程,根系数量和根系干质量随地下水埋深增大,先减小后增大.玉米灌浆前,单株根系伤流量随地下水埋深增大而增大,而灌浆前后则无显著影响.地下水位埋深过深或过浅均影响穗长、秃尖长、穗粒数、百粒质量及经济产量.分析表明,0.53 m为当地玉米产量最优地下水位埋深.玉米生长期内0~80 cm土层土壤含水量随着地下水埋深增大而降低,同一地下水埋深处理玉米生育期内土壤含水量变化幅度较小.夏玉米全生育期耗水量、阶段耗水量及耗水强度随地下水位埋深增大而直线减少,回归方程在P〈0.01水平下具有统计学意义;同样夏玉米全生育期地下水补给量、阶段地下水补给量及地下水补给强度随地下水位埋深增大而直线减少,回归方程在P〈0.01水平下也具有统计学意义.玉米水分利用率随地下水埋深增大而增大,地下水埋深1.2 m处理水分利用率最高.研究成果对江淮丘陵区地下水资源利用及评价、玉米高产高效灌溉制度的制订具有实际意义.

Effects of groundwater depth on maize growth and water use efficiency

Groundwater depth has a significant impact on crop growth, development and water use effi- ciency. A typical summer maize crop is taken as trial object, six （0.2, 0.4, 0.6, 0.8, 1.0 and 1.2 m） groundwater depths are set up to investigate its effects on morphological indices, grain yield, water consumption, and groundwater recharge during different growth stages of the summer maize, the diffe- rences in water use efficiency are analyzed too. It is turned out that the groundwater depth shows a littleeffect on plant height, however, either a too shallow or too deep groundwater level can significantly in- hibit the increase in leaf-area index （LAI） and growth of stem diameter （ P 〈 0. 05 ）. The maximum LAI and the biggest stem diameter are reached at 0.4 m groundwater depth. As the crops grow, number of roots and root dry weight decrease initially, and then increase with increasing groundwater depth, a minimum is achievable at a certain depth. Bleeding sap of root system per plant rises with in- creasing groundwater depth before the grain-fill stage, but the bleeding sap is less affected by groundwater depth when the grain fill stage gets started. Furthermore, the groundwater depth also influences ear size, barren tip length, grain number per ear, 100-grain weight, and grain yield substantially. It is observed that 0.53 m groundwater depth is optimal for achieving the maximum maize yield. At crop growth stages, soil water content in 0 -80 cm soil layers is decreased with increasing groundwater depth, but the water content at the same groundwater depth exhibits a slight change during various growth stages. The total water consumption, water consumption at each growth stage, and water consumption intensity are reduced linearly with increasing groundwater depth; their regression equations with groundwater depth have reached extreme significance level （P 〈 0.01 ）. Likewise, the total groundwater recharge, groundwater recharge at each growth stage, and groundwater recharge intensity are also linearly d