中文摘要：

选用不同株型和穗型的3个玉米高产杂交种掖单4号、掖单13和沈单7号,利用植物显微技术与生理生化相结合的方法,比较了不同品种间果穗维管束发育的差异及对种植密度的响应,激素对维管束发育的调控。结果表明,在穗柄（轴）大维管束数、总维管束数、单个大维管束的平均面积、大维管束总面积、维管束总面积上,大穗型品种掖单13和沈单7号显著优于小穗型品种掖单4号;在维管束密度及维管束相对面积上,则紧凑型品种掖单4号和掖单13大于平展型品种沈单7号;密度对果穗维管束的数目、面积及穗粒库容影响显著,不同类型品种间对密度的反应有差异;促进类生长调节剂GA3和6-BA处理能显著增加穗柄内大维管束的数目和面积,显著增加籽粒体积,提高单粒胚乳细胞数和千粒重。

英文摘要：

In addition to sink and source, drain is also an important factor in crop yield forming. Being the organ of drain, vascular bundle （Vb） has been studied widely in recent years. In rice and wheat, researches showed that the number and area of Vb in calm （neck-panicle, branch） were positively correlated to panicle characters; cultivation factors, such as planting density, fertilizer and chemical regulator, affected the development of Vb; the Vb structure was mainly determined by cultivar type. In maize, the related studies, which started later than those in rice and wheat, have focused on the relations between Vb structure and sink capacity of ear and kernel. There are very few reports based on maize cultivar type or genotype. In maize production, vertical-type cultivars are commonly utilized. Researches showed that high yield of vertical-type cultivar is contributed by its sufficient source and large sink, however, the function of drain was seldom mentioned. The present experiments were designed to compare Vb structure and function of maize ear in cultivars with different plant types and ear types. We choose three types of maize hybrids as tested materials, namely Yedan 4, Yedan 13, and Sheridan 7, corresponding to vertical-small-ear type, vertical-large-ear type and horizontal-large-ear type, respectively. The number and area of Vb, phloem, xylem, the number and diameter of vessel were measured using bare-handed sections. The quantity of bleeding sap from ear-stalk and its sucrose content were determined. The effects of planting density and plant growth regulators on Vb structures and function and sink capacity were initially explored. The number of big Vb and total Vb, the average area of single big Vb, total area of big Vbs, total area of all Vbs in ear-pedicel （ear-axis） of Yedan 13 and Shendan 7 （large-ear type） were significandy superior to those of Yedan 4 （smallear type）. The relative area and density of ear Vb of Yedan 4 and Yedan 13 （vertical type） were larger than those of Sher