中文摘要：

应用徒手切片和石蜡切片，系统观察了玉米穗、粒发育期间穗轴及小穗柄内维管束的分化、发育和联络，测量了不同维管束的横截面积；收集测定了果穗发育过程中果柄伤流液；探讨了穗、粒维管束的发育与穗粒库容的关系。结果表明，果穗内维管束联络系统的分化发育与穗分化相一致；穗柄-穗轴-籽粒的维管联络在双小穗期初步建成，至穗分化结束时完善成熟；不同穗位、粒位的果穗维管束数目、面积上存在显著差异，下位退化穗和果穗顶部的维管束发育差；穗柄与穗轴内的大维管束数、单个大维管束的平均面积、大维管束面积、维管束总面积与穗粒数、籽粒干重、籽粒体积间存在显著正相关关系；籽粒发育期间，穗柄伤流量及输送效率的变化趋势与籽粒干重的增长趋势一致。

英文摘要：

In recent years, most works about grain yield forming focused on sink-source relationship, and set up a series of theory and technique of high yield using in crop production. There were few studies on sink-flow, which is important for grain yield forming. The spike vascular bundle is an essential organ of flow. The objective of this study was to examine the vascular bundles structure of various spikes and different parts of spike in maize, and to reveal the relationship between development of spike vascular bundles and spike-grain sink. Hybrid maize Yedan 4 was used to observe the differentiation, development and contact of vascular bundles in ear-axis and ear-stalk during ear and grain development using hare-handed sections and paraffin sections. The number and transverse section area of vascular bundle were measured. The bleeding sap from ear-stalk were collected and determined in different development stages. The relationship between development of spike vascular bundle and sink capacity of ear and kernel in maize was explored. The main results were as follows： The development of spike vascular bundle system and differentiation of ear were synchronous （plate Ⅰ , 1 - 6） ; the vascular bundle system was constructed in stalk of ear-axis in period of pair spikelet differentiation （plate Ⅰ , 3） and fully developed in late period of ear-differentiation （Plate Ⅰ , 5）. The transverse vascular bundles were differentiated from stem node of spike which pointed to young ear-pedicel （ Fig. 1 ）. There were two types of vascular bundle, the netty and the lengthwise in spike-stalk （Fig. 2）. The former extended into bract and the latter into earaxis. The branches of vascular bundle in ear-axis lengthened into spikelet and formed pedicel vascular bundles （Fig. 3 ）.The spike vascular system was composed of the stem-node vascular bundles, the ear-stalk vascular bundles, the ear-axis vascular bundles and the transverse brunches of ear-axis vascular bundle to ensure the nutrient transport easily and