中国3个主要梨砧木资源木质部导管分子结构及分布比较

采用组织离析法、石蜡切片法和显微照相技术,观测了山梨(Pyrus ussuriensis)、杜梨(P.betuleafolia)和豆梨(P.calleryana)3种我国最主要梨属砧木茎干部位导管分子结构及分布。结果表明,3种梨砧木导管分子结构在侧壁次生增厚和木质化的方式、纹孔式、主要穿孔板类型,以及端壁倾斜、尾有无、尾长短分布趋势基本一致,但山梨、杜梨复穿孔板比例、两端端壁倾斜比例高于豆梨。豆梨导管分子直径显著高于山梨和杜梨;山梨和杜梨导管频率显著高于豆梨。木质部比导率测定结果显示,豆梨显著高于山梨和杜梨,山梨与杜梨间无显著差异。因此,不同生境下的梨属植物木质部导管分子形态及分布与其生态适应性之间有较强的相关性,表现为南方温暖潮湿环境起源的梨砧木导管较短,直径较宽,直接影响木质部导水率,从而适于水分高效输导;北方寒冷干旱环境起源的梨砧木导管较长,直径较小,导水能力低,但木质部导管分布密度高,利于水分安全输导。

Comparison of the Characters and Distribution of Vessel Elements in Xylem Among Three Main Pear Rootstocks in China

The characteristics and distribution of vessel elements in xylem of three main pear rootstocks (Pyrus ussuriensis, P. betuleafolia, P. calleryana) in China were examined by tissue isolation, paraffin sectioning and biometric statistics. The pattern of secondary wall thickening and lignification, pitting pattern, main types of perforation plates and proportion of tail, end walls, and tail length of vessel elements did not differ among the species. However, the proportion of vessel elements with multiperforate perforation and two tapered end walls and vessel frequency were higher in P. ussuriensis and in P. betuleafolia than P. calleryana. The diameter of vessel elements and specific conductivity were higher in P. calleryana than in P. ussuriensis and P. betuleafolia. Morphological structure and ecological adaptability are correlated in Pyrus varieties in different habitats. The vessel elements of pear rootstock species from south China are shorter in length and broader in diameter, which appears to directly affect hydraulic conductance capacity and therefore may be suitable for conducting water with high efficiency. The vessel elements of pear rootstock species from north China are longer in length and smaller in diameter with higher vessel frequency, which may help for conducting water safely.