摘 要 ：缺硼可导致柑橘叶片变厚而脆、发生木栓化、"猴头果"等现象,其原因是植物组织内部起运输作用的维管组织受到损坏。导管是维管组织重要组成部分,本实验以‘纽荷尔’脐橙(Citrus sinensis Osbeck ‘Newhall’)和HB柚[Citrus maxima (Burm.) Merr.‘HB You’]叶片、HB柚果实中果皮为材料,利用离析方法将导管分离,观察缺硼导管分子形态的变化。结果表明:(1)缺硼使纽荷尔脐橙叶脉中的孔纹导管数量增多;(2)缺硼使HB柚叶片和果实中果皮的孔纹导管大量增生,梯纹导管和网纹导管数量减少;(3)正常导管圆润饱满,而缺硼导管变形干瘪,且有侧壁穿孔现象;(4)缺硼导管变得短而窄,细胞壁变薄,无尾率增加,使维管组织功能丧失。(5)缺硼维管束受损,运输效率降低,是发生叶脉木栓化和"猴头果"现象的源头。
Abstract:Boron deficiency resulted in thick and brittle leaves, suberification, and "contract fruit" in citrus, due to damaged vascular tissue, which usually functions for transportation. Vessels are an important component of vascular tissue. Morphological abnormalities of the vessel elements were observed using the leaves of ‘Newhall’ (Citrus sinensis Osbeck) Navel orange and HB Pummelo [Citrus maxima (Burm.) Merr.] by separating the vessels by means of segregation. Results indicated that: (1) The number of pitted vessels in ‘Newhall’ Navel oranges with boron deficiency increased; (2) A larger number of pitted vessels in the nervure and mesocarp of HB Pummelo with boron deficiency were proliferated, while scalariform vessels and reticulate vessels decreased; (3) Normal vessels were round and full, while vessels under boron deficiency were transubstantiated shriveled; (4) Compared with the control vessels, vessels under treatment became short and narrow, cell walls turned thin and the percentage of no-tail under boron deficiency condition was increased, which finally led the vascular tissue to lose its function; (5) The headstream of the suberification and "contract fruit" was that the vascular bundles with boron deficiency were damaged and transportation efficiency was decreased.