美国山核桃嫁接愈合过程的组织细胞学观察

【目的】揭示美国山核桃(Carya illinoinensis)嫁接愈合过程的组织细胞学特征。【方法】以2年生‘马罕'实生苗为砧木,接穗取自‘波尼'品种的1年生枝条,采用切接法进行嫁接,对其嫁接愈合过程进行了组织细胞学观察。【结果】美国山核桃的嫁接愈合过程历经砧穗隔离期(1～9 d)、愈伤组织生长期(9～20 d)、形成层环构成期(20～25 d)和新生维管组织分化期(25～40 d)4个时期。嫁接后1个月左右形成愈伤组织桥和形成层环,为嫁接成活的关键期; 在未成活的嫁接体中,愈伤组织细胞较少并褐化,不能完成愈合过程。【结论】美国山核桃接穗愈伤组织大量发生的时期早于砧木,愈伤组织大量发生期与叶片展开在同一时期; 愈伤组织主要在形成层处产生; 愈伤组织生长受阻,嫁接愈合过程中断可能是影响嫁接成活的重要内因。因此,为愈伤组织的生长与形成层环的构成创造有利条件,是嫁接技术改进、提高嫁接成活率的重要途径。

Histo-cytological observation on the graft union formation in Carya illinoinensis

【Objective】The purpose of this study was to reveal the histo-cytic characteristics of pecan(Carya illinoinensis)during the process of graft union. 【Method】One-year-old scions of the ‘Pawnee' cultivar were grafted on the two-year-old seedlings of ‘Mahan' by cut grafting, and a histo-cytological observation was performed during the process of graft union. 【Result】Four periods in the process of graft union was observed, including the isolation period of scion and rootstock(1-9 d), callus growth period(9-20 d), cambium ring formation period(20-25 d), and new vascular tissue differentiation period(25-40 d). The callus bridge and cambium ring were formed one month after grafting, which was assumed to be the critical period of graft survival. The union cannot be completed in the dead grafts, in which callus cells were less and browning.【Conclusion】Large amounts of callus occurred in scions earlier than that in rootstocks and the leaves unfolded at the stage when the large amounts of callus occurred; the callus mainly formed in cambium; the inhibition of the growth of callus and the interruption of the process of graft union may be the important factor influencing grafting survival. To improve grafting techniques and grafting survival rate, it appears important that the conditions need to be explored to promote the growth of the callus and the formation of cambium ring.