Researches and practices associated with grafting indicate that the diversity of root-shoot interaction is universal in different physiological processes of plant. Our previous grafting study with CCRI41, an early senescence cotton cultivar, and SCRC22, a late senescence cultivar as materials found that shoot played a major role in mediating leaf senescence of cotton. In the present study, CCRI41 and another late senescence cotton cultivar CCRI49 were used to do standard grafting (I-grafting, one scion grafted onto one rootstock) and Y-grafting (two scions grafted onto one rootstock). Leaf senescence of grafts was induced by low potassium (K; 0.03 mmol L–1). Contrary to the grafting combination of CCRI41 and SCRC22, the combination of CCRI41 and CCRI49 showed that the role of root was more important than that of shoot for leaf senescence, as characterized by SPAD reading. Accordingly, the concentration of ZR+Z or iPA+iP in roots and the youngest fully expanded leaf and their delivery rate in xylem sap regarding I-grafting combinations with CCRI41 as rootstock were significantly lower than those with CCRI49 as root-stock in most of situations. However, the results of free ABA level were exactly opposite. With respect to the Y-grafting of CCRI41 and CCRI49, the results were similar to those of I-grafting, whereas the role of root was not absolutely predominant any more. The mechanism for different root-shoot interactions in cotton leaf senescence was discussed from the perspective of root-shoot-root distance communication.%嫁接研究和实践表明，植物不同生理过程普遍存在根-冠互作的多样性。作者曾以衰老较快的棉花品种中棉所41和衰老较慢的品种鲁棉研22为材料进行嫁接研究，发现地上部对叶片衰老起主要作用。本文以中棉所41和另一个衰老较慢的品种中棉所49为材料进行普通嫁接(I 型，单接穗单砧木)和 Y 型嫁接(双接穗单砧木)，用低钾胁迫(0.03 mmol L–1)诱导叶片衰老，结果表明I型嫁接中以中棉所41为砧木的处理，其倒四叶SPAD值显著低于以中棉所49为砧木的处理，提示根系对叶片衰老的作用较大。相应地，以中41为砧木的处理，其根系和叶片中的 ZR+Z 和iPA+iP 浓度及砧木和接穗木质部汁液中的 ZR+Z 和 iPA+iP 流量在绝大多数情况下显著低于以中49为砧木的处理， ABA的结果则相反。Y型嫁接的结果与I型嫁接相似，但根系对叶片衰老的作用未表现出绝对优势。从根-冠-根通讯的角度对叶片衰老的根-冠互作类型多样性进行了讨论。
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