Growth Parameters and Bark Structure Characteristics of Hevea brasiliensis Wedge-grafted Seedlings with DifferentCombinations of Root Stock and Scion

PurposeTo explore the growth characteristics and tissue connection mode between the root stock and scion of Hevea brasiliensis (HB) wedge-grafted seedlings, providing a theoretical basis for the relationship between root stock and scion of HB seedlings.

MethodsGT1 seed seedlings and RY73397 anther tissue cultured seedlings were used as root stocks or scions for wedge-grafted of different root stock and scion combinations. The growth parameters of wedge-grafted seedlings and the bark structure characteristics between root stocks and scions were observed, to analyze the growth differences of HB wedge-grafted seedlings with different root stock and scion combinations.

ResultsThe survival rate of self grafting (ZH₁ and ZH₄) was higher than that of other grafting (ZH₂ and ZH₃). The growth parameters (plant height, leaf-whorl number of wedge-grafted seedlings, and stem diameter of root stock and scion) in seedlings without wedge-grafted (control groups: CK₁ and CK₂) were higher than that in wedge-grafted combination seedlings (ZH₁-ZH₄), and there was extremely significant correlated with each other. The thickness of bark, cork layer, phloem and effective phloem, and the number of secondary laticifer rows at the root stock, scion and junction of root stock and scion showed significant differences between the control groups and wedge-grafted groups. There was significant correlation between stem diameter and bark thickness of root stock, stem diameter and number of secondary laticifer rows of the junction of root stock and scion, stem diameter and phloem thickness of scion, while there was no significant correlation between stem diameter and bark structure parameters of other parts.

ConclusionWedge grafting seriously hinders the growth of plant height, leaf-whorl number of wedge-grafted seedlings and the stem diameter of root stock and scion, significantly reduces the number of secondary laticiferous rows of scion bark, and causes swelling or shrinking depression at the junction of root stock and scion, resulting in the mechanical damage of wedge-grafting or the influence of compatibility between root stock and scion varieties. The root stock has a significant induction effect on the laticifer of scion.