Anatomical changes in rubber tree cuttings (Hevea brasiliensis clone RRIM 600) in response to different rooting techniques

Abstract

Clones of Hevea spp are presently grafted on seedlings, because no economic method of producing clonal rootstocks by vegetative means or clonal cuttings has so far been discovered. Because of this, Hevea clones do not exteriorize their maximum genetic potential for latex production. The rooting of clonal cuttings overcomes this problem. However, Hevea is considered a plant with very poor capacity of rooting, in its mature phase. Plants have at the stem base an almost continuous cylinder of lignified tissues, which along with chemical barriers can difficult rooting. At present, rooting problems in some plant species may be overcome by a combination of new techniques as it is the case of total or local etiolation and girdling. This work has the aim to characterize the modifications occurred in clonal cuttings of Hevea when subjected to the above mentioned techniques, alone or combined. It was possible to conclude that the girdling of the cutting base from the RRIM 600 clone, as well as its utilization in combination with the other two types of etiolation, promoted drastic alterations in the sheath, as compared to the control. Moreover, girdling promoted the activity of the vascular cambio, which produced a greater number of parenquimatous cells in the phloem, resulting in a discontinuity, of the perivascular fibers sheath. Other alterations elapsed of the girdling were: the division of parenquimatous cells around of the sheath forming meristematic rings and a greater number of lenticells in comparison to the control, which can favor the rooting of the cuttings.