ENDOGENOUS PLANT GROWTH REGULATORS AND ROOTING CAPACITY OF DIFFERENT WALNUT TISSUES

摘要

Rooting ability of three different materials, namely cotyledonar linking areas, cotyledonary portions and embryonic microshoots from walnut seeds was determined. It was shown that while cotyledonar linking areas may be defined as a espontaneous rooting system, the other two tissue types correspond to inducible rooting systems, needing exogenous application of auxins for root induction. Endogenous zeatin and isopentenyl type cytokinins, indole-3-acetic acid (IAA), and abscisic acid (ABA) contents were determined in the three kinds of plant material prior to their culture. Our results show that the most active rooting systems has high levels of cytokinins, particularly dihydrozeatin (diH)Z and its riboside, and low levels of IAA and ABA. This situation could indicate that oxidative metabolism was taking place in cotyledonar linking areas, which is generally associated with the initiation phase of the rooting process. So that, we can assume that the induction phase is already overpassed in these tissues. On the contrary, the other two systems in which high levels of auxins and reduced levels of cytokinins were found, need to undergo the induction phase to be able to show root manifestation. In this case, the exogenous auxins are responsible for triggering this process, by enhancement of oxidative conditions. Therefore, it can be conclude that dynamics of growth regulators levels during the different phases of rooting are more important than specific single levels at fixed time. [References: 26]