Interaction between the Plant Growth Retardant Cycocel and the Plant Growth Stimulant Indol Acetic Acid (IAA)

Abstract

1. Since IAA stimulates the growth and cycocel acts as retardant for the growth of the roots we set out to determine whether is any interaction between CCC and IAA (indol 3-acetic acid) in the effects they produce on mitosis.2. After 4 hours combined treatment of IAA in the previously mentioned concentrations and 12, 000 ppm CCC, there is a depression in the mitotic indices. Cells fixed one hour later after the above mentioned combined treatment show an increase in MI. On the other hand cells fixed 2 hours later showed a decrease in MI. This trend in decrease the MI continues in the following 4 hours.3. Sticky in the highest concentrations, C-anaphases-micronuclei and multinucleated cells are the types of abnormalities which were observed after the combined treatment of IAA with 12, 000 ppm CCC.4. The treatment of Vicia faba root cells with 400 ppm IAA and 12, 000 ppm CCC, causes the formation of tetraploid cells and multipolar anaphases in relatively high frequency.5. The data from roots treated with cycocel indicates that this treatment induce alternation in the duration of mitotic cycles of cells. We have concluded that these alternations occur from changes in the numbers of cells in prophase and metaphase and the numbers of tetraploid metaphases seen in treated roots. On the other hand this change can be counteracted by supply different concentrations of IAA to a relatively moderate concentration of cycocel.6. In addition a partial antagonistic effect was reported after treating Vicia faba roots with 600 and 400 ppm IAA and 12, 000 ppm CCC. This finding agrees with the results of other investigations who concluded that antagonism between any two substances was never total.