FINDING HORMONAL HARMONY
While auxins, cytokinins, and gibberellins all occur naturally in a complementary balance within plants, the manipulation of this equilibrium at critical growth stages can build a plant that better tolerates hot, cold, wet, or dry conditions.
For example, applying an auxin product early produces a seedling with more roots, a thicker stem, and more leaf area, providing the plant with a stronger foundation to withstand future stress. However, cytokinin is needed help translocate auxin from the application point to the roots where it is most functional. An auxin/cytokinin mixture in an auxin-dominant ratio is better than relying on the crop’s natural cytokinin production to compensate.
Application of a cytokinin-dominant material near the end of vegetative growth can ensure that seed-producing structures are formed and remain intact to produce grain. The management considerations at this time should include:
- Is there enough moisture and nutrients to support more crop load?
- Are there adequate roots to extract the water and nutrients needed to realize the increased yield potential?
- Does the crop have the leaf structure and photosynthetic capability to maximize grain fill?
All these variables are why an early application of an auxin-dominant product, such as CH Biotech’s Megagro™, is always the best first step. The beauty of early root development is that roots are the primary site of cytokinin production, so the more roots you have, the more branches and fruiting structures will develop naturally. By self-regulation, the plant will never initiate more grain fill than it has the roots to handle.
The addition of gibberellic acid to an auxin/cytokinin mixture can benefit early seedling development. The challenge in this is the degree to which the gibberellic acid is emphasized at any stage of growth. Depending on conditions, an abundance of gibberellins can induce cell enlargement without cell division. This can create tall plants with maximum vegetative growth, but with less stem thickness to support grain load. Gibberellins also mitigate a high degree of stress; but if high stress does not persist, the excess vegetative growth can again become a drain on grain yield. At this point, managing gibberellic applications becomes more art than science, creating both opportunity and risk.