Elimination of Chemical dormancy controls by Leaching

 

There are many species of woody plants in which dormancy is engendered by the presence of a growth inhibitor, such as abscisic acid, in the fruit and/or the pericarp surrounding the seed. With maturity of the fruit this can then permeate the seed - effectively creating a distortion in the initial phases of the chilling process. Fortunately this chemical is freely soluble in water and can be removed fairly efficiently by leaching.

 

Leaching can be achieved by soaking the seeds and then washing or by flushing them in warm water for several iterations. This chemical is often an unexpected and unrecognised presence, albeit in small quantities, but nevertheless needs to be recognised and removed as a matter of course. It will delay the chilling process until it is eliminated – thus distorting the period needed for the chilling procedure.

 

This sort of inhibition probably accounts for the very variable time scales, which appear in the literature, for the chilling requirement of the seeds of such divergent species as apple, many Roses and Mahonia aquifolium.

 

There are many woody plants of arid environments in which the seeds contain a chemical which effectively acts as a rain gauge. Precipitation, in a location with limited rainfall, is often not sufficient for the completion of germination and seedling establishment. The plant has therefore evolved for the seed to contain a particular amount of chemical that is not completely leached until there is a sufficient reservoir in the soil to support the full process. Leaching will normally be effective for these subjects.