This work was conducted during two successive seasons of 2006 and 2007 to compare the effect of some natural and chemical pre soaking treatments on germination of strongly hard coated carob seed and seedling subsequent growth performance. Natural treatments included : soaking seeds into hot water, soaking scarified seeds into emulsion of essential oils, soaking seeds into emulsion of essential oils in hot water. Whereas, chemical treatments included : soaking seeds into sulfuric acid, formic acid, sulfuric + formic acids, hydrogen peroxide, naphthalene acetic acid (NAA) and scarified seeds into NAA solution. All treatments in comparison with soaking into water at ambient temperature (control) and mechanical scarification the common pre sowing traditional method for hard coat seeds. In all cases, soaking period was 24 hrs.
All treatments were significantly varied in their effect on germination %, germination rate and velocity as well as subsequent seedling growth characters (seedling length, root length, number of leaves and dry weight). All treatments except formic acid were significantly superior than the control, also, most treatments were superior than the traditional scarification in both seasons.
The most effective natural treatments of the highest significant value for germination and growth parameters were soaking scarified seeds into sage oil emulsion, soaking non scarified seeds into emulsion of mint oil in hot water, soaking non scarified seeds into emulsion of sage oil in hot water. These treatments increased the germination % and the seedling dry weight. The germination % were 100 %, 98 % and 95 % respectively and 42.5 % and 0.0 % for the traditional and control ones respectively, the same treatments greatly enhanced the subsequent growth, caused increments of 62.3 %, 48.1 % and 12.7 % (mean of the two seasons) for seedling dry weight respectively relative to the traditional one. Whilst the most superior chemical treatment was soaking the scarified seeds into NAA solution that caused increments of (93.6 % and 44.8 %) for germination % and seedling dry weight respectively with 82 % germination percentage.
Therefore, it is recommended to soak carob seed before sowing for 24 hrs into mint oil (2.5 %), emulsified in hot water of 80 oC initial temperature without scarification as a natural, safe and practical method for the pest germination and subsequent growth performance.