The effect of soil strength on germination and emergence of wheat (Triticum aestivum L.). I. Low shear strength conditions

Experimental studies of the germination and emergence of wheat as affected by soil shear strength are reported. A fine sand under saturated conditions was used as the seed bed and the shear strength of the seed bed was increased to 10 kPa (0.1 bar) by externally applied loads. From the results it is concluded that the initial soil shear strength in this range has little effect on germination. However, coleoptile growth and root elongation are markedly reduced in the range 0-2.2 kPa such that total emergence is reduced to 7% at 9.3 kPa in this fine sand. The results clearly show that coleoptile elongation is more affected than root elongation by the same mechanical stress. Roots are found to be thicker and coleoptile thinner under increasing soil shear strength conditions.