Germination and Development of Heather and the Hydrogen Ion Concentration of the Medium

Abstract

SEVERAL workers^1–3 have shown that, in the field, heather (Calluna vulgaris Salisb.) is found most frequently and attains its maximum development on soils the reactions of which are about pH 4. I have examined the germination and the subsequent seedling development of Calluna seeds planted on agar media adjusted to give a range of reactions. A quantity of 1 per cent British agar was prepared with a form of Knop's solution. This was divided equally between nine flasks. The contents of these were adjusted to pH 2, 3, 4, 5, 6, 7, 8, 9 and 10, respectively, by the addition of the requisite quantities of sulphuric acid or caustic soda. After adjustment, the agar in each flask was poured into six 1-in. boiling tubes to give a depth of agar of about 1½ in. The tubes were plugged and the agar allowed to set. A liberal sowing of Calluna seeds was then made in all tubes.