Les bruyères in vitro. VI. Croissance de Calluna vulgaris sur milieu strictement nitrique ou ammoniacal et cinétique du pH en fonction du développement des plantes

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Abstract
Calluna vulgaris L. Hull was cultured in vitro on a medium containing either nitrate or ammonium salts. Apical shoots, used as cuttings, regenerated twigs and roots after 15 to 25 days. The uptake of mineral nitrogen by roots had an influence on the pH of the medium. There was either an increase of pH when the N source was NO3 or a decrease in pH of the medium with ammonium. Acidification began with the formation of the first new roots; an increase in pH occurred later with the formation of second order roots. The results were difficult to express, owing to rooting heterogeneity. This problem was overcome by changing the origin of the abscissa, the new origin starting with the date of rooting. This procedure allowed the study of pH changes in relation to different stages of plant growth. With the aid of a standard curve, the study of the leakage of H+ and OH- showed great homogeneity in plant behaviour.