J. Gorham et J. Bridges, EFFECTS OF CALCIUM ON GROWTH AND LEAF ION CONCENTRATIONS OF GOSSYPIUM-HIRSUTUM GROWN IN SALINE HYDROPONIC CULTURE, Plant and soil, 176(2), 1995, pp. 219-227
The optimum Ca2+ concentration for growth of cotton (Gossypium hirsutu
m cv. Acala SJ-2) was in the range 1 to 15 mol m(-3) for plants growin
g in hydroponic culture with 100-150 mol m(-3) NaCl. Most saline (but
not sodic) soils contain higher Ca2+ concentrations. CaCl2 was inhibit
ory to the growth of cotton above 20-50 mol m(-3). Increasing concentr
ations of Ca2+ in the range 0-2 mol m(-2) drastically reduced Na+ accu
mulation in the leaves. As CaCl2 concentrations were increased above t
he optimum for growth there was a further reduction in leaf Na+ accumu
lation, but this was more than offset by increased leaf Ca2+ and Cl- c
oncentrations. Leaf K+ concentrations were not much affected by change
s in external CaCl2 concentrations. The response of Mg2+ varied from a
n increase to a decrease with increasing external CaCl2 and was influe
nced by nutritional status. There was no evidence that high Ca2+ cause
d a deficiency of Mg2+ in cotton. Except for Cl-, whose concentrations
tended to decrease initially and then increase as the CaCl2 concentra
tion increased, the anions were largely unaffected by changes in exter
nal CaCl2.