Enhancement of nitrate uptake and growth of barley seedlings by calcium under saline conditions.
The effect of Ca2+ on NO3- assimilation in young barley (Hordeum vulgare L. var CM 72) seedlings in the presence and absence of NaCl was studied.  Calcium increased the activity of the NO3- transporter under saline conditions, but had little effect under nonsaline conditions.  Calcium decreased the induction period for the NO3- transporter under both saline and nonsaline conditions but had little effect on its apparent Km for NO3- both in the presence and absence of NaCl.  The enhancement of NO3- transport by Ca2+ under saline conditions was dependent on the presence of Ca2+ in the uptake solution along with the salt, since Ca2+ had no effect when supplied before or after salinity stress.  Although Mn2+ and Mg2+ enhanced NO3- uptake under saline conditions, neither was as effective as Ca2+.  In longer studies, increasing the Ca2+ concentration in saline nutrient solutions resulted in increases in NO3- assimilation and seedling growth.
Ward
M R
MR
Department of Agronomy & Range Science, University of California, Davis 95616, USA.
Aslam
M
M
Huffaker
R C
RC
D001692:Biological Transport; D002118:Calcium / Q000494:pharmacology*; D002412:Cations; D005308:Fertilizers; D001467:Hordeum / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D018527:Hydroponics; D008274:Magnesium / Q000494:pharmacology; D008345:Manganese / Q000494:pharmacology; D009566:Nitrates / Q000493:pharmacokinetics*; D012965:Sodium Chloride / Q000494:pharmacology*
D002412:Cations; D005308:Fertilizers; D009566:Nitrates; D008345:Manganese; D012965:Sodium Chloride; D008274:Magnesium; D002118:Calcium