Calcium uptake and distribution in plants

Abstract

Calcium uptake and distribution in plants are influenced by many factors. Root uptake seems to be independent of metabolic inhibitors but transfer to shoots is drastically reduced by such inhibitors. K uptake increases with root temperature which in turn results in depressed Ca uptake. Plant species differences in the proportion of K vs Ca uptake are often related to root cation exchange capacity. The cations K, Mg, Na, NH4⁺, and H⁺ directly and indirectly depress Ca uptake and distribution. Their effects are more pronounced at low Ca concentrations than at high. Lime‐induced chloros.is is associated with depressed Ca levels in leaves and tests under controlled conditions indicate that bicarbonate results in root retention of Ca and a decrease of Ca in leaves. Nitrate as a complementary ion promotes Ca uptake by plants. Trace metals in excess inhibit calcium uptake. Aluminum in particular greatly depresses Ca retention by roots as well as Ca uptake and transport to shoots. Leaves generally increase in Ca with age. Magnesium can result in phytotoxiciiy when Ca levels are low and this may be involved in crop Ca disorders. Leaf fruit or seed transfers of Ca can be related to concentration of Ca in leaves.

Key words:

• Calcium
• long distance transport
• cation competition
• root cation exchange capacity
• rootstocks
• xylem exudate
• calcium in fruit
• trace metals