The Ion Response and the Mode of Salinity Resistance of Manilkara zapota(L.)van Royen under NaCl Stress
In order to learn the ion response and mode of salinity resistance of Manilkara zapota,the contents and distribution of 4 kinds of ions(Cl-,Na+,K+,Ca2+)in roots,branches,leaves under NaCl stress were measured.The results showed that Cl-,Na+,Ca2+ contents in M.zapota roots,branches,leaves were increased with the NaCl concentration increased,while K+ content and the ratio of K+/Na+ dropped.The Cl-content in roots,branches,leaves was 8.94 times,6.77 times,4.49 times,respectively higher than it in the control under 8‰ NaCl and Na+ content was 2.16 times,2.88 times,2.45 times,respectively.The K+/Na+ ratio in roots,branches,leaves was 0.13,0.43,0.35,respectively.The content of Cl-or Na+ was larger in roots than in branches or leaves under the same NaCl concentration.The Cl-content followed the order: branches leaves roots,Na+content did: leaves branches roots.K+ content did: roots leaves branch,and Ca2+ content did: roots branches leaves.The results showed that most Cl-,Na+ kept in roots after entering the plants.It was deduced that the mode of salinity resistance was salt avoidance for M.zapota and that the imbalance of Ca2+ related to the salt damage.