Effect of salt stress (NaCl) on whole plant CO2-gas exchange in mango.
Schmutz U.
Author Affiliation: Humboldt University Berlin, Section Fruit Science, D-14195 Berlin, Albrecht-Thaer-Weg 3, Germany.
: 269-276
Abstract : In four experiments, the salt tolerance of M. indica cultivars 13-1 and Turpentine and M. zeylanica was characterized in a controlled environment. As salinity increased from 15 to 120 mM NaCl whole plant CO2 gas exchange (CO2 assimilation A, dark respiration RD, root respiration RR and carbon gain CG) was monitored for up to 1 month. At the end of the experiments mineral composition was recorded in various plant parts. Three representative days with 24 measurements for every hour in the day were selected in each experiment, showing that low NaCl concentrations (15 and 30 mM) reduced A and RD 6 days after the treatments started. After 3 more days and an increase to 60 mM NaCl a significant reduction of A was measured compared to control plants. In another experiment, NaCl reduced A in both M. indica cultivars without any clear difference, but 13-1 had lower DR than Turpentine and higher CG. No significant differences in mineral contents were measured, but 13-1 had higher Na+, Cl- and Ca2+ contents in leaves. At 60 mM NaCl A was 8 µmol CO2 m-2s-1 in M. zeylanica and only 3 µmol CO2 m-2s-1 in 13-1. In M. zeylanica a higher value of RR was measured. Significantly lower Na+ contents were found in roots and young leaves of M. zeylanica as compared to 13-1. The K+ contents and K:Na ratio were significantly higher in roots of M. zeylanica. Data indicated only small differences in salt tolerance between M. indica cultivars 13-1 and Turpentine. Promising higher tolerance may exist in M. zeylanica.