Exogenous putrescine effect on cation concentration in leaf of Brassica juncea seedlings subjected to Cd and Pb along with salinity stress

摘要

The present study reports on cation levels in leaf tissue of the mustard seedlings subjected to metal and salinity stress (Cd/Pb 0.1-2mM and NaCl (50-100mM) for 7 days in controlled conditions. The leaf content of Na~+/K~+ decreased gradually on increase in Pb or Cd level. But under metal and salinity stress, Na~+ level rose considerably with concomitant decline in K~+ level. Exogenously applied putrescine caused considerable decline in Na~+ level, while increased K~+ level in leaf of the seedlings under low salinity and metal (Pb/Cd) stress. The considerable Na~+ accumulation in leaf under high saline and metal stress conditions were reversed up to 35% with putrescine. However, the declining trend in Ca~(++)/Mg~(++) with increasing level of Pb or Cd along with salinity in external environment of the seedlings changed little but significant with putrescine. IAA application to the plant exposed to metal and salinity stress also checked the increase in Na~+ level, but K~+ level change was little. The IAA also had little effect on Ca~(++) / Mg~(++) accumulation over control under severe stress. The experiments suggest the putrescine alleviation of growth in metal and salinity stressed plant through maintaining high K~+ level and lowering Na~+ in leaf, while little effect on divalents (Ca~(++) and Mg~(++)) level. This indicates the possibility of putrescine selective effect on ion flux in leaf es of plants under stress.