Effect of salinity stress on growth and nutrient uptake in polyembryonic mango rootstocks

Abstract

Six-month-old, uniform-sized seedlings of seven mango (Mangifera indica L.) rootstocks namely Moovandan, Bappakai, Nekkare, Kurukkan, Olour, Terpentine and Chandrakaran were irrigated to 70% of field capacity with water containing 0, 50, 100, and 150 mM NaCl for 90 days. Growth in terms of plant height, number of leaves and leaf area per plant decreased with increasing levels of salinity in all rootstocks. The decrease in growth was greatest in the salt-susceptible Chandrakaran rootstock (32.02%) at higher levels of salinity. However, in the salt-tolerant Olour and Nekkare, NaCl caused only a slight decrease in numbers of leaves and leaf area per plant. A declining trend was observed in fresh and dry weight of plant with increasing concentration of NaCl in all rootstocks and maximum decrease was found in Chandrakaran (73.43% in shoot and 57.20% in root) whereas minimum was in Olour. The concentration of Na+ ions in leaf tissues increased to a maximum (123.53%) in Chandrakaran and in root tissues Bappakai had the highest Na+ ions (77.27%) content. The maximum increase (109.09%) in leaf Cl- ions level occurred in Moovandan and Chandrakaran had the highest (139.29%) root Clions content at 150 mM NaCl. These data suggest that lower levels of Cl- and Na+ accumulation could be used as indicators for screening mango rootstocks for resistance to NaCl stress. Olour, Terpentine and Nekkare can exclude Cl- ions; however, Kurukkan, Bappakai, and Moovandan rootstocks seems to be Na+ excluder upto lower level of salt concentrations. Based on overall performance and leaf scorching, it could be said that salinity tolerance increased in the following order Chandrakaran < Moovandan < Bappakai < Nekkare < Kurukkan < Terpentine < Olour.