Relationship between growth and ion relation in pearl millet (Pennisetum glaucum (L.) R. Br.) at different growth stages under salt stress

Abstract

Seedlings of two pearl millet (Pennisetum glaucum (L.) R. Br.) lines were exposed to 0 (control) and 100 mol m–3 NaCl salinity. Treatments were applied fourteen days after germination. Growth of the shoot and root system and ion contents were determined at seedlings (21 days after treatment) and vegetative stage (42 days after treatment). NaCl concentration caused reduction in the plant growth, particularly of the shoot, always with much intensity in the sensitive line. Results obtained indicated that the difference in growth between these two lines might be due to differences in ion transfer rates to the shoot and salt accumulation in the shoot. The sensitive line showed higher Na+ plus Cl- transfer rates to the shoot, especially in the beginning of the stress application and greater accumulation of these ions in the leaves The tolerant line, on the other hand, showed higher K+transfer rates and lower relative reduction in the Ca2+ transfer rates to the shoot under salt stress. So, these results suggest that tolerance to salt stress, in pearl millet lines studied may be related to plant ability to prevent accumulation of toxic ions like Na+ and Cl- and to maintain the shoot. Plant ability to make adequate osmotic adjustment, however, should not be ignored. Keywords: salinity, growth, ions, pearl millet.