Salinity effects on different varieties of Amarantus sp

Abstract

Amarantus sp. is recognized as a promising plant species due to high nutrition value and resistance to adverse environmental conditions. Due to C4 photosynthetic pathway, amaranth can be grown under elevated salinity or water deficit. As salinity is one of the most serious and continuously increasing limiting agents in agriculture, investigations of resistant, high productivity and nutritional value agricultural crops is of particular importance. The aim of this study was to investigate and to compare the resistance of 3 Lithuanian genotypes of Amaranth (‘Raudonukai’, ‘Rausvukai’ and ‘Geltonukai’) to increased salinity. Pot experiments were conducted in growth chambers, plants were exposed to 50 and 150 mM NaCl levels. Seed germination, shoot growth and photosynthetic rate were investigated. At the earliest growth stage ‘Raudonukai’ demonstrated the highest resistance, germinating 2-3 fold better as compared to other varieties. In contrast, growth of aboveground biomass of ‘Raudonukai’ was the most seriously affected (up to 54% decrease), followed by ‘Geltonukai’ and ‘Rausvukai’. Leaf area decreased similarly in all varieties, slightly higher effect was characteristic for ‘Rausvukai’. The photosynthetic rate declined for all plant species with increasing salinity and exposure time. 50mM salinity level had no impact on photosynthetic performance. The strongest effect for ‘Rausvukai’ and ‘Raudonukai’ was observed after 10 days of exposure to 150 mM (up to 33% and 24% inhibition, respectively), followed by adaptation and recovery to control level after 15 days of exposure. Similar reduction of photosynthetic rate was detected for ‘Geltonukai’, however, photosynthetic adaptation was not observed.[...]