Morphophysiological Responses of Two Chenopodium quinoa Genotypes to Salinity in a Hydroponic System

Abstract

The Chenopodium quinoa is poised to be a promising species for future food security and combating climate change because of its nutritional content and its halophytic peculiarity. This study focuses on the differential responses of salt-tolerant (Chadmo) and salt-sensitive (Kankolla) under control (CK) and 400 mM sodium chloride (NaCl) in five temporal dimensions (1/2, 1, 3, 6, and 24 h post-treatment time points). Morphological and physiological features assessed include root/shoot dry weight ratio, relative water content (RWC), membrane stability index (MSI), total chlorophyll (CHL), and adaxial and abaxial epidermal bladder cells (EBC). The results indicated a reduction in dry biomass for both genotypes after treatment with Chadmo and Kankolla at 46.96% and 73.07%, respectively. Similarly, a significant reduction in the RWC with Chadmo at 16.69 % and Kankolla at 13.19% was detected. Under 400 mM NaCl condition and CK, Chadmo's average net photosynthetic rate reduced from 15.73±2.97 to 13.02±2.75 µmol CO2 m-1s-1, indicating 17.24% reduction while in the Kankolla, the reduction from was 13.43±4.12 to 8.34±3.16 µmol CO2 m-1s-1 representing 37.92% decline. In addition, this study showed a significant difference (p<0.05) being identified on ANOVA and Tukey analyses in root/shoot dry weight ratio, RWC, membrane stability index (MSI), total chlorophyll (CHL), and adaxial and abaxial epidermal bladder cells (EBC). Those measurement criteria increased by 14.45% and 3.45% in Chadmo and Kankolla, respectively, from the CK to 400 mM NaCl. Using these morpho-physiological responses to salinity, Chadmo proved to be the better-performing genotype when exposed to 400 mM NaCl and hence identified as the salt-tolerant genotype.