Root biochemical responses of grain and sweet-forage sorghum cultivars under saline conditions at vegetative and reproductive phases

Sorghum is a major oilseed crop, cultivated in arid and semi-arid parts of the world. In order to study the effect of salinity stress on root oxidants, antioxidants, and osmolytes, a factorial experiment based on a completely randomized design with four replications was conducted to study five salinity levels (control, 50, 100, 150, and 200 mM NaCl) and two newly released grain (Kimia) and sweet-forage (Pegah) cultivars of sorghum at two vegetative and reproductive phases. At both phases, salinity stress decreased cell membrane stability accompanied by increasing in all antioxidative enzymes and osmotic compounds. Furthermore, the sweet-forage cultivar tolerated salinity better owing to higher cell membrane stability, lower H2O2, and higher antioxidant enzyme activity. Likewise, salinity tolerance of sorghum was significantly different at vegetative and reproductive phases. Except for lower K+: Na+ ratio, all biochemical compounds were higher at reproductive phase. It assumed that evaluation of biochemical compounds of roots can be useful to study sorghum tolerance to the salinity stress.