Effects of silicone nano oxide coated with humic acid and salicylic acid on some morphological parameters and ionic composition of black cumin (Nigella sativa L.) under salinity stress

In order to evaluate the effects of silicone nano oxide coated with humic acid and salicylic acid on some morphological parameters and ionic composition of black cumin (Nigella sativa L.) under salinity stress, two set of experiments were conducted (in lab. and greenhouse) during 2016-2017. First, silicone nano oxide was coated by different concentrations of humic acid (40-1600 mg l-1) in the presence of salicylic acid (pH=4) and at different times (0.5 to 120 hours) to maximize the coverage and energy absorption. Then, the effects of coated silicone nano oxide were evaluated in salinity stress in a split plot experiment based on randomized complete blocks with four replications. The salinity treatment was applied in three levels including 2 ds m-1 as control, 3.5 and 5 ds m-1 with irrigation. The coated silicone nano oxide treatments included 0, 0.25, 0.5 and 0.75 g l-1, applied via irrigation at two growth stages of black cumin (vegetative and reproductive). The results of laboratory experiment showed that by increasing humic acid concentration and exposure time (in presence of salicylic acid), the carbon adsorption rate increased from 6.6 to 11.9 mg g-1. However, the size of silicone nano oxide was not significantly different (20 to 30 nanometers). Results of analysis of variance showed that changes in dry weight of shoot, root, plant height, shoot/root ratio, number of branches, relative water content, and potassium in the salinity treatments and coated nanoparticles were independently significant. It is concluded that the silicone nano oxide coated with humic acid and salicylic acid can result in increased salinity tolerance of the black cumin through reducing the amount and frequency of these materials.