Physio-Biochemical Responses of Soybean to Different Concentrations of Salt Stress and the Protective Role of Biopriming with Trichoderma harzianum

In the present study, the effect of different concentrations of NaCl (0, 25, 50, and 100 mM) on the growth and physio-biochemical responses of soybean (Glycine max L.) and the protective role of Trichoderma harzianum were investigated. In order to investigate the effect of antagonistic fungi pretreatment on saline damage reduction, a factorial experiment in a completely randomized design with four replications was conducted. Changes in chlorophyll a and b, proline, soluble sugars, hydrogen peroxide, and malondialdehyde contents were measured by chlorometric analyses. The results showed that an increase in NaCl concentration in the nutrient solution reduced the height, shoot and root dry weight, and Chlorophyll a and b content in soybean plants while the amount of proline, soluble sugars, hydrogen peroxide and malondialdehyde increased. T. harzianum improved plant growth and photosynthetic pigments 19.58% and 16.10% under saline and non-saline conditions, respectively. A reduction in the accumulation of proline, soluble sugars, hydrogen peroxide, and malondialdehyde was also recorded as T. harzianum was added to soybean seedlings under different concentrations of salt stress. Generally speaking, T. harzianum proved to be very beneficial in increasing the resistance of soybean plants against NaCl stress. Hence, using this bacterium as a new biotechnological approach is suggested for the inoculation of seeds for cultivation in saline lands.