Trichoderma-Induced Enhancement of Soybean Seedling Performance in Response to Salt Stress

In this experiment soybean seeds were pre-treated with salt tolerant isolate of Trichoderma harzianum to evaluate the different aspects of seedling growth and metabolism in response to different concentrations of NaCl. Trichoderma isolate was more effective in improving dry weight and root volume of seedlings during mild salt stress. Seedlings obtained from bioprimed seeds had significantly higher leaf greenness, chlorophyll fluorescence, net photosynthesis and stomatal conductance than the control at all stress levels. NaCl-induced membrane damage was alleviated by Trichoderma, especially at 3 dS/m. The biopriming treatment showed lower accumulation of malondialdehyde (MDA) content under saline condition. Highest MDA content was recorded in the control (unprimed) seeds at salinity level of 9 dS/m. A common factor that adversely affects plants under saline conditions is generation of reactive oxygen species (ROS) and we tested the hypothesis that seed biopriming alleviated damages resulting from ROS attack in the stressed plants. Greatest catalase activity was detected in the bioprimed seeds at the salt stress level of 9 dS/m. The activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) were significantly increased in response to NaCl stress. Seed biopriming enhanced SOD and APX activity averaged over all salinity levels. It could be concluded that seed biopriming with Trichoderma harzianum certainly ameliorated harmful impacts of mild salinity mainly through promotion of early seedling development and antioxidative defence system.