Maximizing Faba Bean Tolerance to Soil Salinity Stress Using Gypsum, Compost and Selenium

Saline soil can be difficult to manage, as it lacks the nutrients needed for plant growth, but with the use of agricultural techniques and appropriate fertilization programs, agricultural productivity can be increased from these soils. So, a field trial was implemented to evaluate the possibility of alleviation of oxidative-stress induced by soil salinity stress on faba bean plant via soil addition of gypsum and compost and foliar application of selenium at different rates. Four soil amendment treatments [T0: Without any soil addition (control); T1: Gypsum at rate of 7.2 Mg ha-1; T2: Compost at rate of 7.2 Mg ha-1; T3: Gypsum +compost at rate of 3.6 Mg ha-1 for each of them] represented the main plots. While five selenium rates [Se0: Without selenium (control); Se1: With selenium (2.5 Se mgL-1); Se2: With selenium (5.0 Se mgL-1); Se3: With selenium (7.5 Se mgL-1); Se4: With selenium (10.0 Se mgL-1)] were allocated in the sub plots. The maximum values of both MDA and proline (9.51 and 9.61 for MDA and 6.64 and 6.71 for proline in both studied seasons, respectively) were achieved under control treatment. While the lowest one (4.99 and 5.05 for MDA and 3.84 and 3.89 for proline in the 1st and 2nd seasons, respectively) were realized under the combined treatment (gypsum+ compost). Concerning the selenium treatments, the maximum values of both MDA and proline (7.61 and 7.7 for MDA and 5.71 and 5.79 for proline in both studied seasons, respectively) were achieved with plants sprayed with 10.0 Se mg L-1 followed by the control treatment (grown without Se), while the lowest one (6.35 and6.44 for MDA and 4.95 and 5.01 for proline in both seasons, respectively) were realized with plants sprayed with 5.0 Se mg L-1. On the other hand, the combined treatment of gypsum and compost was the most effective in achieving the highest values for all traits of growth performance and productivity, followed by the treatment of compost alone then gypsum alone which was less effective and lately the control treatment. The selenium treatments had a significant and gradual impact on all the traits of growth performance and productivity, with an increase observed as the Se rate was increased from 0.0 mgL-1 to 5.0 mgL-1, followed by a significant and gradual decrease until the selenium concentration reached 10.0 mgL-1. Notably, the values obtained under the control treatment were superior to those observed under the Se4 treatment (10.0 mgL-1), indicating that excessive selenium application may have a negative effect on the traits. Generally, the combination of T3 and Se2 treatments resulted in the most favorable growth performance and productivity for faba bean cultivation under saline soil conditions.
Finally, it is recommended that farmers dealing with salt-affected soil use a combination of gypsum and compost to improve soil quality and plant growth. Additionally, when adding selenium to the plant, it is crucial to consider the dose and avoid excessive application, as this may have a negative impact on plant growth, especially under salt-affected conditions.