Activated Yeast Extract Enhances Growth, Anatomical Structure, and Productivity of Lupinus termis L. Plants under Actual Salinity Conditions

Salinity is one of the most severe environmental stresses that negatively limits anatomical structure, growth and the physiological and productivity traits of field crops. The productivity of lupine plants is severely restricted by abiotic stress, particularly, salinity in arid and semiarid regions. Activated yeast extract (AYE) can perform a vital role in the tolerance of environmental stress, as it contains phytohormones and amino acids. Thus, field experiments were conducted to explore the potential function of active yeast extract (0, 50, 75, and 100 mL AYE L−1) in mitigating the harmful impacts of salinity stress (EC = 7.65 dS m−1) on anatomical structure, growth, and the physiological and productivity traits of two lupine cultivars: Giza 1 and Giza 2. The different AYE treatments resulted in a substantial improvement in studied attributes, for example the growth, anatomical, physiological characteristics, and seed yields of treated lupine cultivars compared with untreated plants. Among the AYE doses, 75 mL L−1 significantly improved plant growth, leaf photosynthetic pigments, total soluble sugars, total protein, and seed yields, and exposed the best anatomical attributes of the two lupine cultivars grown under saline stress. The exogenous application of 75 mL AYE L−1 was the most influential, and it surpassed the control results by 45.9% for 100-seed weight and 26.9% for seed yield per hectare. On the other hand, at a concentration of 75 mL L−1 AYE there was a decrease in the alkaloids and endogenous proline under the studied salinity stress conditions. Promoted salinity stress tolerance through sufficient AYE dose is a hopeful strategy to enhance the tolerance and improve productivity of lupine into salinity stress. Furthermore, the response of lupine to salinity stress appears to rely on AYE dose. The results proved that Giza 2 was more responsive to AYE than Giza 1, showing a better growth and higher yield, and reflecting further salinity tolerance than the Giza 1 cultivar.