Studies on the Impact of Bio-Fertilizer and Growth Regulators on the Physiological Aspects of Lettuce (Lactuca sativa L.) Plant Under Salt Stress Conditions

Abstract

This study aimed to explain the role of plant growth regulators-PGRs (ascorbic acid - AsA & salicylic acid - SA) in the presence or absence of bio-fertilizer (Acadian extract –ACE) for alleviated the effect of salinity stress on two cultivars of lettuce (cv. Paris & cv. Royal). The lettuce seeds for both cultivars were soaked in PGRs (AsA & SA –0.5 mM) for 12 hours which led to an increase in the percentage of germination. Then the seedlings were irrigated using NaCl salinity concentrations (0.00, 50; 100; 150 mM) 1st group alternative with H2O and 2nd group alternating with ACE (1%). The data explained that the growth parameters, water relations, photosynthetic pigments, enzyme activities, organic and inorganic components increased more in cv. Royal than in cv. Paris, particularly with AsA (-ACE) compared with control. Relative water content and succulents increased significantly, also observed the dry matter content decreased with increasing salinity concentrations especially with AsA (-ACE). Likewise, the evidence recorded increased carbohydrates, protein, proline, and the catalase enzyme for both cultivars under salinity stress with AsA (-ACE) for both growth stages. While polysaccharides recorded the lowest amount for both cultivars at 150 mM of NaCl with all treatments compared to control. Also, the ascorbate peroxidase, glutathione reductase, and superoxide dismutase enzyme activities and the contents of N, P, K, Ca, Mn, Fe, and B mineral elements increased with salinity concentrations especial with 50 mM NaCl concentration in the presence of AsA (-ACE) compared with control. Whereas, the Mg, Na, Cl, Cu, and Zn contents tended to increase with increasing salinity concentrations especially with AsA (-ACE) in both cultivars. Generally, the results showed the success of using PGRs & ACE, and the interfering factors between them in raising the efficiency of plant tolerance to salt stress, particularly with AsA (-ACE) was the best treatments used to reduce the harmful effects of salinity.