Exogenous Gibberellic Acid or Dilute Bee Honey Boosts Drought Stress Tolerance in Vicia faba by Rebalancing Osmoprotectants, Antioxidants, Nutrients, and Phytohormones

Abstract

The use of growth regulators such as gibberellic acid (GA3) and biostimulants, including diluted bee honey (Db-H) can improve drought tolerance in many crops, including the faba bean (Vicia faba L.). Db-H contains high values of osmoprotectants, mineral nutrients, vitamins, and many antioxidants making it an effective growth regulator against environmental stress effects. Therefore, the present study was planned to investigate the potential improvement in the faba bean plant performance (growth and productivity) under full watering (100% of crop evapotranspiration (ETc)) and drought stress (60% of ETc) by foliar application of GA3 (20 mg L−1) or Db-H (20 g L−1). The ameliorative impacts of these growth regulators on growth, productivity, physio-biochemical attributes, nutrient status, antioxidant defense system, and phytohormones were evaluated. GA3 or Db-H attenuated the negative influences of drought stress on cell membrane stability, ion leakage, relative water content, nutrient status, leaf pigments related to photosynthesis (chlorophylls and carotenoids), and efficiency of the photosystem II (PSII in terms of Fv/Fm and performance index), thus improving faba bean growth, green pod yield, and water use efficiency. Drought stress caused an abnormal state of nutrients and photosynthetic machinery due to increased indicators of oxidative stress (malondialdehyde (MDA), hydrogen peroxide (H2O2) and superoxide (O2•−)), associated with increased osmoprotectants (proline, glycine betaine, soluble sugars, and soluble protein), non-enzymatic antioxidants (ascorbic acid, glutathione, and α-tocopherol), and enzymatic antioxidant activities (superoxide dismutase, catalase, glutathione reductase, and ascorbate peroxidase). However, foliar-applied GA3 or Db-H mediated further increases in osmoprotectants, antioxidant capacity, GA3, indole-3-acetic acid, and cytokinins, along with decreased levels of MDA and abscisic acid. These results suggest the use of GA3 or Db-H at the tested concentrations to mitigate drought-induced damage in bean plants to obtain satisfactory growth and productivity under a water deficit of up to 40%.

Foliar Nourishment with Nano-Selenium Dioxide Promotes Physiology, Biochemistry, Antioxidant Defenses, and Salt Tolerance in Phaseolus vulgaris

“…However, under severe stress, the natural tolerance of plants does not help with stress resistance since the active ingredients of the plant with low-molecular mass and high-molecular mass do not provide sufficient requirements for defense against stress. Therefore, exogenous adjuvants, including beneficial nutrients in nanoparticles and other auxiliary strategies, must be used to raise the efficiency of antioxidant defense in stressed plants to enable them to function effectively under different stresses [7,10,[54][55][56][57][58][59], including salinity [6,[60][61][62].…”

Revitalizing Fertility of Nutrient-Deficient Virgin Sandy Soil Using Leguminous Biocompost Boosts Phaseolus vulgaris Performance

“…Furthermore, the accumulation of ascorbate and glutathione with the S CF75 + F CF25 + C L B treatment contributed to the improved tissue water status and membrane integrity by reducing the activity of the reactive oxygen species (ROS) [ 47 , 92 , 93 ]. It has been explained that the accumulation of K + , free proline, and soluble sugars as osmolytes contributes to osmotic adjustment, which helps to maintain the cell turgor and stabilize the membranes by activation of antioxidant plant defense system [ 73 , 94 , 95 , 96 , 97 , 98 , 99 ]. This is also evident from improvement in antioxidant enzymes activities in this study ( Figure 7 , Figure 8 , Figure 9 , Figure 10 , Figure 11 and Figure 12 ), such as superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (GPOD), including leaf content of protein for the S CF75 + F CF25 + C L B treatment in P. vulgaris plants grown under the tested conditions.…”

Early Sowing Combined with Adequate Potassium and Sulfur Fertilization: Promoting Beta vulgaris (L.) Yield, Yield Quality, and K- and S-Use Efficiency in a Dry Saline Environment

“…These negative impacts may exceed the natural tolerance capacity of stressed plants. In this case, the components of the stressed plant's defense system do not meet the requirements of adequate defense, and therefore the external use of auxiliary substances such as nutrients and other beneficial strategies helps the plants to increase the efficiency of their antioxidant defenses; thus, plants can perform efficiently under adverse conditions of environmental foes [3,4,8,[56][57][58][59].…”