Effects of Exogenous Salicylic Acid (SA), 6-Benzylaminopurine (6-BA), or Abscisic Acid (ABA) on the Physiology of Rosa hybrida ‘Carolla’ under High-Temperature Stress

Abstract

The study of the regulatory mechanism of exogenous plant growth regulators (PGRs) on the relevant physiological indicators is essential to maintain the normal growth of Rosa hybrida under high-temperature conditions. The photosynthetic and physiological characteristics of the ornamental cut rose Rosa hybrida ‘Carolla’ under high temperature were studied by spraying leaves with various concentrations of exogenous salicylic acid (SA; 0.5, 1.0, 1.5, or 2.0 mmol·L−1), 6-benzylaminopurine (6-BA; 10, 20, 30, or 50 μmol·L−1), abscisic acid (ABA; 10, 20, 30, or 50 mg·L−1), or distilled water (control). The results indicated that a foliar spray of either SA, 6-BA, or ABA could mitigate the impact of high temperatures. Compared to the control, the application of SA, 6-BA, or ABA increased the net CO2 assimilation rate (An), transpiration rate (E), stomatal conductance (Gs), and water use efficiency (WUE) of ‘Carolla’, while decreasing the leaf relative electrical conductivity (REC) and malondialdehyde (MDA) content. The applications of SA, 6-BA, or ABA increased the activities of the antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX) and altered the proline (Pro), soluble protein, and soluble sugar contents. The results showed that foliar sprays of SA, 6-BA, or ABA could enhance the heat tolerance of ‘Carolla’ by promoting photosynthesis, cell membrane structural stability, antioxidant enzyme activity, and osmoregulation in plants under high-temperature stress. The experiment showed that 1.5 mmol·L−1 SA, 20 μmol·L−1 6-BA, or 20 mg·L−1 ABA could alleviate the damage caused by high temperatures, with 20 μmol·L−1 6-BA having the best effect.

The role of γ-aminobutyric acid and salicylic acid in heat stress tolerance under salinity conditions in Origanum vulgare L.

“…In Rosa hybrida 'Carolla' plant SA promoted photosynthesis, antioxidant enzymes activities and osmoregulation followed by quenching the effects of heat stress. In addition, foliar sprays of SA had protective effect on cell membrane structural stability [44]. The same results were reported in Saponaria officinalis.…”

Exogenous Proline Enhances Systemic Defense against Salt Stress in Celery by Regulating Photosystem, Phenolic Compounds, and Antioxidant System

“…REC was determined as described by Wang et al [ 66 ]. After washing the celery leaves with deionized water, 12 round pieces of celery leaves with a diameter of 0.5 cm were collected from each treatment, evacuated with a vacuum pump for 30 min, surged on a shaking table for 3 h, and equilibrated at room temperature for 2 h. Next, the initial conductivity (S 1 ) was measured using a Ddsj-308f conductivity meter (Shanghai INESA Scientific Instrument Co., Ltd., Shanghai, China).…”

Phytohormones Promote the Growth, Pigment Biosynthesis and Productivity of Green Gram [Vigna radiata (L.) R. Wilczek]

“…For pH estimation, soil mixing with water in a ratio of 1:2.5 was performed in order to prepare the paste, which was thereafter subjected to analysis with a glass electrode [65]. The estimation of electrical conductivity (EC) was performed with the help of a conductivity meter [29][30][31][32][33]. In addition, organic carbon (OC) content assessment was performed by putting the wet oxidation method into practice, and the Walkley-Black protocol was used to determine the organic matter (OM) content [66].…”

“…Exogenously applied SA in a concentration of 1 mM was more effective in increasing plant growth in comparison with higher concentrations, while the underlying mechanism of the growth-restricting impact of higher doses of SA still awaits further research [14,16]. Moreover, foliar-applied SA resulted in significant increments in Ca + and K + content within plants, which improved cell walls permeability for nutrients present in the cell sap [29][30][31][32]. Furthermore, it boosted plant growth and development by reducing the biosynthesis of ethylene and preventing micronutrient toxicity, and through lipid peroxidation, which protected the crop plants from membrane damage [33][34][35][36].…”