Promotion of Growth and Physiological Characteristics in Water-Stressed Triticum aestivum in Relation to Foliar-Application of Salicylic Acid

Abida Parveen,Iqbal Hussain,Al-Bandari Fahad Al-Arjani,Allah Ditta,Muhammad Arslan Ashraf,Elsayed Fathi Abd Allah,Shagufta Perveen,Shahid Hussain,Abeer Hashem,Qaisar Mahmood,Abdulaziz A Alqarawi,Rizwan Rasheed

doi:10.3390/w13091316

Abstract

The present work reports the assessment of the effectiveness of a foliar-spray of salicylic acid (SA) on growth attributes, biochemical characteristics, antioxidant activities and osmolytes accumulation in wheat grown under control (100% field capacity) and water stressed (60% field capacity) conditions. The total available water (TAW), calculated for a rooting depth of 1.65 m was 8.45 inches and readily available water (RAW), considering a depletion factor of 0.55, was 4.65 inches. The water contents corresponding to 100 and 60% field capacity were 5.70 and 1.66 inches, respectively. For this purpose, seeds of two wheat cultivars (Fsd-2008 and S-24) were grown in pots subjected to water stress. Water stress at 60% field capacity markedly reduced the growth attributes, photosynthetic pigments, total soluble proteins (TSP) and total phenolic contents (TPC) compared with control. However, cv. Fsd-2008 was recorded as strongly drought-tolerant and performed better compared to cv. S-24, which was moderately drought tolerant. However, water stress enhanced the contents of malondialdehyde (MDA), hydrogen peroxide (H2O2) and membrane electrolyte leakage (EL) and modulated the activities of antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as accumulation of ascorbic acid (AsA), proline (Pro) and glycine betaine (GB) contents. Foliar-spray with salicylic acid (SA; 0, 3 mM and 6 mM) effectively mitigated the adverse effects of water stress on both cultivars. SA application at 6 mM enhanced the shoot and root length, as well as their fresh and dry weights, and improved photosynthetic pigments. SA foliage application further enhanced the activities of antioxidant enzymes (SOD, POD, and CAT) and nonenzymatic antioxidants such as ascorbic acid and phenolics contents. However, foliar-spray of SA reduced MDA, H2O2 and membrane permeability in both cultivars under stress conditions. The results of the present study suggest that foliar-spray of salicylic acid was effective in increasing the tolerance of wheat plants under drought stress in terms of growth attributes, antioxidant defense mechanisms, accumulation of osmolytes, and by reducing membrane lipid peroxidation.

Highlights

The distribution of plant-life is largely dependent on water in comparison to with other abiotic factors [1]
Drought stress (60% field capacity) was found to significantly (p ≤ 0.001) reduce the shoot length, root length and fresh and dry weights in both wheat cultivars compared with control conditions
Our results indicated that activities of the antioxidant enzymes, SOD, POD and CAT increased when wheat plants were subjected to drought stress conditions

Summary

Introduction

The distribution of plant-life is largely dependent on water in comparison to with other abiotic factors [1]. Water stress induces overproduction of reactive oxygen species (ROS), such as singlet oxygen species (1O2 ), hydrogen peroxide (H2 O2 ), superoxide anions (O2 -) and hydroxyl radical (OH-) which damage membrane lipids, cellular proteins, chlorophyll pigments and nucleic acids [10,11]. Under severe stress, this damage leads to intracellular death and eventually plant death [12].

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