Effects of Soil Water Deficit on Three Tree Species of the Arid Environment: Variations in Growth, Physiology, and Antioxidant Enzyme Activities

Fahad Rasheed,Waseem Razzaq Khan,Faridah Hanum Ibrahim,Muhammad Abdullah,Adnan Gondal,Zikria Zafar,Muhammad Farrakh Nawaz,Khayyam Anjum,Claire Depardieu,Kamziah Abdul Kudus,Mohd Nazre,Seemab Akram,Shazia Afzal,Ahmad Mustapha Mohamad Pazi

doi:10.3390/su13063336

Abstract

Low water availability predicted under climate change is a major abiotic factor limiting plants growth and productivity. In this study a greenhouse experiment was conducted on three important tree species of arid environment: Conocarpus erectus (CE), Acacia modesta (AM), and Salix tetrasperma (ST). Young saplings were subjected to control (C), medium (MWD) and severe soil water deficit (SWD) treatments and response was evaluated. Results showed that in all the three species leaf, stem and root dry weight production remained similar to C under MWD treatment but decreased significantly under SWD. The highest decrease in total dry weight was noticed in ST and the lowest was evidenced in AM under SWD. Root:shoot ratio increased significantly in both CE and AM under MWD and SWD. Furthermore, chlorophyll content decreased while proline content increased significantly in both MWD and SWD treatments. The production of oxidants (hydrogen peroxide and superoxide anions) and antioxidants (superoxide dismutase, catalase, peroxidase and ascorbate peroxidase) increased significantly under both MWD and SWD treatments and were the highest in AM in both MWD and SWD treatments. Therefore, we may conclude that all the three species can tolerate medium water stress due to increased root production and an effective antioxidant defense mechanism.

Highlights

Climate change induced drought has become a major threat to plant productivity [1]
In soil water deficit (SWD) treatments, the highest decrease in mean plant height, stem diameter and number of leaves was noticed in Salix tetrasperma (ST) (29, 25, and 37%, respectively) and the lowest decrease was noticed in Acacia modesta (AM)
The results showed that all the three species were able to tolerate the medium soil water deficit (MWD) as total dry weight production remained similar to control under this treatment

Summary

Introduction

Climate change induced drought has become a major threat to plant productivity [1]. Changes in biochemical mechanisms are a major part of the plant response to various environmental stresses [14] Such a response includes increased production of reactive oxygen species (ROS) in the form of superoxide anions (O2− ), singlet oxygen (1 O2 ), hydroxyl radicals (OH), hydrogen peroxide (H2 O2 ), and alkoxy radicals (RO). Overproduction of these oxidants damages the cell membrane, proteins, lipids and nucleic acids and sometime may lead to cell death under severe conditions [15,16]. SOD converts O2− into H2 O2 and O2 , and CAT and POD scavenge H2 O2 into

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