Morpho-Physio-Biochemical and Molecular Responses of Maize Hybrids to Salinity and Waterlogging during Stress and Recovery Phase.

Umer Mahmood,Mohamed A El-Esawi,Sami Asir Al-Robai,Christophe Hano,Sadam Hussain,Umair Ashraf,Shahid Zamir,Saddam Hussain,Fatima Omari Alzahrani,Basharat Ali

doi:10.3390/plants10071345

Abstract

Maize is one of the most economically important cereal crops worldwide. Salinity coupled with waterlogging is a major challenge for successful crop production. Understanding the underlying mechanisms and impacts of individual and combined salinity and waterlogging stress on the morpho-physio-biochemical and molecular responses and oxidative metabolism of maize during stress and recovery periods is essential. The present study was carried out to assess the response of four hybrid maize cultivars viz. DK-6142, FH-1231, FH-949, and MALKA-2016 under individual and combined salinity and waterlogging conditions. The treatments comprised the control (no stress), NaCl (salinity with 10 dSm−1), WL (waterlogged conditions with 3 cm flooding), and NaCl + WL (combined salinity and waterlogging stress). The data regarding morpho-physiological attributes were collected at 22 days after sowing (DAS; stress phase) and 30 DAS (recovery phase). The results revealed that both stresses, either individually or in combination, substantially reduced the root-shoot length, root-shoot fresh and dry weights, leaf width, and the number of leaves per plant as well as the leaf chlorophyll (Chl) and carotenoids contents; however, the inhibitory effects were more severe in combined stresses than for individual stress factors in many cultivars. Both individual and combined stress conditions enhanced hydrogen peroxide (H2O2) accumulation, whereas the antioxidant enzyme activities, i.e., superoxide dismutase (SOD), peroxidase (POD) catalase (CAT), and ascorbate peroxidase (APX), remained higher under stress conditions compared to the control. The expression levels of antioxidant genes (CAT and POD) were also upregulated under stress conditions. All of the cultivars recovered better from individual stresses than combined stress conditions; however, the hybrid DK-6142 performed better than the other maize hybrids under stress conditions and showed faster recovery.

Highlights

IntroductionSalinity coupled with waterlogging is a major challenge for successful crop production
Salinity coupled with waterlogging is a major challenge for successful crop production.Both of these stresses are major obstacles to the long-term sustainability of irrigated lands, efficient crop production, and farmer subsistence, especially in the Indus Basin area of Pakistan [1]
Irrespective of cultivars, the root length of maize cultivars at 30 days after sowing (DAS) was increased by 87%, 85%, 86%, and 82% under the control, salinity, waterlogging, and combined salinity and waterlogging treatments, Plants 2021, 10, x FOR PEER REVIEWrespectively, compared with those at 22 DAS

Summary

Introduction

Salinity coupled with waterlogging is a major challenge for successful crop production. Both of these stresses are major obstacles to the long-term sustainability of irrigated lands, efficient crop production, and farmer subsistence, especially in the Indus Basin area of Pakistan [1]. Maize is an important cereal crop and consumed as a staple food worldwide [2], whereas salinity and waterlogging are the major constraints to its growth and productivity [3,4]. Under salinity stress, the accumulation of Na+ disrupts the uptake of K+ , which reduces stomatal conductance and creates water-deficit conditions for plants [12]. Salinity results in excessive production of reactive oxygen species (ROS) [14] and a decrease in chlorophyll contents [15]

Objectives

Methods

Results

Discussion

Conclusion