Silicon-Mediated Physiological and Agronomic Responses of Maize to Drought Stress Imposed at the Vegetative and Reproductive Stages

Dongfeng Ning,Jiyang Zhang,Anzhen Qin,Aiwang Duan,Zugui Liu,Ben Zhao,Junfu Xiao,Zhanjun Liu,Zhandong Liu

doi:10.3390/agronomy10081136

Abstract

Silicon (Si) enhances maize resistance to drought. While previous studies have mainly focused on the seedling stage, the mediation of drought stress by Si imposed at the vegetative and reproductive stages has been rarely investigated. A soil-column experiment was thus conducted under a rainproof shelter to quantify the effect s of Si application on the physiological and agronomic responses of maize to drought stress imposed at the 6-leaf (D-V6), 12-leaf (D-V12), and blister (D-R2) stages. The observed parameters included plant growth, photosynthesis, osmolytes, antioxidant activity, and grain yield. The results showed that drought stress strongly decreased the leaf area, leaf water content, photosynthetic rate, chlorophyll content, and antioxidant activity (superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT)) and markedly increased lipid peroxidation. D-V6, D-V12, and D-R2 decreased grain yields by 12.9%, 28.9%, and 44.8%, respectively, compared to the well-watered treatment (CK). However, Si application markedly increased leaf area, chlorophyll content, photosynthetic rate, osmolyte content, and enzymatic antioxidant activities (SOD, POD, and CAT), and decreased malondialdehyde (MDA) and superoxide radical accumulation, ultimately improving maize yields by 12.4%, 69.8%, and 80.8%, respectively, compared to the non-Si treated plants under drought stress at the V6, V12, and R2 stages. Furthermore, maize yields had a significant positive correlation with chlorophyll content and SOD and POD activity during the three stages. Our findings suggest that Si-induced changes in chlorophyll content and antioxidant activity might constitute important mechanisms for mitigating drought stress. In conclusion, this study provides physico-biochemical evidence for the beneficial role of Si in alleviating drought-induced yield reduction in maize, particularly during the late vegetative or early reproductive stages. Thus, Si application constitutes an effective approach for improving maize yield in rain-fed agricultural systems.

Highlights

Drought significantly threatens crop productivity and food security worldwide, in arid and semiarid regions [1]
The growth of D-V6 plants was enhanced after re-watering compared with the CK treatment
Silicon application had no significant effect on plant height, leaf area and leaf water content under the well-watered condition (CK) across the tested growth stages

Summary

Introduction

Drought significantly threatens crop productivity and food security worldwide, in arid and semiarid regions [1]. Effective strategies for improving plant resistance to drought stress are urgently required [4]. Numerous studies have demonstrated that Si is beneficial for alleviating drought stress in various species, including wheat [8], maize [9], soybean [10], rice [11], sorghum [12], and mango [13]. The enhanced drought resistance associated with Si is mainly believed to be related to reduced transpiration capacity [9], increased water uptake by the roots [14], the alleviation of oxidative damage [15], and decreased osmotic potential [12]. Studies on the effects of Si application on plant transpiration and stomatal conductance under drought stress have contradictory findings [9,14,16] and the fundamental mechanisms for Si-mediated drought tolerance have not been sufficiently elucidated

Methods

Results

Discussion

Conclusion