With the global climate anomalies and the destruction of ecological balance, the water shortage has become a serious ecological problem facing all mankind, and drought has become a key factor restricting the development of agricultural production. Therefore, it is essential to study the drought tolerance of crops. Based on previous studies, we reviewed the effects of drought stress on plant morphology and physiology, including the changes of external morphology and internal structure of root, stem, and leaf, the effects of drought stress on osmotic regulation substances, drought-induced proteins, and active oxygen metabolism of plants. In this paper, the main drought stress signals and signal transduction pathways in plants are described, and the functional genes and regulatory genes related to drought stress are listed, respectively. We summarize the above aspects to provide valuable background knowledge and theoretical basis for future agriculture, forestry breeding, and cultivation.

Response Mechanism of Plants to Drought Stress

Evaluation of morphological, physiological, and biochemical traits for assessing drought resistance in eleven tree species.

Salinity is a leading threat to crop growth throughout the world. Salt stress induces altered physiological processes and several inhibitory effects on the growth of cereals, including wheat (Triticum aestivum L.). In this study, we determined the effects of salinity on five spring and five winter wheat genotypes seedlings. We evaluated the salt stress on root and shoot growth attributes, i.e., root length (RL), shoot length (SL), the relative growth rate of root length (RGR-RL), and shoot length (RGR-SL). The ionic content of the leaves was also measured. Physiological traits were also assessed, including stomatal conductance (gs), chlorophyll content index (CCI), and light-adapted leaf chlorophyll fluorescence, i.e., the quantum yield of photosystem II (Fv′/Fm′) and instantaneous chlorophyll fluorescence (Ft). Physiological and growth performance under salt stress (0, 100, and 200 mol/L) were explored at the seedling stage. The analysis showed that spring wheat accumulated low Na+ and high K+ in leaf blades compared with winter wheat. Among the genotypes, Sakha 8, S-24, W4909, and W4910 performed better and had improved physiological attributes (gs, Fv′/Fm′, and Ft) and seedling growth traits (RL, SL, RGR-SL, and RGR-RL), which were strongly linked with proper Na+ and K+ discrimination in leaves and the CCI in leaves. The identified genotypes could represent valuable resources for genetic improvement programs to provide a greater understanding of plant tolerance to salt stress.

Effect of Salinity Stress on Physiological Changes in Winter and Spring Wheat

Metabolic regulation is the key mechanism implicated in plants maintaining cell osmotic potential under drought stress. Understanding drought stress tolerance in plants will have a significant impact on food security in the face of increasingly harsh climatic conditions. Plant primary and secondary metabolites and metabolic genes are key factors in drought tolerance through their involvement in diverse metabolic pathways. Physio-biochemical and molecular strategies involved in plant tolerance mechanisms could be exploited to increase plant survival under drought stress. This review summarizes the most updated findings on primary and secondary metabolites involved in drought stress. We also examine the application of useful metabolic genes and their molecular responses to drought tolerance in plants and discuss possible strategies to help plants to counteract unfavorable drought periods.

https://www.mdpi.com/1422-0067/22/17/9108/pdf

Metabolomics and Molecular Approaches Reveal Drought Stress Tolerance in Plants.

Limited water stress is one of the most important environmental stresses that affect the growth, quantity and quality of agronomic crops. This study was undertaken to investigate the effect of foliar applied salicylic acid (SA) on physiological responses, antioxidant enzymes and qualitative traits of Cucurbita pepo L. Plants exposed to water-stressed conditions in two years of field studies. Irrigation regimes at three soil matric potential levels (−0.3, −1.2 and −1.8 MPa) and SA at four levels (0.0, 0.5, 1.0 and 1.5 mg/L) were considered as main plot and sub-plots, respectively. The soil matric potential values (MPa) was measured just before irrigation. Results showed that under water stressed conditions alone, the amounts of malondialdehyde (MDA), hydrogen peroxide (H2O2) and ion leakage were higher compared with control treatment. However, spraying of SA under both water stress and non-stress conditions reduced the values of the above parameters. Water stress increased CAT, APX and GR enzymes activity. However foliar application of SA led to the decrease of CAT, APX and GR under all soil matric potential levels. The amount of carbohydrates and fatty acids increased with the intensity of water stress and SA modulated this response. By increasing SA concentration both in optimum and stress conditions, saturated fatty acids content decreased. According to our data, the SA application is an effective approach to improve pumpkin growth under water stress conditions.

/pdf/physiological-and-qualitative-response-of-cucurbita-pepo-l-2mknkcf1.pdf

Ah Reum Han

Papers

Responses to drought stress in Prunus sargentii and Larix kaempferi seedlings using morphological and physiological parameters

Evaluation of morphological, physiological, and biochemical traits for assessing drought resistance in eleven tree species.