Effect of Water Deficit Stress on Seedling Biomass and Physio-Chemical Characteristics in Different Species of Wheat Possessing the D Genome

Abstract

Wild relatives of wheat serve as an extraordinary source of variability for breeding programs due to their capabilities to respond to various environmental stresses. Here, we investigated some species possessing a D genome (T. aestivum, Ae. tauschii, Ae. crassa and Ae. cylindrica) in terms of relative water content (RWC), stomatal conductance (Gs), relative chlorophyll content, initial fluorescence (Fo), maximum quantum yield of PSII (Fv/Fm), maximum primary yield of PSII photochemistry (Fv/Fo), as well as shoot fresh and dry biomasses under control and water deficit conditions. Our results revealed that water deficit negatively affected all traits; shoot fresh weight, Gs and RWC showed the highest reduction compared to the control condition. Principal component analysis (PCA) identified two PCs that accounted for 53.36% of the total variation in the water deficit conditions. Correlation analysis and PCA-based biplots showed that stress tolerance index (STI) is significantly associated with Fv/Fm and Fv/Fo under water stress conditions, suggesting that these are the best parameters to evaluate when screening for tolerant samples at the seedling stage. We identified 19 accessions from Ae. crassa and one from Ae. tauschii as the most tolerant samples. In conclusion, Ae. crassa might provide an ideal genetic resource for drought-tolerant wheat breeds.

Effects of Drought Stress on Some Agronomic and Morpho-Physiological Traits in Durum Wheat Genotypes

“…This result indicates that some of the tested genotypes (especially G9) may have a strong capacity to protect themselves through maintenance of high levels of PSII activity. Although several studies reported that drought stress reduces Fv/Fm [1,17,29], our results revealed that the process of energy displacement from the antenna chlorophyll complex to the PSII may not be affected by drought stress in some of the tested genotypes. The stomatal conductance (Gs) as a physiological trait has two important roles: (1) maintenance of water in leaf tissue by control of transpiration, and (2) determining the rate of gas exchange by movement of gases between the inner and outer environments of the leaf tissue.…”

“…Among the yield-based indices, STI is a suitable index for characterization of the most tolerant to drought stress. Indeed, its applicability has been confirmed in numerous studies [1,17,22,29,35,38,41,42]. Based on the three-dimensional plots, several different genotypes were distributed in Group A each year ( Figure S2).…”

“…Among the various environmental stresses, drought is the major detrimental factor for growth and productivity [17]. The development of high-yielding cultivars with acceptable stability and adaptability across different environments is one promising strategy for improving wheat yield under drought-prone environments [18].…”

“…Although many agronomic, morphological, and physiological traits have been studied for their use in breeding programs for drought tolerance, only a few traits are currently recommended for application in practical programs. For instance, several traits such as stay-green character [31], canopy temperature and spike fertility [32], number of grains per plot [33], stomatal conductance and relative chlorophyll content [17,29], water use efficiency [34], root architecture [35], chlorophyll fluorescence [17,29,36] were used as selection indicators due to their correlations with grain yield under drought conditions. In the present study, a positive correlation between grain yield and other phenological characteristics (number of days to spike heading, physiological maturity, and grain filling period), as well as number of spikes per plant, biomass, and harvest index under drought conditions were found.…”

Physio-Morphological and Biochemical Trait-Based Evaluation of Ethiopian and Chinese Wheat Germplasm for Drought Tolerance at the Seedling Stage

“…Depending on the growth stage, intensity and duration of the stress, and nature of plant stress response mechanisms; drought stress causes a decrease in RWC, chlorophyll degradation, stomatal closure, increased osmolytes, and growth inhibition in wheat [32][33][34][35] which ultimately leading to yield loss and productivity. Previous reports demonstrated that water deficit (drought stress) in wheat [36,37] has unfavorable effects on the efficiency of photosystem II (PSII), as indicated by changes in chlorophyll florescence (CF) [38] parameters such as initial fluorescence (Fo), maximum quantum yield of PSII (Fv/Fm), maximum primary yield of PSII photochemistry (Fv/Fo), as well as plant growth and dry matter. Therefore, understanding crop stress physiology and its related tools such as chlorophyll fluorescence (CF) has become known as a useful indicator for investigating stress in plants in vivo [39].…”