Comparative Performance of Multivariable Agro-Physiological Parameters for Detecting Salt Tolerance of Wheat Cultivars under Simulated Saline Field Growing Conditions

Abstract

Field-based trials are crucial for successfully achieving the goals of plant breeding programs aiming to screen and improve the salt tolerance of crop genotypes. In this study, simulated saline field growing conditions were designed using the subsurface water retention technique (SWRT) and three saline irrigation levels (control, 60, and 120 mM NaCl) to accurately appraise the suitability of a set of agro-physiological parameters including shoot biomass, grain yield, leaf water relations, gas exchange, chlorophyll fluorescence, and ion accumulation as screening criteria to establish the salt tolerance of the salt-tolerant (Sakha 93) and salt-sensitive (Sakha 61) wheat cultivars. Shoot dry weight and grain yield per hectare were substantially reduced by salinity, but the reduction was more pronounced in Sakha 61 than in Sakha 93. Increasing salinity stress caused a significant decrease in the net photosynthesis rate and stomatal conductance of both cultivars, although their leaf turgor pressure increased. The accumulation of toxic ions (Na+ and Cl-) was higher in Sakha 61, but the accumulation of essential cations (K+ and Ca2+) was higher in Sakha 93, which could be the reason for the observed maintenance of the higher leaf turgor of both cultivars in the salt treatments. The maximum quantum PSII photochemical efficiency (Fv/Fm) and the PSII quantum yield (ΦPSII) decreased with increasing salinity levels in Sakha 61, but they only started to decline at the moderate salinity condition in Sakha 93. The principle component analysis successfully identified the interrelationships between all parameters. The parameters of leaf water relations and toxic ion concentrations were significantly related to each other and could identify Sakha 61 at mild and moderate salinity levels, and, to a lesser extent, Sakha 93 at the moderate salinity level. Both cultivars under the control treatment and Sakha 93 at the mild salinity level were identified by most of the other parameters. The variability in the angle between the vectors of parameters explained which parameters could be used as individual, interchangeable, or supplementary screening criteria for evaluating wheat salt tolerance under simulated field conditions.

Multidimensional Evaluation for Detecting Salt Tolerance of Bread Wheat Genotypes Under Actual Saline Field Growing Conditions

“…The former stress diminishes the plants’ ability to benefit from water, similar to water-deficit-induced stress [ 10 , 11 ]. However, the latter stress leads to an energy problem in plants due to a significant reduction in photosynthetic capacity, different metabolic functions, and cell elongation [ 12 , 13 , 14 , 15 , 16 ]. Moreover, salinity stress leads to nutrient imbalance by reducing uptake of essential elements, particularly K + , Mg 2+ , and Ca 2+ , which causes ion imbalance at cellular and tissue levels [ 15 , 17 ].…”

Ability of Modified Spectral Reflectance Indices for Estimating Growth and Photosynthetic Efficiency of Wheat under Saline Field Conditions

“…Of the multiple physiological variables that result in a considerable decline in biomass production of plant under salt stress, gas exchange mechanisms and the photosynthetic capacity are the most important. Dramatic changes in leaf turgor pressure and a K + content deficit in leaf tissue under salt stress conditions lead to a significant decline in stomatal conductance (Gs), which then adversely affects photosynthesis (Pn) and transpiration (E) rates [1,2]. It is thus necessary to monitor the responses of these physiological variables to salt stress to enable improvements in the salt tolerance of wheat genotypes or apply appropriate agronomic management practices that alleviate the adverse impacts of salt stress, with the ultimate aim of providing sustainable crop production under salinity stress conditions.…”

Detecting Salt Tolerance in Doubled Haploid Wheat Lines

“…This is because this method can be applied on a large scale, can provide a long-term solution, and is inexpensive for poor farmers. However, success in improving salt tolerance of genotypes has been limited by a number of factors, such as limited sources of genetic diversity in breeding programs, low selection efficiency using simultaneous morpho-physiological and biochemical parameters as screening criteria, and the lack of effective evaluation methods to detect salt tolerance of genotypes using overall salinity levels and multivariable screening criteria [2][3][4][5][6].Many studies investigated the tolerance of wheat (Triticum aestivum L.) into the salinity and found that the tolerated genotypes can survive in the level of 150 mM NaCl [3,5]. High salinity lowers agricultural productivity.…”

“…Multivariate analysis is a useful tool for identifying sources of genetic variation and discriminating their salt tolerance using accurate and multiple selection criteria. Therefore, a multivariate analysis combining morphological, physiological, and biochemical traits would be most appropriated [2,6,24,38].Therefore, the aims of our study were to characterize the genetic variance, heritability, and expected genetic advances of different traits as screening criteria for evaluating the salt tolerance of DHL genotypes under different salinity conditions. In addition, particular attention was paid to investigate the efficiency of using multivariable morpho-physiological and biochemical parameters as well as to identify traits that can be employed as credible screening criteria for the selection and improvement of salt tolerance in wheat.…”

“…Multivariate analysis is a useful tool for identifying sources of genetic variation and discriminating their salt tolerance using accurate and multiple selection criteria. Therefore, a multivariate analysis combining morphological, physiological, and biochemical traits would be most appropriated [2,6,24,38].…”