Effects of Organic Polymer Compound Material on K+ and Na+ Distribution and Physiological Characteristics of Cotton Under Saline and Alkaline Stresses

Abstract

Soil salinization and alkalization greatly restrict crop growth and yield. In this study, NaCl (8 g kg−1) and Na2CO3 (8 g kg−1) were used to create saline stress and alkaline stress on cotton in pot cultivation in the field, and organic polymer compound material (OPCM) and stem girdling were applied before cotton sowing and at flowering and boll-forming stage, respectively, aiming to determine the effects of OPCM on K+ and Na+ absorption and transport and physiological characteristics of cotton leaf and root. The results showed that after applying the OPCM, the Na+ content in leaf of cotton under saline stress and alkaline stress were decreased by 7.72 and 6.49%, respectively, the K+/Na+ ratio in leaf were increased by 5.65 and 19.10%, respectively, the Na+ content in root were decreased by 9.57 and 0.53%, respectively, the K+/Na+ ratio in root were increased by 65.77 and 55.84%, respectively, and the transport coefficients of K+ and Na+ from leaf to root were increased by 39.59 and 21.38%, respectively. The activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), and the relative electrical conductivity (REC) in cotton leaf were significantly increased, while the content of malondialdehyde (MDA) was decreased; but the changes in those in root were not significant. The boll weights were increased by 11.40 and 13.37%, respectively, compared with those for the control. After stem girdling, the application of OPCM still promoted the ion transport of cotton organs; moreover, the CAT activity in root was increased by 25.09% under saline stress, and the SOD activity in leaf and CAT in root were increased by 42.22 and 6.91%, respectively under alkaline stress. Therefore, OPCM can significantly change the transport of K+ and Na+ to maintain the K+ and Na+ homeostasis in leaf and root, and regulate physiological and biochemical indicators to alleviate the stress-induced damage. Besides, the regulation effect of OPCM on saline stress was better than that on alkaline stress.

Transcriptome and Metabolome Analyses of Salt Stress Response in Cotton (Gossypium hirsutum) Seed Pretreated with NaCl

“…Specific sensors in the plasma membrane perceive the stress information and, consequently, many signal molecules are usually produced and transduced through the nucleus to activate stress-responsive TFs for the initiation of transcriptional reprogramming [14,66,67]. Higher concentrations of Na + ions induce membrane disintegration, reduced growth and cell division, osmotic imbalance, less photosynthesis, and the production of ROS [6,68,69]. The current study investigated fresh root and shoot weights, as well as emergence percentages, all of which displayed significant differences between the samples treated with 3% NaCl for 0.5, 1, and 1.5 h. The analysis of variance, PCA, and correlation analyses of the phenotypic, transcriptomic, and metabolomic data exposed significant differences between the treatments and control, which lay the foundation for further study.…”

“…The increasing amount of NaCl, MgCl 2 , and CaCl 2 as a consequence of many activities, such as wastewater treatment, freshwater channel alterations, or deicing of roads with salt applications is deteriorating the natural environment [2,3]. Tolerance against abiotic stress involves a consortium of several different biological processes [4][5][6][7]. The major essential systems involved are stress signaling, osmotic adjustment, antioxidant metabolism, hormone metabolism, and others [8].…”

“…These TFs trigger the production of salt-responsive proteins in the plant by switching on the respective genes that consequently enhance tolerance against the saline environment [4]. Moreover, the activation of the regulatory mechanism in response to saline stress occurs, which is a signaling pathway for salt sensitivity (SOS) that primarily controls potassium (K + )/sodium (Na + ) homeostasis [6,12,13]. The capability of plants to tolerate salinity varies among different species, indicating the presence of varying salt stress regulatory mechanisms [5,14].…”

“…Understanding the response of the cotton crop to salt, its tolerance mechanism, and comprehensive knowledge related to management practices may be helpful [1,17]. Recently, many advanced studies, such as whole-genome sequencing, on different cotton species (diploid and tetraploid) facilitated us with the reference genome(s) of cotton for a better understanding of genes and transcription factors in relation to their functions under stress conditions in terms of controlling several biological and metabolic pathways [2,6,14,[16][17][18][19][20].…”

“…Salt stress ultimately affects crop productivity by inhibiting growth, delaying flowering, lowering fruiting nodes, fruit shedding, and lowering the boll weight. Depression in metabolic enzyme activities, including cytokinins, salicylic acid, alkaline invertase, acidic invertase, and sucrose phosphate synthase, may deteriorate the fiber quality under salt stress [2,6,27]. The molecular mechanism behind this tolerance can logically be understood by detecting and examining the genes expressed when the plant roots experience salinity in their growing medium/environment.…”