Low apoplastic Na(+) and intracellular ionic homeostasis confer salinity tolerance upon Ca(2)SiO(4) chemigation in Zea mays L. under salt stress.

Salinity is known to have a greater impact on shoot growth than root growth. Na+ buildup in plant tissue under salt stress has been proposed as one of the main issues that causes growth inhibition in crops via ionic imbalances, osmotic stress and pH disturbances. However, the evidence for apoplastic Na+ buildup and the role of silicon in Na+ accumulation at the subcellular level is still enigmatic. The current study focuses on the accumulation of Na+ in the apoplast and symplast of younger and older leaves of two maize varieties (Iqbal as salt-tolerant and Jalal as salt-sensitive) using hydroponic culture along with silicon supplementation under short-term salinity stress. Subcellular ion analysis indicated that silicon nutrition decreased Na+ concentration in both apoplastic washing fluid and symplastic fluid of maize under salt stress. The addition of silicon under NaCl treatment resulted in considerable improvement in fresh biomass, relative water content, chlorophyll content, and concentration of important subcellular ions (i.e., Ca2+, Mg2+, and K+). Knowledge of subcellular ion analysis is essential for solving the mechanisms underlying vital cellular functions e.g. in the current study, the soluble Na+ concentration in the apoplast of older leaves was found to be significantly greater (36.1 mM) in the salt-sensitive variety under NaCl treatment, which was 42.4% higher when compared to the Na+ concentration in the salt-tolerant variety under the same treatment which can influence permeability of cell membrane, signal transduction pathways and provides insights into how ion compartmentalization can contributes to salt tolerance. Calcium silicate enrichment can contribute to increased growth and improved ionic homeostasis by minimizing leaf electrolyte leakage, improving mechanical functions of cell wall and reducing water loss, and improved photosynthetic function. In current investigation, increased water content and intracellular ionic homeostasis along with reduced concentration of Na+ in the maize leaf apoplast suggest that calcium silicate can be used to ameliorate the adverse effects of salt stress and obtain yield using marginal saline lands.

众所周知，盐度对地上部分生长的影响比对根系生长的影响更大。盐胁迫下植物组织中钠离子的积累被认为是通过离子失衡、渗透胁迫和酸碱度失调导致作物生长受抑制的主要问题之一。然而，质外体钠离子积累的证据以及硅在亚细胞水平上对钠离子积累的作用仍然是个谜。本研究采用水培法，并在短期盐胁迫下添加硅，重点研究了两个玉米品种（耐盐品种伊克巴尔和盐敏感品种贾拉尔）的幼叶和老叶质外体和共质体中钠离子的积累情况。亚细胞离子分析表明，在盐胁迫下，硅营养降低了玉米质外体洗涤液和共质体中钠离子的浓度。在氯化钠处理下添加硅，使鲜生物量、相对含水量、叶绿素含量以及重要亚细胞离子（如钙离子、镁离子和钾离子）的浓度有了显著提高。亚细胞离子分析的知识对于阐明重要细胞功能的机制至关重要，例如在本研究中，在氯化钠处理下，盐敏感品种老叶质外体中的可溶性钠离子浓度（36.1毫摩尔）显著更高，与相同处理下耐盐品种的钠离子浓度相比高出42.4%，这会影响细胞膜的通透性、信号转导途径，并有助于深入了解离子区隔化如何有助于提高耐盐性。硅酸钙的富集可以通过减少叶片电解质渗漏、改善细胞壁的机械功能和减少水分流失以及提高光合功能，来促进生长并改善离子内稳态。在本次研究中，玉米叶片质外体中含水量增加、细胞内离子内稳态改善以及钠离子浓度降低，表明硅酸钙可用于缓解盐胁迫的不利影响，并利用边缘盐碱地获得产量。