Hammami Zied, Tounsi-Hammami Soumaya, Nhamo Nhamo, Rezgui Saleh, Trifa Yousef
Crop Diversification and Genetics Section, International Center for Biosaline Agriculture, Dubai, United Arab Emirates.
Department of Life and Environmental Sciences, College of Natural and Health Sciences at Zayed University, Dubai, United Arab Emirates.
Front Plant Sci. 2024 May 28;15:1324388. doi: 10.3389/fpls.2024.1324388. eCollection 2024.
In the Near East and North Africa (NENA) region, crop production is being affected by various abiotic factors, including freshwater scarcity, climate, and soil salinity. As a result, farmers in this region are in search of salt-tolerant crops that can thrive in these harsh environments, using poor-quality groundwater. The main staple food crop for most of the countries in this region, Tunisia included, is barley.
The present study was designed to investigate the sensitivity and tolerance of six distinct barley genotypes to aridity and salinity stresses in five different natural field environments by measuring their photosynthetic activity.
The results revealed that tolerant genotypes were significantly less affected by these stress factors than sensitive genotypes. The genotypes that were more susceptible to salinity and aridity stress exhibited a significant decline in their photosynthetic activity. Additionally, the fluorescence yields in growth phases J, I, and P declined significantly in the order of humid environment (BEJ), semi-arid site (KAI), and arid environment (MED) and became more significant when salt stress was added through the use of saline water for irrigation. The stress adversely affected the quantum yield of primary photochemistry (φP0), the quantum yield of electron transport (φE0), and the efficiency by trapped excitation (ψ0) in the vulnerable barley genotypes. Moreover, the performance index (PI) of the photosystem II (PSII) was found to be the most distinguishing parameter among the genotypes tested. The PI of sensitive genotypes was adversely affected by aridity and salinity. The PI of ICARDA20 and Konouz decreased by approximately 18% and 33%, respectively, when irrigated with non-saline water. The reduction was even greater, reaching 39%, for both genotypes when irrigated with saline water. However, tolerant genotypes Souihli and Batini 100/1B were less impacted by these stress factors.The fluorescence study provided insights into the photosynthetic apparatus of barley genotypes under stress. It enabled reliable salinity tolerance screening. Furthermore, the study confirmed that the chlorophyll a fluorescence induction curve had an inflection point (step K) even before the onset of visible signs of stress, indicating physiological disturbances, making chlorophyll fluorescence an effective tool for identifying salinity tolerance in barley.
在近东和北非（NENA）地区，作物生产正受到各种非生物因素的影响，包括淡水稀缺、气候和土壤盐度。因此，该地区的农民正在寻找能够在这些恶劣环境中利用劣质地下水茁壮成长的耐盐作物。该地区包括突尼斯在内的大多数国家的主要主食作物是大麦。
本研究旨在通过测量六种不同大麦基因型在五种不同自然田间环境中的光合活性，来研究它们对干旱和盐胁迫的敏感性和耐受性。
结果表明，耐盐基因型受这些胁迫因素的影响明显小于敏感基因型。对盐度和干旱胁迫更敏感的基因型其光合活性显著下降。此外，在生长阶段J、I和P的荧光产量按照湿润环境（BEJ）、半干旱地区（KAI）和干旱环境（MED）的顺序显著下降，并且当通过使用盐水灌溉添加盐胁迫时变得更加显著。胁迫对易受影响的大麦基因型的初级光化学量子产率（φP0）、电子传递量子产率（φE0）和捕获激发效率（ψ0）产生了不利影响。此外，发现光系统II（PSII）的性能指数（PI）是所测试基因型中最具区分性的参数。敏感基因型的PI受到干旱和盐度的不利影响。用非盐水灌溉时，ICARDA20和Konouz的PI分别下降了约18%和33%。当用盐水灌溉时，这两个基因型的下降幅度更大，达到39%。然而，耐盐基因型Souihli和Batini 100/1B受这些胁迫因素的影响较小。荧光研究为胁迫下大麦基因型的光合机构提供了见解。它能够进行可靠的耐盐性筛选。此外，该研究证实，叶绿素a荧光诱导曲线甚至在胁迫的可见迹象出现之前就有一个拐点（K点），表明生理紊乱，这使得叶绿素荧光成为鉴定大麦耐盐性的有效工具。
