Physiological Responses to Salinity in Selected Lines of Wheat

Abstract

Two selections of bread wheat, Triticum aestivum L, differing in their relative salt resistance, were grown in salinized solution culture, and relative growth rates, osmotic adjustment, ion accumulation, and photosynthesis were monitored to study the responses of the plants to salinity.Differences in water relations were minimal and were only apparent for 3 days following salinization. The lines differed substantially in their relative growth rates and photosynthetic responses for several weeks following salinization, despite full osmotic adjustment. Concentrations of major cations and Cl in the plant organs were remarkably similar in both lines, indicative of minimal differences in gross ion absorption and translocation.The authors interpret these results to suggest that the major difference between these two lines of wheat was their response to specific ion effects, at the level of the organ, tissue, cell, and subcellular entities. Superior compartmentation oftoxic ions by the more salt-tolerant line, presumably in the vacuole, might have enabled it to maintain its cytoplasmic metabolic apparatus in a stabler and more nearly normal state than the sensitive line was able to do; a measure of true cytoplasmic toleration of salt may also be a factor.Salinity is a major problem in today's irrigation agriculture, as millions of tons of salt are annually dumped onto the soil from the irrigation water. Plants vary, however, in their ability to cope with salinity, as is evidenced by the wide diversity of plant habitats, ranging from nonsaline environments to the extreme salinities of the sea, salt marshes, and saline deserts. For crop plants, differences in salt resistance exist not only among different genera and species, but even within a species which may on the whole be considered salt sensitive (Ref. 6, Refs. 8,9, and 18). These observations support two arguments: (a) crop plants can be adapted to saline environments, and (b) intraspecific variation can be exploited to investigate the nature of salt resistance or sensitivity (9). It is the second of these claims that is addressed in the current study.The reduction in yield of many crops by salinity is well documented (18 mechanisms of salt tolerance (7,(10)(11)(12)19).In this paper, we report the results of a study of the physiological responses to salinity, comparing a salt-resistant line of hexaploid wheat with one which is salt-sensitive. The use of intraspecific selections in comparative studies should provide a powerful tool to unveil the genetically based mechanisms of salt resistance (9). This investigation was not meant to be exhaustive, but rather exploratory in nature, as an attempt to find the areas of greatest difference between the selections which might relate to the observed differences in salt resistance. MATERUILS AND METHODS Selection and Culture of Salt-Resistant and Salt-SensitiveWheat. Details of the selection procedures have been reported elsewhere (15). In general, lines from the world collection of wheat, Triticum aestivum L., were ...

Early Effects of Salinity on Nitrate Assimilation in Barley Seedlings

“…When compamd at the same concentration, S042-salts inhibited N03-uptake more than did Cl-salts (Table III); hence, the absolute concentrations of each ion seem more important as inhibitors of NO3-uptake than does the osmolality ofthe solutions. Kingsbury et al (18) observed that specific ion effects were more important than was osmotic stress as factors influencing adaptation to salt.…”

Effect of salinity on growth and solute accumulation in two wheat lines differing in salt tolerance

“…In contrast, Schachmann and Munns (1992) reported that Na exclusion was a general characteristic of salt tolerance in wheat lines, whereas salt-tolerant lines display much higher shoot Na levels than the sensitive lines. Varietal differences in growth response to salinity in wheat leaves were not related to differences in salt accumulation in leaves, but to differences in osmotically induced reduction in water availability under salinity stress (Kingsbury et al 1984).…”

photosynthesis in the 7H Asakaze komugi/Manas wheat/barley addition line during salt stress

“…Salt stress is considered to be an important environmental factor, limiting plant growth and productivity in today's agriculture (Boyer, 1982;Kingsbury et al, 1984;Belkhodja et al, 1999;Allakhverdiev et al, 2000), especially in arid or semi-arid regions (Siler et al, 2007) or irrigated areas (Szabolcs, 1994). In crop plants several life processes are particularly sensitive to soil and water salinity, since high salt concentration has a threefold effect: it limits water availability to the roots (osmotic stress); it can cause ionic stress when the salt is 368 taken up by plants; and it also influences nutrient uptake and translocation (Bagci, 2003;Siler et al, 2007).…”