The effect of NaCl salinity and water stress with polyethylene glycol on nitrogen fixation, stomatal response and transpiration of Medicago sativa, Trifolium repens and Trifolium brachycalycinum (subclover)

Abstract

1982. The effect of NaCl salinity and water stress with polyethylene glycol on nitrogen fixation, stomatal response and transpiration of Medicago sativa, Trifolium repens and Trifolium brachycalycinum (subclover). -Physio). Plant. 54: 361-366.The objective of this study was to investigate the behaviour of different leg,umes against salinity and water stress, thus trying to discover simultaneous adaptations to both stresses. The nitrogen fixation, transpiration, predawn leaf water potential, and stomatal response of Medicago .sativa L. (cvs. Tierra de Campos and Aragon), Trifolium repens L. (cv. Aberystw^th S-184) and T. brachycalycinum Katzn. et Morley (= T. subterraneum L. cv. Clare) were compared at three levels of stress (0.05,, 0.3 and 0.5 MPa of either Nad or polyethylene glycol 6000) in nutrient solution. The plants were stressed for three days and then returned to control nutrient solution.The changes in the parameters analyzed were dependent on the proportion of stress treatments and the nature of the species, always being greater in plants from PEG than from NaCl solutions. Transfer of lucerne and subclover plants from NaCl at 0.05 MPa to a non-saline medium resulted in an increase of nitrogen fixation above the level of the non-salinized control plants, especially significant in lucerne. Analysis of possible inorganic impurities in comnnercial PEG suggest that such type of impurities are not responsible for the toxic effects reported. Plant damage resulting from PEG treatment was apparently due to penetrations of PEG (as determined qualitatively by using the letraiodinebismuthic acid technique) or low-molecular organic impurities into the plant. -The results are discussed as part of the adaptation of the different species to salinity aijd water stress. The best performance was given by "Tierra de Campos". ,straints are not only common in arid and semiarid rer lie ion gions but also in mild, hutnid climates where drought Nitrogen fixatioti efficiency is greatly altered by en-(which occurs at random throughout the growing seavironmental impact on both host atid bacterium, but son. Decker -in press) and salinity (increasingly imlittle is curretitly knowti about combinations of legumes portant by agricultural practice) cause substantial reand Rhizobium nitrogen-fixing bacteria that are resis-duction in growth atid yield. tant to drought and salinity. These environmental con-In the last years dramatic progress has been made in

Comparative effects of NaCl and polyethylene glycol on root distribution, growth, and stomatal conductance of sour orange seedlings

“…1). These results agreed with those of Plaut and Federman (1985) and with Sanchez-Diaz et al (1982) who found that P E G decreased leaf conductance and carbon dioxide fixation rates in tomato and legumes more severely than did NaC1. Reduction in stomatal conductance due to NaC1 was found to be associated with accumulation of sodium in the leaves (Walker et al, 1983).…”

“…Polyethylene glycol (PEG) compounds have been widely used to simulate water stress effects in plants. Several investigators have examined the effects of NaCI and PEG on growth and ion absorption in bean, maize, sorghum (Kawasaki et al, 1983a), barley (Kawasaki et al, 1983b), legumes (Sanchez-Diaz et al, 1982), and tomato * Florida Agricultural Experiment Station Journal Series No. 9941.…”

Effects of environmental factors on cereal starch biosynthesis and composition

“…High salt concentrations cause osmotic stress after short-term exposure or ion toxicity after long-term exposure in plants (Munns and Tester, 2008;Sanchez-Diaz et al, 1982;Zeng, 2005). Sodium chloride (NaCl) is the salt of main concern due to its high solubility (Munns and Tester, 2008) with 40 mM considered problematic for agriculture (Munns and Tester, 2008).…”

Phytosterol of Potamogeton maackianus and its change under the stress of Microcystis aeruginosa

“…Along with the algal concentration going up, 24-ethyl sterol (sitosterol and stigmasterol) content in plants increased more than that of 24-methyl sterol (campesterol), moreover, the ratio between campesterol and stigmasterol plus sitosterol decreased from 18.5% to 16.2%, which showed that M. aeruginosa affected the second alkyl side chain at C-24 position of plant sterol in the biosynthesis process of sterol in vivo P. maackianus [24][25][26][27] . The first deteriorative change during stress injury is an alteration in the structure and function of cell membranes, which results in an impaired ability to retain solutes [28] . The structure and function of cell membranes would be influenced by sterols [26] .…”