Osmotic & specific effects of excess salts on beans.

摘要: In analyzing the cause of growth depression plants raised under saline conditions, a distinction can be made between effects that are specific and those non-specific, with respect to different salt species present in root environment (1). Non-specific related total concentration salts, regardless species. They prevail among factors determine partial molar free energy water, from gradients which depend magnitude driving force, as well direction pertinent translocation water both soils plants. Known osmotic effects, nonspecific salts physico-chemical nature where they refer nutrient or soil-solution. barely distinguishable physiological influence state within plants, it may have bearing on cell processes. Both types associated extent capable adjusting their internal pressure (OP) relative changes brought about external OP (6, 8). Specific usually due concentrations various ion one another, less frequently absolute level any element. Their is essentially nature. Changes plant cells by varying medium kept at constant should also recognized effects. Osmotic confounded because high total-salt levels normally occur association ionic conditions unbalanced nutrition. Other like trace element toxicities, unrelated (27). many solution-culture studies purporting separate impact single (8, 9), mixtures (15), organic compounds (10), been used control solutions. Isosmotic solutions containing NaCl, Na,SO4, CaCl2, caused equal depressions kidney beans (9), uptake corn roots (10). were linearly three solution. To isosmotic depressions, such examples cited, predominant. Less likely, though sometimes not impossible, alternative explanation test nearly similar. Any variation response indicates additional significance For instance, MgCl2 MgSO4 depressed significantly more than did CaCl9, all being compared concentrations. No proportionality existed Mg-salt (9). With guayule plant, neither was there five mentioned, nor when same. fact, appeared MgCl most, CaCl least, toxic (24). Attempts distinguish require aid compound that, while lowering same time itself inert possible metabolism tested. The latter requirement has always sufficiently considered. Substances polyvinylpyrrolidone (26) polyvinyl alcohol (5) equivalent 1 atm observed dwarf red (11). substances, sucrose, either actively taken up or, mannitol, subject quick microbiological degradation. usefulness mentioned for extended length dubious. A search an osmoticum desired qualities resulted selection Carbowax polyethylene glycol, molecular weight 20,000, marketed Union Carbide Chemicals Co. This henceforth will referred C20M. glycols lower weights applied purposes, but no observations reported regard toxicity (16). C20M contains considerable amounts aluminum magnesium These impurities would removed prior applying most Our paper details application dialyzed I Received February 23, 1961.