The effect of salt additions to the substrate on intake of water and nutrients by roots of approach-grafted tomato plants

The effect of salt additions to the substrate on intake of water and nutrients by roots of approach-grafted tomato plants

1943

REP.TM-0953

The roots of approach-grafted pairs of tomato plants were subjected to combinations of differential treatments with base nutrient solution, base nutrient + 100 milliequivalents of NaCl per liter, base nutrient + 6 per cent sucrose, unaerated base nutrient, and distilled water. Intake of water, nitrate, postassium and sometimes other ions was determined under these conditions. It was found that addition of NaCl to the culture solution reduced the rate of intake of both water and the nutrient ions studied; that additions of sucrose reduced intake of water but had comparatively little effect on intake of NO3, Ca and K, while lack of aeration almost stopped nutrient intake, but had little effect upon water intake. Therefore, it is concluded that rate of water intake does not necessarily effect the rate of nutrient intake. Evidence is reported indicating that little if any translocation of salt occurred within these plants counter to the direction of water movement. It is suggested that salt injury to plants is the result of two fundamentally independent effects: (1) higher osmotic pressures in the substrate produce higher water tensions in the plant which influence physiological processes. (2) salt in contact with absorbing membrances of root cells and/or accumulated salt within the plant may produce deleterious effects on the protoplasm directly. [AS]

v.30:594-601, AMERICAN JOURNAL OF BOTANY

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