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INFLUENCE OF WATER AND SALT STRESS ON WATER RELATIONSHIPS AND CARBON DIOXIDE EXCHANGE OF TOP AND ROOTS IN BEANS
Author(s) -
JENSEN C. R.
Publication year - 1981
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1981.tb03199.x
Subject(s) - carbon dioxide , photosynthesis , turgor pressure , respiration , stomatal conductance , transpiration , chemistry , botany , bar (unit) , horticulture , osmotic pressure , biology , physics , organic chemistry , meteorology
SUMMARY When low‐salt plants, grown in nutrient solution, were exposed to osmotic potentials in the root medium (π s )* of minus 2.7 and minus 4.7 bar due to the addition of KNO 3 , osmotic adjustment occurred. The leaf osmotic potential (π 1 ,) decreased, leaf turgor potential (Ψ p ) and leaf water content ( W ) were maintained, no wilting took place, stomatal conductance (g) was partially regained and net photosynthesis was only moderately depressed. When low‐salt plants were exposed to π s of minus 2.7 and minus 4.7 bar due to the addition of PEG 1500, no adjustment to water stress was observed. Ψ p decreased, the leaves became dehydrated and a high percentage wilted. Stomatal conductance, net photosynthesis, top dark respiration and root respiration were depressed. NO 3 ‐uptake ceased completely at minus 4.7 bar. When low‐salt plants were exposed to π s of minus 4.7 bar, due to both PEG (minus 2 bar) and KNO 3 (minus 2 bar), osmotic adjustment took place; π 1 decreased, Ψ p , W, g , net photosynthesis, top dark respiration and root respiration recovered to some extent, but the proportion of wilted leaves was high. When medium‐ and high‐salt plants, osmotically adjusted to π s of minus 2.7 and minus 4.7 bar due to KNO 3 were exposed to water stress due to PEG (minus 2 and minus 4 bar), (Ψ p and W were maintained, none or few leaves wilted and g was depressed less than in low‐salt plants. These responses are attributed to influence of pre‐osmotic adjustment on turgor maintenance and hydration of the plant. It is concluded that osmotic adjustment by inorganic solute uptake, before or during exposure to water and salt stress, can reduce the severe effects of low water potentials in the root medium.