[Changes in the growth and photosynthesis of cotton seedlings under progressive drought after saltwater irrigation].

Pot grown cotton plants were watered with saltwater (NaCl solutions of different concentrations), followed by a duration of progressive drought stress. The changes in plantlet growth, photosynthetic rate, chlorophyll fluorescence were measured, and the water status of the plantlets, such as relative water content, water potential, osmotic potential, the Na+ and K+ contents in leaves during drought were measured and analyzed, in order to get an insight into the role of Na+ played in the adaptation of cotton to drought stress. The results showed that the growth of the plantlets was significantly inhibited, the net photosynthetic rates were remarkably lowered by the drought stress, but the plant height, biomass, net photosynthetic rate and Fv/Fm values in the cotton plants watered with 25-100 mmol x L(-1) x NaCl solution under drought stress were significantly higher than those watered with water under the same intensity of drought stress.

[Responses of Atriplex triangularis root permeability and reflection coefficient to salt stress].

Taking hydroponically cultured arrow-leaf saltbush (Atriplex triangularis) seedlings as test materials, and using electrical conductivity detector, atomic spectroscopy, and pressure bomb, this paper studied the effects of salt stress on the seedlings root membrane permeability, ion uptake, and reflection coefficient, and analyzed the salt-resistance characteristics and related mechanisms of A. triangularis. The results showed that with increasing salt stress, the root membrane permeability increased, but the reflection coefficient decreased.

[Self-regulation of xylem pressure in barley roots under salt stress].

Xylem pressure in young barley roots, measured in vivo with a xylem pressure probe, showed constant, irregular fluctuations both under altered or unchanged environmental conditions. When mild salt stress was applied or when the stress was eliminated, xylem pressure in barley roots exhibited intense self-regulation or relaxation, leading to a consequence that the difference of xylem pressure before and after the salt stress was greatly narrowed and the barley plants could maintain a relatively stable xylem pressure. The process of regulation or relaxation of xylem pressure in barley roots lasted about one hour or more before a relatively stable state was achieved.