The Diurnal Pattern of Gas Exchange in P. euphratica

The measurements on photosynthesis and related parameters indicated that CO₂ compensation point and saturation point increased,while Rubisco activity decreased with the increase of salt stress for two genotypes Under high salt treatment,the net photosynthesis of P. euphratica recovered from salt stress when soil salt content was about 0.7% NaCl,while that of hybrid only recovered when soil salt content was less than 0.2% NaCl and was unable to when soil salt content was about 0.5% NaCl;chlorophyll a contents and Chl a/b ratio increased,while chlorophyll b and carotenoid contents decreased with increasing salt levels Fluorescence patterns confirmed that reduction of photosynthesis under high salt treatment was not due to damage of photosynthetic apparatus but due to inhibition of the dark reaction.