|
Abstract
|
A pot experiment was conducted to examine whether the morphological and physiological
characteristics of some halophytes may be affected by salt stress. For this purpose, a factorial
experiment based on randomized complete block design was carried out with three replications.
The treatments were some halophytes (Salicornia europaea, Atriplex leucoclada, and Kochia
scoparia) and salinity stress levels [Electrical conductivity 0 (Hoagland’s solution), Hoagland’s
solution consisting of 100, 200, 300 and 500 mM NaCl]. Among the halophytes tested, Salicornia
europaea had significantly higher shoot and root of dry matters compared to the other halophytes in
all salt treatments. Salinity stress resulted in an increase in photosynthetic pigments up to 200 mM
and thereafter, it decreased in all of the studied plants. Photosynthetic pigments, ranked in a
descending order, were high in Kochia scoparia, Salicornia europaea, and Atriplex leucoclada. In
addition, salinity stress led to an enhancement in malondialdehyde (MDA) and H2O2. The tolerance
of Salicornia europaea under high salinity stress was associated with low MDA and H2O2 contents
as well as high contents of photosynthetic pigments. The shoot and root Na+ increased considerably
by augmenting the salinity levels in all halophytic plants; however, there was a significant difference
among halophytes at higher salinity levels. The shoot K+ decreased by increasing the salinity
levels, but K+ partitioning pattern varied among the halophytes. Under saline conditions, the shoot
and root Na+/K+ ratio of all halophytes grew. The highest and the lowest of Na+ were observed in
Salicornia europaea and Kochia scoparia, respectively. Thus, the Na+/K+ ratio could be considered
as an indicator of salt evaluation. Nitrogen, protein content, dry matter digestibility (DMD), and
metabolizable energy (ME) were high in Salicornia europaea plants in comparison to other plants
at 200–500 mM salinity levels; in contrast, acid detergent fiber (
|