Nashat M. Sabbouh
General Commission for Scientific Agricultural Research-
Faculty of Agriculture, Damascus University,
This study was carried out at Al- Nashabia Research Station in Damascus during 2007- 2008 evaluate the response of some rangeland species: five related to Chenopodiaceae (4 Atriplex sp., 1 Salsola sp.), two species to Poaceae (1 Agropyron, and 1 Oryzopsis), and the final species to Fabaceae (Onobrychis) at different levels (1, 5, 9, 13 dS.m-1 NaCl + CaCl2.2H2O) of salinity stress.
This research was divided into two experiments. The studied species were grown in the first experiment in plastic bags and put in the field, and in the second experiment the same species were grown directly in the field at the same time.
The two experiments were designed according to (split-plot design), in which the salt levels, in addition to control were applied in main plots, and the 8 investigated rangeland species were the sub-plots, with 4 replications each species at each level of salinity for the first experiment, and 3 replications for the second experiment. The salinity stress was conducted as soon as plants had reached the stage of complete germination, and till they had reached before flowering stage (for species related to Chenopodiaceae), and flowering stage (for species related to Poaceae and Fabaceae).
In general, the high salinity levels (9 and 13 dS.m-1) caused a significant reduction in most indicators studied on species related to Poaceae and Fabaceae, and some species related to Chenopodiaceae (Salsola vermiculata, and Atriplex canescens). On the other hand, low and medium salt concentration (5 and 9 dS.m-1) had a positive effect, so the studied indicators significantly increased compared with control and other treatments on some species related to Chenopodiaceae (Atriplex halimus², and Atriplex leucoclada). Relative and absolute water content in cells showed a significant increase with the increase of salt concentration in the growth medium, explaining how some species of Chenopodiaceae could tolerate salinity stress.
The investigated rangeland species producing higher green fodder such as Atriplex halimus², Atriplex leucoclada, and Oryzopsis millacea had given the biggest weight and length of roots comparing with other species.
The two types of A. halimus had given the biggest percentage of crude protein, crude fat, ash, and less percentage of crude fibres. As a result they were more important in the fodder value comparing with other Chenopodiaceae species, as well as Oryzopsis millacea had succeeded to give better fodder value comparing with Agropyron elongatum under salinity.
The increase of salt concentration in the growth medium didn’t affect percent crude protein, nitrogen-free extract, and crude fibber in the tissues of Onobrychis sativa and that means high fodder value, especially under salt-stress conditions.
After all, especially with the existence of genetic variation more efforts could be done for screening tolerant species from the other sensitive ones, and screening even under a certain species like A. halimus..