English abstract
Water salinity is one of the major issues in Gulf countries, including Oman. Two experiments were conducted to observe the ability of specific soil amendments to reduce the effects of high salinity on two common seasonal flowers; Catharanthus
roseus (vinca) and Tagetes erecta (marigold). The soil amendments were peat moss, which is available in local markets imported from Netherlands and a soluble silica product imported from Australia. Two salinity levels; tap water and high salinity water
from a farm located in Al-Batinah were used in experiment #1, and three salinity levels; tap water, moderate salinity (3 dS/m) and high salinity water (5 dS/m) were prepared in the lab for experiment #2. Both experiments were conducted for 5-6 weeks' period under growth chamber (experiment #1) and glass house conditions (experiment #2).
Results showed that in both experiments, the addition of soluble silica raised the soil silica level and decreased K+ in the soil.Peat moss also increased soil silica levels, but did not increase the organic matter level when it was measured in experiment #2. In both experiments, the addition of peat moss also resulted in decreasing pH and was statistically significant in both experiments. In addition, in both experiments, peat moss and silica treatments showed ability to decrease levels of EC and Na+ compared to the control treatment but they were only significantly different in experiment #1. Plant growth and biomass also was significantly increased in experiment #2 for peat moss and silica but it was not in experiment #1 for any of the soil amendments used. Chlorophyll content was statistically increased by the silica treatments when it was measured in
experiment #1. In summary, neither of the amendments tested had a negative effect on the plants, and both show possible benefits, especially under saline conditions. The peat moss had the effect of adding organic matter as well as decreasing pH. Under growth chamber and glass house conditions, rates for both amendments of about 11% and 20% by total volume were applied, and lower rates would likely be used under field conditions. Further testing under field conditions would also provide valuable information about whether these amendments benefit plants that are under additional stress such as insects or diseases pressure in addition to soil salinity.
