EFFECTS SOIL COVERING AND CONTROLLED WATER TABLE ON DATE PALM GROWTH AND THE ROOT ZONE SALT BALANCE IN SOUTHWEST OF IRAN

摘要

Drought, shallow saline water table and subsequent salinisation are the major problems in arid and semi arid in Iran. The establishment period of date palm plant is highly sensitive to these problems and need special management program. Lysimeter experiments were conducted to evaluate the influences of shallow saline water table on the salt balance of root zone and date palm growth. These experiments were carried out in three replicated split–plot design including 3 levels groundwater salinity (main plot; S1= <4, S2= 8 and S3=12 dS/m); two levels soil surface cover (sub plot: M1= no mulch and M2= date palm leaves mulch) and two water table depths (D1=60 and D2=90 cm). The results showed that mulching help to increase salt leaching and decreased soil EC with water table at 60 cm depth. The maximum decrease was 2.55 dS/m in treatment D1S1M2. The EC of root zone soil increased in treatments without mulch, the maximum being 6.31 dS/m in treatment D1S3M1. The soil EC increased in all treatments with controlled water table at 90 cm depth. The maximum and minimum change of soil EC was 6.5 and 2.64 dS/m in treatments D2S3M1 and D1S1M2, respectively. The ANOVA analyses indicated that mulch has a significant effect on salt change rate of the root zone at 1% level. However, levels of salinity did not have a significant difference. Similar results were obtained for both depths of the water table. The survival rate of plants was 100% in all of treatments. The date palm plants tolerated soil salinity till 14.29 dS/m. Mulch improved the growth of date palm plant. With controlled water table at 60 cm, the new leaf and leaflet numbers were 4.33 and 117.67 in treatment D1S3M2. These indexes were 4 and 120.33 for.