International Symposium on
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The Effect of Petroleum Mulching on Seed Germination
of Desert Plants in Iran

Vahid Jafarian

Natural Resource Management & Combating Desertification Specialist
Forest, Range, and Watershed Organization, Iran



More than 80% of Iran’s territory is located in arid and semiarid region.  The majority of these regions, about 5 million hectares, are subject to wind erosion and its destructive effects, especially the moving sand dunes, which are the most critical and difficult areas for managing.

A study using petroleum mulch was conducted in order to look at its effects on stabilizing shifting sand dunes and preserving the soil moisture, which in turn could increase seed germination, help in establishment of new seedlings thus increasing natural plant and ground cover. The effects of petroleum mulching on seed germination and establishment of new seedlings for different desert plants species was the special focus of this study. Changes of soil temperature as a result of mulching are one of the most influential factors on seed germination.  Due to its dark color, petroleum mulch can absorb sun heat and increase the temperature of soil surface layer effecting seed germination.

The study area includes two distinct desert lands of Iran: (i) Pivashk a coastal sandy desert located in Jask city in Hormozgan province and; (ii) Booing Jazmoorian an inland desert, located in Kahnoj city in Kerman Province.   Petroleum mulching (first factor) was applied on 4 plants species (second factor) (Haloxylon persicum , Calligonum polygonoides, Prosopis julifera and Prosopis cineraria.) in the Booing Jazmoorian area and on 3 plant species (Calotropis procera, Prosopis julifera and Prosopis cineraria) in the Pivashk area.  Its effects on seed germination were investigated and compared to the control (no mulching).  The study was conducted in two replications.  The assessment of the amount of seed germination was conducted 3 times during April, May, and June of 2005 to be able to determine also the time effect of the treatments.  The temperatures were measured once every 15 days for air, soil surface, and to a depth of 5 cm at different hours of the day in both mulched and controlled treatments in Booing Jazmoorian area.

The results showed that in Pivashk region there was a significant difference in seed germination percentage between mulched and non mulched areas, 7.2 % and 0.33%, respectively.  There were also significant differences (P > 0.01) in seed germination percentage among different plant species with the Calatropis procera being the highest, 8.25% and in Prosopis cineraria the lowest (0.0 %).  In Booing Jazmoorian region there was also a significant difference in seed germination percentage between mulched and non mulched areas.   In this region the seed germination percentage of mulched Haloxylon persicum was the highest 71.8%, while for the non mulched was 27%. The seed germination percentage of Prosopis cineraria was the lowest, with a mean seed germination percentage of 2.7% for the mulched treatments as compared to only 0.7% for the control.

The results of temperature monitoring on the soil surface and at 5 cm depth in Booing Jazmoorian region revealed differences between the soil mulched and control.

Keywords: Desert, Sand dune, Petroleum mulch, Seed germination, Haloxylon persicum. Calligonum polygonoides. Calotropis procera , Prosopis julifera . Prosopis cineraria