The Kingdom of Saudi Arabia is one of the biggest Arab countries. Its size is 2 million squared km. So, its terrains are variable and numerous from one area to another. Each area is characterized by its special and different environmental plant systems. Most of these environments are suffering from high fragility degrees, due to its compositional nature, as a result they are highly vulnerable to impairment for the following reasons: decrease in rains, high temperatures, overgrazing and excessive distortion Due to the seriousness of this situation, the high authority for Riyadh development released a program for rehabilitation and cultivation of the vegetation and to maintain (preserve) its normal sites of spread. The authority also created many programs, studies and activities about this field. El-Thammama park is considered as one of the examples of this programs, which passes through two phases:
● Phase one: the cultivation of 99 000 seedlings of irrigated local plants, 60 000 seeds in irrigated sites and 140 000 seeds in non-irrigated sites, with different processing ways to discover the best ways to replant the local plants and vegetation.
● Phase two: the application and the development of the agricultural method with water harvesting and supplementary irrigation depending on the results of the first phase, and two different sites were chosen and cultivated with 4,000 seedlings of Talh.
The cultivation vegetation cover programs are based on the optimal selection of seeds. Seed collection is the first major step that involves the collection and classification of seeds and ensures their capacity for germination. We can depend on the cultivation of seedlings for their ability to adapt under field conditions, even after a series of processes that increase the success rate of field cultivation. After ascertaining the viability of seeds, seed treatment is done in several ways to break the surrounding envelope of the seed embryo to facilitate its germination under irrigated conditions.
The best time to begin planting seedlings is in April, preferably in May and June, when the soil is prepared for agriculture in terms of ventilation and control permeability and the ability of the soil to collect and retain water which increases the strength of root growth. In addition, to improve the organic properties by adding organic fertilizers and slow decomposition fertilizers and to increase the strength and quality of seedlings, which helps to alleviate stress damage under normal field conditions. To test and develop seedlings, two methods of sowing are used – direct mechanical seeding, and man growth. Insecticides and fungicides are usually used at the beginning of germination.
It is meant by hardening: exposure of plants to cycles of light, using cardboard boxes, the efficiency of the manual sowing method by the use of cardboard box show high survival and growth rates. It is an effective way of protecting seeds from climatic factors and mainly prevents sand crawling.