عنوان مقاله [English]
Increasing green space and afforestation in arid and semi-arid regions has always been accompanied by water shortages. Species with lower water requirements have always been an executive policy in these areas. The aim of this study was to estimate the water requirement of Acer negundo and Pinus eldarica Medw as the main species that applied in green space of arid, outdoors, and greenhouses. For this study, soil field capacity, moisture limit, water requirement, and irrigation frequency of seedlings were determined. Then, the studied seedlings were subjected to two, four, and six water stress days after reaching the allowable point of moisture reduction. The results showed that the mean diameter and height of Afghan pine species at the beginning of the outdoor study period were 6.5 mm and 45.9 cm, and in the greenhouse were 5.6 mm and 46 cm, respectively. In addition, the average diameter and height of ash-leaved maple at the beginning of the experiment in the field were 7.7 mm and 97cm, and in the greenhouse were 9 mm and 80 cm, respectively. At the end of the period, these values were 10.2 and 111.8, 52 and 111 for outdoor space and 6.7 and 13, 52.3 and 104.1 for the greenhouse, respectively. For Afghan pine and ash-leaved maple, the fastest time to reach the allowable point of moisture reduction was 7 and 4 days in the greenhouse, 9, and 6 days in the field, respectively. The highest water consumption of Afghan pine in greenhouse and field on 19 to 20 June and on 1 to 2 May equal to 14.14 and 6.13% by volumetric water content; water content was 10.97 and 4.3% by weight water content. The highest moisture consumption of ash-leaved maple in greenhouses and arenas on 21 to 22 May and on 18 to 19 August equal to 11.58 and 4.03% by volumetric water content; the water content was 8.81% and 2.9% by weight water content. The results of this study showed that Afghan pine, as an evergreen species, has the highest tolerance to water shortage and has the lowest water requirement compared to ash-leaved maple. By knowing the number of water needs and irrigation cycle of species in the green space of metropolitan areas and economic savings in water consumption, we can try to develop new irrigation in these areas facing a water crisis.