An assessment of water requirement and investigation of different irrigation levels on growth parameters of eldar pine (Pinus eldarica Medw) seedlings (case study: Tehran)

This study was carried out to evaluate the effects of different irrigation levels on some morpho-physiological properties of pine (Pinus eldarica Medw.) in Tehran green areas in 2015 and 2016. For this purpose, water requirements of pine in the studied area was estimated using the method recommended by FAO for drip irrigation system and WUCOILSIII method, then the effects of four levels of irrigation (50, 75, 100 and 125% water requirements) on some growth properties of pine species during the growth season were investigated in a split plot experiment in time based on randomized complete block design. The results showed that the amount of rainfall in April (in the first year) and also in April and May (in the second year) were more than the estimated amount of pine water need. The highest amounts of water requirement in both years were estimated in June (204.6 and 246.45 liters per month), wherase the lowest ones in the first and second years (139.5 and 117 liters per month) were determined in May and October, respectively. The treatment of 50% water requirement significantly decreased the branch length, branch diameter, height, tree crown diameter and pine crowns and increased the percentage of leaf and branch dry matters and proline in comparison with the control treatment. Leaf abundance per tree and leaf succulence were not affected by irrigation treatment. In general, the results of this study showed that meanwhile maintaining the important indics of green erea, water consumption for Tehran pine trees in the studied area could be reduced to 50% of the water requirement in the first months of growing season and to 75% of that in the others months of year