The present study was conducted at the experimental area of Horticulture Research Station at El-Kanater El-Khayria, Qalyubia Governorate, Egypt, during the two seasons 2019 and 2020, aiming to determine the best growth characters for three species of timber trees viz. Populus nigra, Paulownia hybrid T121 and Cedrela odorata irrigated under three irrigation rates 30, 45 and 60 % of the available soil moisture depletion (ASMD). The obtained results from the combined analysis of two seasons illustrate that the Populus nigra, Paulownia hybridT121and Cedrela odorata achieved the highest significant seedling height, stem diameter at 30% followed by 45% meanwhile 60% was the least. Also, Paulownia hybridT121 recorded the highest significant of seedling height, stem diameter and biomass fresh weight followed by Populus nigra meanwhile Cedrela odorata was the last one at different (ASMD). On the other hand, Populus nigra significantly gave the longest root length and Cedrela odorata was the intermediate, whilst Paulownia hybridT121 deduced the shortest one at 60 % (ASMD). Populus nigra significantly produced the highest values of dry biomass followed by Cedrela odorata meanwhile Paulownia hybridT121 achieved lowest values at the different (ASMD). Moreover, Cedrela odorata significantly exhibited the highest values of carbohydrates while Paulownia hybrid T121was the least and Populus nigra was in between in case of irrigating the seedlings at 45 and 60 % depilation. Paulownia hybrid T121 had taken more irrigation water applied and water consumption followed by Populus nigra while Cedrela odorata was the least at different (ASMD). As for that, Populus nigra seedlings recorded significantly highest water productivity and water use efficiency(WUE) followed by Cedrela odorata while Paulownia hybrid T121 recorded the least especially at 60 % depletion followed by 45 % and 30 % respectively.
It is worthily to notice also that, at different (ASMD) declared one liter of water applied produced 1.34, 1.00 and 1.29 gm biomass dry weight for Populus nigra, Paulownia hybrid T121 and Cedrela odorata respectively.
Therefore, it could be recommended from the herein results that, unadvisable a forestation Paulownia spp. under condition of Egypt in which it needs the greater amount of water used awing to less water productivity, less biomass dry weight causing reduce of WUE. So advises substitution anther types of object high economic recurrent such as Populus nigra or Cedrela odorata under or similar condition of this study.