Adaptation and morpho-physiology of three Populus deltoides Marsh. x P-nigra L. clones after preconditioning to prolonged waterlogging

The implementation of a management-protection program, using suitable cultivation practices, contributes to rehabilitating marginal areas prone to prolonged waterlogging and preserving biodiversity. Three hybrid poplar clones ('I-488', 'Rimini' and 'D-64') were tested to assess their degree of tolerance to waterlogging by imposing four water regimes over a 1 year period: control (C), non-preconditioned (NPr), and two levels of flood preconditioning (Pr-10 and Pr-20). During the 2nd year, waterlogging (1.9 +/- A 0.7 mg/l O-2) was imposed on plants from NPr, Pr-10 and Pr-20 treatments for 60 days followed by drainage. Survival rate, dry mass production, net photosynthesis and relative damage to membrane structural integrity were evaluated. The treatment response varied among clones and levels of preconditioning. Less pronounced damage to 'I-488' clones in comparison to those of 'Rimini' and 'D-64' indicates its superior tolerance to waterlogging. Preconditioning treatments (Pr-20) and, to a lesser extent (Pr-10), significantly improved the ability of the clones to tolerate flooding, suggesting that the application of a Pr-20 preconditioning treatment in the nursery before outplanting would give hybrid poplar clones the morpho-physiological advantages necessary to counteract the arduous conditions on inundated sites.