Morphometric and physiological responses to drought stress on pot grown cuttings of poplar clones with "greater environmental sustainability

The Italian poplar cultivation has recently turned its attention to 'MSA' clones with 'Greater Environmental Sustainability', characterized by resistance to the principal biotic stresses, requiring less pesticides. To date, there is limited information on the drought tolerance of these clones. This work aimed to determine the degree of tolerance/susceptibility to drought in poplar clones with 'Greater Environmental Sustainability' than the reference clone 'I-214'. Firstly, a preliminary experiment with three different clones under drought stress showed a statistically significant alteration on morphometric and physiological parameters than under normal conditions. The physiological and biochemical indices related to drought tolerance of 'Neva' clone were improved, resulting in greater tolerance than 'I-214' and 'San Martino' clones. A second experiment was conducted by expanding the population of clones considered. The results showed that the relative water content was not significantly different among the control treatments and the drought-stressed ones. In particular, the analysis showed a greater degree of tolerance to the water stress of the 'Neva' clone and the 'Tucano' clone. On the contrary, the 'Lena' and 'San Martino' clones were more susceptible to water deficiency stress. The water stress significantly decreased photosystem II performance, the stomatal conductance, and transpiration compared to the control one. Future analyses will be focused on the characterization of clones and genetic improvement for drought tolerance.