Impact of drought on the growth of seedlings of Pyrus pyraster and Tilia cordata

Soil drought negatively affects growth, survival, and biodiversity of woody plants in urban areas. Long-living woody plants have different strategies to cope with drought stress. Knowledge of the species-specific adaptive responses of woody plants will provide opportunities to produce ornamental woody plants with a higher tolerance to water scarcity. This research aimed to assess the impact of drought on woody plants in the juvenile growth stage and the identification of species-specific reactions of woody plants to low water content in the substrate. The studied species were Tilia cordata Mill. and Pyrus pyraster (L.) Burgsd. from the native habitats in Slovakia. Both taxa can be used for ornamental purposes in urban greenery. The plants used in the experiment were grown from seeds. The seedlings were placed in pots at the phenological growth stage “cotyledons completely unfolded. The potted seedlings were grown under controlled environmental conditions in a growth chamber and maintained under a regulated water regime for 105 days. The root parameters, root length, volume, surface, and volume of the fine and coarse root fractions, were measured by the analytical software WinRhizo. The dry weight of aboveground organs, the leaf water content (LWC), leaf area (LA), and specific leaf area (SLA) were also measured. According to the obtained results, T. cordata showed better growth of both aboveground and belowground biomass than P. pyraster. However, during drought periods, a significant reduction (50%) of the dry matter in plant organs was observed in Tilia. Both species used different mechanisms of adaptation to drought, but maintained a stable water content in the leaves. In drought conditions, P. pyraster preferably invested in dry matter of the roots. T. cordata allocated more dry matter to aboveground organs, created thicker leaves, and increased the volume of the fine root fraction.