Interaction effects of water supply and artificial defoliation in autumn on growth, biomass and nutrient accumulation in Populus deltoides

GORTARI F; MARTÍNEZ ALONSO, S.M.; GUIAMET J.J; GRACIANO C.

NEW FORESTS

SPRINGER

Año: 2021 vol. 52 p. 1037 - 1054

0169-4286

AbstractPoplar productivity is negatively affected by excess or deficit of water availability and byinsect and pathogens that cause defoliation. Some foliar diseases, like leaf rust, producedefoliation at the end of the summer. The interaction between water stress and defoliationis poorly understood. Hence, the aim of this work was to test if defoliation would have astronger effect on growth, biomass and nutrient accumulation in well-watered plants thanin water-stressed plants. The experiment started with 36 Populus deltoides unrooted cuttings, which grew outdoors in pots throughout a complete growing season. Water stresses(flooding and drought) were imposed from early summer when cuttings were established.Defoliation (50%) was applied at the end of summer when plants were acclimated to waterstress. We analyzed photosynthetic parameters in response to water stress and biomass,nitrogen and phosphorus accumulation and partitioning at the end of the first growing season. Artificial defoliation produced similar reduction of plant height and aboveground biomass in the three water conditions; but in well-watered plants caused a strong decrease inbelowground accumulation. Defoliation increased nitrogen resorption from leaves beforeabscission only in plants under drought, but it had no effect in nutrient resorption in wellwater and flooded plants. Defoliation decreased nitrogen and phosphorus storage in everywater condition. The results are relevant to manage poplars in environments with multiplestresses, because defoliation at the end of the growing season and water stress have relevant impact on plant growth, nutrient storage capacity and on the internal distribution ofnutrients.