What have we learned about the way leaf rust affects poplar growth?

GORTARI, FERMÍN; GRACIANO, CORINA; GUIAMET, JUAN JOSÉ

Bariloche

Conferencia; International Conference ?Adapting forests ecosystems and wood products to biotic and abiotic stress. Integrating tools, methods and disciplines to face global change; 2019

LIA Forestia

Leaf rust is a disease widespread in poplar plantations. Although there is variability between clones in the tolerance to rust, many of the materials used for timber plantations are susceptible in some degree. We used two clones with different susceptibility as models to know the way rust can affect poplar physiology and to quantify the effect of the disease in poplar growth. The main findings revel that rust infection alter leaf physiology since the early infection, through the reduction of gas exchange and hydraulic conductance. As infections develop, defoliation of the most infected leaves occur. It is important to highlight that leaf abscission takes place with high nutrient content in leaves because the fungi retain nutrients. Hence, the effect of rust is not only due to the loss of photosynthetic area and photosynthetic capacity, but also because rust severely affects nutrient recycling. In infected plants, a lower amount of nutrients are retranslocated to stems and roots during autumn. As a result, the vigor of the sprouting the following spring is lower in poplars that were infected the previous season, and this effect persists during the whole growing season. Repeatedly infections along the years reduce markedly poplar growth in volume and dry mass. Moreover, the basic density of the wood of infected plants was lower than the wood of healthy plants. Although the different susceptibility to rust of the clones evaluated, the same physiological processes are affected by the fungi, but in different magnitude. Finally, this research accentuates that a leaf disease alters not only the photosynthetic capacity of the plant, but also has an important effect in internal nutrient cycling.