Inyecciones de glucosa en Jacaranda mimosifolia D. Don en áreas urbanas de Texcoco de Mora

Abstract

Los árboles de jacaranda son comunes en áreas urbanas del valle de México y se desarrollan frecuentemente bajo condiciones de estrés nutricional o hídrico, lo que restringe el crecimiento del arbolado. El suministro de carbohidratos a través del sistema vascular recientemente se ha recomendado como una opción para mejorar el crecimiento y vitalidad. Por lo anterior, el objetivo del trabajo fue evaluar el efecto de la glucosa sobre crecimiento y vitalidad de árboles de Jacaranda mimosifolia inyectada al tronco en cuatro concentraciones: 0 (testigo), 30, 55 y 80 g L-1 Se midieron incrementos en diámetro (cm) y altura (m), se monitoreó la condición de copa y producción de follaje y además se evaluó el contenido de carbohidratos en brotes, troncos y raíces, así como la fluorescencia de la clorofila (Fv/Fm). Se encontraron diferencias significativas (P≤0.05) en el incremento en diámetro y altura con la aplicación de 80 g L-1 de glucosa. La condición de copa mostró valores significativamente más altos en densidad y bajos en transparencia, así como una buena producción de follaje, con la concentración más alta del carbohidrato (80 g L-1). Su contenido presentó diferencias significativas (P≤0.05) en tronco, no así en brotes, raíces, ni en valores de fluorescencia de la clorofila. Las inyecciones de glucosa al tronco tienen un efecto significativo en el crecimiento de árboles de esta especie y afectan en menor medida la vitalidad del arbolado.

Tree Health Condition in Urban Green Areas Assessed through Crown Indicators and Vegetation Indices

“…Cdn and Ctr can vary by species, age, genotype and evaluation periods. Despite this, at present, these variables are widely used as useful indicators in the evaluation of tree crown condition in both natural and urban environments [6,22]. Regarding Cdie, it presented low frequency within the trees in the 21 UGAs evaluated (Figure 5C).…”

“…On the other hand, the correlations between Fv/Fm and both Cdn and Ctr (Figure 6) indicate a reference to the health condition of the trees, since it is known that the presence of sparse crowns or those with high percentages of transparency are indicative of stress, which can be evaluated through Fv/Fm [22,50]. Fv/Fm is widely used in crop analysis; however, its use has rapidly spread to other natural and non-natural environments, so it is also used in urban tree stress assessment [32,49].…”

“…Fv/Fm is widely used in crop analysis; however, its use has rapidly spread to other natural and non-natural environments, so it is also used in urban tree stress assessment [32,49]. For example, some studies have detected stress in tree plant species through Fv/Fm under various cultural practices within UGAs, which include management and maintenance activities, particularly crown pruning or transplanting of urban trees [6,22,49]. Finally, NDVI and BNDVI were found to correlate with Cdn and Ctr, this given that they use a similar mathematical relationship [48]; however, the crown variables are better related to NDVI.…”

“…Chlorophyll fluorescence (Fv/Fm) was assessed in the sampled tree species as an indirect measure of the overall tree health through their physiological stress condition [49]. A portable Pocket PEA fluorimeter (Hansatech Instruments Ltd., King's Lynn, UK) was used, with a detection parameter of 1 s and light emission at a wavelength of 650 nm with an intensity of 3500 µmol m −2 s −1 [22]. The measurements were made by adapting to the dark and using the fluorimeter clips for 10 min on a total of 5 leaves chosen at random around each tree's crown [50].…”

“…On the other hand, there are methods to evaluate physiological processes to quantify the response of trees to stress, one of them being chlorophyll fluorescence (Fv/Fm). This index indicates the photosynthetic efficiency of the system of the leaves; thus, a lower efficiency is related to a lower health condition of the vegetation [21,22].…”