Effect of water deficit on water status and growth of five tropical species used in urban forestry

Due to the urban environment urban trees must deal with drier and hotter than in rural areas. Knowing the water consumption of each species and the indicators of water deficit is useful to decide the frequency and volume of irrigation and to select species according to the microclimate of the location. To determine approximately the irrigation frequency and to identify physiological variables that indicate water stress, it was carried out an experiment in which five tropical species (Citharexylum montanum M., Citharexylum sulcatum M., Caesalpinia spinosa K., Inga edulis M. and Retrophyllum rospigliosii P.) were subjected to water deficit. After a month of planting, eight trees per species were subjected to four treatments: control treatment (volumetric water content higher than 45% (TC)), the volumetric water content of 20% (VM20), fifteen and thirty days after the soil had reached VM20 (T15 and T30, respectively). In trees with similar height, it was found that the descending order of water consumption was I. edulis, C. montanum, C. spinosa, C. sulcatum, R. rospigliosii and that the best indicator of water deficit was the stem water potential. In general, volumetric moisture of soil of 20% was a suitable threshold to decide when irrigating regardless of the species. Deeming the effect of the treatments on the growth of the assessed species, T30 diminished severely the growth by 50% in comparison to the control, except for C. sulcatum in which there were no significant differences.