Efeito responsivo de mudas de paricá ao estresse hídrico

Abstract

The present study objective was identifying mechanisms of response to water deficit of paricá seedlings. The experiment was conducted in a greenhouse, in 8-liter pots, with substrate consisting of soil (dystrophic RedYellow Latosol), in randomized block design, with five different irrigations based on the evapotranspiration of the plants (20, 40, 60, 80 and 100%), with six replications. The plants were irrigated daily, with a water volume corresponding to 100% of the evapotranspired water, and, at 90 days after germination, subjected to ten days of water deficit, after that irrigated during ten days with the different percentages of evapotranspiration, then evaluated. The following variables were measured: number of leaves (NL), plant height (PH), stem diameter (SD), total biomass (TB), total daily transpiration (TDT), total chlorophyll (TC), carotenoids (CAR), root mass ratio (RMR), leaf mass ratio (LMR) stem mass ratio (SMR). Concluded that paricá seedlings response to water deficit with slowing down of dehydration, with reduction of content of carotenoids and increase in root volume. As a consequence of water stress, they reduce the number of leaves, stem diameter, plant height, and, of course, total biomass, aiming at maintaining the internal water, indicating low ability to tolerate stress.

Water requirement and growth indicators of forest tree species seedlings produced with automated irrigation management

“…This ratio is used to assess the quality of forest seedlings, because, in addition to reflecting the accumulation of reserves, it ensures greater resistance and better fixation in the soil [ 27 ]. The occurrence of water deficit in the substrates tends to limit the growth of tree seedlings in terms of diameter and height and modify the ideal H/D ratio for a given species [ 28 ]. However, the variations in the H/D ratio observed in this study were not enough to provide signs of etiolation in the seedlings.…”

Response of Schizolobium parahyba seedlings to water stress

“…amazonicum (paricá) and other species, but there are no studies to confirm this. Duarte et al (2016) reported that S. parahyba var. amazonicum plants when submitted to water deficit, with subsequent water replenishment, showed reduction in the number of leaves, stem diameter, plant height, and, of course, total biomass, as response to maintain the internal water, indicating low ability to tolerate stress.…”

“…The seeds came from the Aimex Laboratory of Seeds and Seedlings of the Amazon Forest Species. Dormancy break procedure was applied to the seeds, according to the methodology proposed by Duarte et al (2016). Three seeds were sown in each pot and thinning was carried out 30 days after emergence (DAE).…”

“…The plants were irrigated daily with only the amount of water corresponding to the maximum daily evapotranspiration capacity. Subsequently, at 90 DAE, the plants were subjected to ten days of water deficit, being irrigated with 20, 40, 60, 80 and 100% of evapotranspiration, for another ten days, similar to Duarte et al (2016).…”

“…The growth variables (number of leaves -NL, plant height -PH, stem diameter -SD, total biomass -TB) and physiological variables (total daily transpiration -TDT, carotenoids -CAR, total chlorophyll -TC, relative water content -RWC) were analyzed according to Duarte et al (2016). Data were subjected to analysis of variance and when significant we conducted the regression analysis (p < 0.05), using SISVAR statistical software (Ferreira, 2014).…”