Abstract
This study was carried out in the greenhouse of the Federal University of Grande Dourados (UFGD), in the municipality of Dourados, state of Mato Grosso do Sul, Brazil, from April to May of 2015. The aim of this study was to assess the effect of different concentrations of abscisic acid (ABA) on the responses under water stress and recovery of Hymenaea courbaril L. seedlings after reirrigation. The following six treatments were assessed: 1) Irrigation with no ABA; 2) Irrigation + 10 µM ABA; 3) Irrigation + 100 µM ABA; 4) No irrigation nor ABA; 5) No irrigation + 10 µM ABA; and 6) No irrigation + 100 µM ABA. No irrigation treatment consisted on water suspension until the photosynthetic rate was close to zero. The plants were then irrigated daily to maintain 70% of the water holding capacity of the soil for a 12-days recovery period. ABA doses applied exogenously during the no irrigation period neither prevented the reduction of photosynthetic activity nor optimized the recovery of gas exchanges and carboxylation efficiency of Rubisco after water and seedling quality restoration. The concentration of 100 µM ABA promoted the degradation of chlorophylls independently of irrigation, which shows that high concentrations of ABA may cause a residual effect on this species. The seedlings exhibited normal metabolic recovery after about 12 days of reirrigation of the soil due to the characteristics of the species and not the tested treatments.
Highlights
Hymenaea courbaril L. (Fabaceae) is an arboreal species with a wide geographical distribution and can be found in phytogeographical areas of the Amazon, Caatinga, Cerrado, Atlantic Forest, and Pantanal (LIMA; PINTO, 2016)
The water deficit caused by irrigation without influenced some physiological parameters of the H. courbaril seedlings
After re-irrigation, seedlings recovered their photosynthetic metabolism in 12 days, demonstrating higher levels than those of irrigated seedlings without irrigation without (Figure 1A). These results suggest that the species possesses adaptation mechanisms after a 28-day water deficit period
Summary
Hymenaea courbaril L. (Fabaceae) is an arboreal species with a wide geographical distribution and can be found in phytogeographical areas of the Amazon, Caatinga, Cerrado, Atlantic Forest, and Pantanal (LIMA; PINTO, 2016). (Fabaceae) is an arboreal species with a wide geographical distribution and can be found in phytogeographical areas of the Amazon, Caatinga, Cerrado, Atlantic Forest, and Pantanal (LIMA; PINTO, 2016). This species has the ability to develop in different edaphoclimatic environments and is of forestry and environmental importance because of its potential as a carbon fixing and storage plant (CARVALHO, 2007). The growing concern about reforestation highlights the importance of studies on the tolerance or resistance of native species in both flooded and water deficit conditions, whereas the biome is characterized by seasonal rains and strong irradiance (LESSA et al, 2016). When exposed to water stress situations plants exhibit a wide range of molecular, cellular, physiological, and metabolic responses (FLOWERS, 2004) which can ensure their survival under such adverse conditions
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