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Nova Londrina, Brazil

Silva A.K.L.,Federal University of Para | Vasconcelos S.S.,Laboratorio Of Ecofisiologia Vegetal | de Carvalho C.J.R.,Laboratorio Of Ecofisiologia Vegetal | Cordeiro I.M.C.C.,Tramontina Belem S.A.
Plant and Soil | Year: 2011

Forest plantations and agroforestry systems with Schizolobium parahyba var. amazonicum have greatly expanded in the Brazilian Amazon, generally as an alternative for reforesting degraded areas. To our knowledge there are no reports of above- and below-ground production in these forest systems. We quantified litter and fine root production in 6-yr old Schizolobium-based plantation forests (monospecific: MON, mixture: MIX, and agroforestry system: AFS) and in ~25-yr old regrowth forest (REG) over 8-12 months. We used litter traps and ingrowth cores to quantify litter and fine root production, respectively. Annual litter production was significantly lower in Schizolobium-based plantations (mean ± standard error, MON = 5. 92 ± 0. 15, MIX = 6. 08 ± 0. 13, AFS = 6. 63 ± 0. 13 Mg ha-1 year-1) than in regrowth forest (8. 64 ± 0. 08 Mg ha-1 year-1). Schizolobium-based plantations showed significantly higher litter stock (MON = 7. 7 ± 1. 0, MIX = 7. 4 ± 0. 1 Mg ha-1) than REG (5. 9 ± 1. 3 Mg ha-1). Total fine root production over an 8-month period was significantly higher in Schizolobium-based plantations (MON = 3. 8 ± 0. 2, MIX = 3. 4 ± 0. 2, AFS = 2. 7 ± 0. 1 Mg ha-1) than in REG (1. 1 ± 0. 03 Mg ha-1). Six-yr old Schizolobium-based plantations and ~25-yr old regrowth forests showed comparable rates of litter + fine root production, suggesting that young forest plantations may be an interesting alternative to restore degraded areas due to early reestablishment of organic matter cycling under the studied conditions. © 2011 Springer Science+Business Media B.V.

Leite J.P.,Sao Paulo State University | Barbosa E.G.G.,Laboratorio Of Biotecnologia Vegetal | Marin S.R.R.,Laboratorio Of Biotecnologia Vegetal | Marinho J.P.,State University Londrina | And 16 more authors.
Genetics and Molecular Research | Year: 2014

Abscisic acid-responsive element binding protein (AREB1) is a basic domain/leucine zipper transcription factor that binds to the abscisic acid (ABA)-responsive element motif in the promoter region of ABA-inducible genes. Because AREB1 is not sufficient to direct the expression of downstream genes under non-stress conditions, an activated form of AREB1 (AREB1ΔQT) was created. Several reports claim that plants overexpressing AREB1 or AREB1ΔQT show improved drought tolerance. In our studies, soybean plants overexpressing AREB1ΔQT were characterized molecularly, and the phenotype and drought response of three lines were accessed under greenhouse conditions. Under conditions of water deficit, the transformed plants presented a higher survival rate (100%) than those of their isoline, cultivar BR 16 (40%). Moreover, the transformed plants displayed better water use efficiency and had a higher number of leaves than their isoline. Because the transgenic plants had higher stomatal conductance than its isoline under well-watered conditions, it was suggested that the enhanced drought response of AREB1ΔQT soybean plants might not be associated with altered transpiration rates mediated by ABA-dependent stomatal closure. However, it is possible that the smaller leaf area of the transgenic plants reduced their transpiration and water use, causing delayed stress onset. The difference in the degree of wilting and percentage of survival between the 35S-AREB1ΔQT and wildtype plants may also be related to the regulation of genes that protect against dehydration because metabolic impairment of photosynthesis, deduced by an increasing internal CO2 concentration, was not observed in the transgenic plants. © FUNPEC-RP.

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