ABSTRACT
The intense environmental degradation in tropical regions suitable for agriculture has decreased native forest populations of plants with important fruits and medicinal properties. Alibertia edulis is a native tree from the Brazilian Cerrado. Knowledge about the effects of drying and storage on the physiological behavior of its seeds may aid in its sustainable exploitation and conservation. The goal of the present study was to determine which fruit ripening stage results in A. edulis seeds with higher tolerance to desiccation, and to investigate the effectiveness of polyethylene glycol (PEG) induced osmotic stress in combination with abscisic acid (ABA) in increasing seed desiccation tolerance during storage. Seeds were dried in activated silica gel (fast) or under ambient conditions (slow). Seeds originating from mid-ripe or fully ripe fruits exhibited better physiological performance than those obtained from green fruits. Slow drying resulted in seeds with high physiological potential. Seeds may be stored for up to 180 days without losing viability when treated with -0.73 MPa PEG without ABA.
Subject(s)
Desiccation/methods , Germination/physiology , Rubiaceae/physiology , Seeds/physiology , Abscisic Acid/pharmacology , Adaptation, Physiological , Rubiaceae/drug effects , Rubiaceae/growth & development , Seeds/drug effects , Seeds/growth & development , Stress, PhysiologicalABSTRACT
The aim of this study was to evaluate gas exchange, efficiency of the photosynthetic apparatus, and antioxidant activity in Copaifera langsdorffii Desf. The seedlings were cultivated under different conditions of water availability, in order to improve the utilization efficiency of available water resources. The seedlings were cultivated in four different water retention capacities (WRC- 25%, 50%, 75%, and 100%), and evaluated at four different time (T- 30, 60, 90, and 120 days). During the experimental period, seedlings presented the highest values for carboxylation efficiency of Rubisco (A/Ci), intrinsic water use efficiency (IWUE = A/gs), chlorophyll index, and stomatal opening, when grown in the substrate with 75% WRC, but the stomatal index (SI) was less the 25% WRC. The efficiency of photosystem II was not significantly altered by the treatments. Comparison between the extreme treatments in terms of water availability, represented by 25% and 100% WRC, represent stress conditions for the species. Water availability causes a high activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) in the plant.
Subject(s)
Antioxidants/metabolism , Fabaceae/metabolism , Seedlings/metabolism , Water/metabolism , Carbon Dioxide/metabolism , Chlorophyll/metabolism , Fabaceae/classification , Fabaceae/physiology , Plant Stomata/metabolism , Random Allocation , Time FactorsABSTRACT
ABSTRACT The aim of this study was to evaluate gas exchange, efficiency of the photosynthetic apparatus, and antioxidant activity in Copaifera langsdorffii Desf. The seedlings were cultivated under different conditions of water availability, in order to improve the utilization efficiency of available water resources. The seedlings were cultivated in four different water retention capacities (WRC- 25%, 50%, 75%, and 100%), and evaluated at four different time (T- 30, 60, 90, and 120 days). During the experimental period, seedlings presented the highest values for carboxylation efficiency of Rubisco (A/Ci), intrinsic water use efficiency (IWUE = A/gs), chlorophyll index, and stomatal opening, when grown in the substrate with 75% WRC, but the stomatal index (SI) was less the 25% WRC. The efficiency of photosystem II was not significantly altered by the treatments. Comparison between the extreme treatments in terms of water availability, represented by 25% and 100% WRC, represent stress conditions for the species. Water availability causes a high activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) in the plant.
