The objective of this study was to investigate the physiological and biochemical alterations in tamboril-da-mata (Platymiscium pubescens) osmoconditioned seeds. Embryonic axis growth, germination, cell wall changes, carbohydrate and protein content and á-galactosidase activity were analyzed. Seed water content for control seeds was found to increase continuously throughout 96 hours of imbibition, while those maintained in the PEG solutions stabilized at 48 hours. Germination occurred only in seeds maintained in water, reaching 30% in 120 hours. The seeds maintained in -0.4 MPa PEG solution for 120 hours showed 66% of germination when transferred to water, and had the greatest potential. Fresh matter and length increased significantly during the 120 hour period in PEG solution (-0.4 MPa/120 hours), while dry matter showed no significant increment. Arabinose and xilose contents in water washed-membranes decreased significantly during osmopriming. Galactose was not detected until 120 hours. Arabinose had the largest concentration. The a-galactosidase activity showed significant activity during the 120 hour period. Ramnose, arabinose and xilose contents changed significantly in the pectic fraction, while ramnose was the only one in the hemicellulose fraction that showed significant change. Glucose contents changed significantly during the osmopriming. Staquiose and raffinose contents showed no significant change, while sucrose content was reduced significantly though maintained higher than the other oligossacharides during the entire period. Protein contents decreased significantly after 120 hours of osmopriming. It was concluded that priming caused seed germination by reducing sugar deposition in the cellular wall.
Germination; Platymiscium pubescens; carbohydrate; protein; cellular wall
