Physiological and biochemical performance of Pouteria ramiflora (Mart.) Radlk. seeds harvested at different maturation stages and subjected to drying

This study aimed to evaluate alterations in the physiological and biochemical performance of Pouteria ramiflora (Mart.) Radlk. seeds at different maturation stages when subjected to drying. The seeds were harvested at two maturation stages (unripe and ripe). A sample of seeds at each maturation stage was not subjected to drying (control), and another sample was subjected to drying in a convection oven at 35°C until the seeds reached water content levels of 20 and 12% wet basis (w.b.). The drying of seeds up to 12% bu. negatively affected the physiological quality and vigor of the seeds, particularly in the unripe seeds. There was no detectable activity of catalase and peroxidase isoenzymes, and heat-resistant proteins were not observed on denaturing polyacrylamide gels. The α-amylase enzyme was most active in mature and moist seeds and showed the negative effect of drying, particularly with respect to unripe seeds. A greater intensity of esterase isoenzyme bands was detected in unripe seeds (regardless of water content) with little reduction of activity as the water content of mature seeds decreased. It can be concluded that the P. ramiflora (Mart.) Radlk. seeds show physiological and biochemical alterations when subjected to drying, they are intolerant to desiccation.   Key words: Forest species, physiological maturity, desiccation tolerance, isoenzymes.