Desiccation studies on mahogany (Swietenia macrophylla) seeds

Studies of desiccation effect on mahogany seeds were conducted to determine the best condition to reduce seed moisture content without affecting its viability. Four types of desiccation methods, namely, ambient temperature of 28 °C (in incubator), cold room of 21 °C (in laboratory), circulated air oven at 35 °C and silica gel (in desiccator at 25 °C) were tested on seeds with and without testa. All four desiccation treatments maintained high germination between 70-78% for seeds with testa. Ambient and cold conditioned seeds without testa resulted in 55-70% germination. Overall results showed that a gradual reduction of moisture content to the lowest safe level while maintaining high viability can be achieved using ambient and cold conditioned desiccation techniques. Oven and silica gel desiccation methods increased respiration rate and cellular leachate conductivity, especially for seeds without testa. Light microscopy showed that cells of seeds without testa desiccated using oven and silica gel had damaged cell walls and cytoplasms. These injuries did not occur in cells of seeds with testa. It was concluded that mahogany seeds with testa can be stored for a short-term period if the moisture content is reduced gradually to 2-9% using environmental condition of 21-28 °C.