Research on determination of seed collection time, seed quality test, seed preservation and techniques to produce seedlings of De xanh (Lithocarpus pseudosundaicus (Hickel et A.Camus) Camus)

Abstract

The study was conducted to determine the time of seed collection, seed quality test and techniques to produce seedlings of De xanh (Lithocarpus pseudosundaicus) from seeds. The results showed that Lithocarpus pseudosundaicus flowers from April to May, fruits ripen from October to November. One should collect seeds when fruit shells change the colour from green to brown or dark brown. The average weight of 1,000 ripe seeds is 5.7kg, the purity of seeds is about 90.4%,
and the germination percentage is between 84.8% to 85.0%. After collection, seeds should be sown immediately or to be stored in moist sand at a ratio of 2 sand parts: 1 seed part in volume or kept in fridge at 8oC to 9oC, which can maintain the germination percentage of 77.1 - 79.9% after 3 months of preservation. The germination ratio drops strongly to below 50% after 6 - 9 months of storing. The best treatment is to soak seeds in water at an initial temperature of 75oC in 8 hours, then picking seeds out to clean and store in moist sand. After 20 days, seeds begin to germinate. The germination percentage is 84.67%. During the first 3 months after planting, the formula of 75% of light shading is the best for seedling growth; 50% of light shading is
the best for seedling growth at the stage of 6 - 9 months old and this rate should decrease to 25% when seedlings reach 12 months old. The most suitable potting mix formula for seedling production of Lithocarpus pseudosundaicus is 88% of soil + 10% of muck and 2% of super phosphate.