多胚性蒲桃种子的脱水敏感性

Desiccation Sensitivity of Polyembryonic Syzygium jambos Seeds

摘要: 种子是一种极为重要的种质资源，若不查明其脱水耐性，则难以科学保存。为了确定多胚性蒲桃种子是否属于脱水敏感性种子及其适宜的萌发温度，以便更好地保存和利用其种子，本研究以成熟的蒲桃种子为实验材料，进行了干燥脱水与萌发实验。结果表明：成熟的蒲桃种子初始含水量较高(50.15%)，在30℃和30/20℃下能顺利萌发，其萌发率分别是90%和92%。不过，35℃下的萌发率较低(37%)。当种子干燥脱水后，种子含水量下降至33.79%时，种子萌发率降低至50%；当种子含水量进一步降低至25.73%时，其萌发率仅有6%。这表明蒲桃种子是脱水敏感性种子。此外，在7~9月的生境播种实验中，土壤表面的种子均未萌发，埋于土壤之中且浇水的蒲桃种子的出苗率也很低(31.5%)。综合而言，蒲桃种子对干燥脱水非常敏感，极可能是顽拗性种子；在夏季成熟后，散落的种子在高温与干燥胁迫下难以萌发，这可能是其生境缺失幼苗的重要原因之一。

Abstract: Seed is one of the important germplasm resources, and it is difficult to scientifically store them if desiccation tolerance of valuable seeds is not determined. To ascertain whether polyembryonic rose apple (Syzygium jambos) seeds were sensitive to drying and their suitable germination temperature for better preservation and utilization, this study conducted drying and germination experiments on mature rose apple seeds. The results showed that mature rose apple seeds had a high initial moisture content (50.15%) and germinated well at 30˚C and 30/20˚C, with germination percentages of 90% and 92%, respectively. However, the germination percentage was low (37%) at 35˚C. When seed moisture content decreased to 33.79% after drying, the seed germination percentage declined to 50%. When the seed moisture content further decreased to 25.73%, the germination rate was only 6%. It was inferred that rose apple seeds were sensitive to desiccation. In addition, the seeds sown on soil surface did not germinate at all in the habitat from July to September, and the seedling emergence rate of rose apple seeds that were buried and watered was very low (31.5%) in the habitat. Taken together, rose apple seeds are highly sensitive to drying, and are likely to be recalcitrant. After maturing in summer, dispersed seeds are difficult to germinate under high temperature and dry stress, which may be one of the important reasons for seedling deficiency in the habitat.