<正>本研究发现,碘化钾是杉木种子衬比射线检验的最佳衬比剂;衬比过程是:杉木种子在自来水中浸泡16h;吸干种子表面水分,在40％的碘化钾溶液中处理2 h;在流水中冲洗5～6min后在70℃下干燥4h。研究结果表明,胚和胚乳(雌配子体)发育良好且未被碘化钾浸渗的种子都有生活力。用X射线衬比法测定的34份杉木种子发芽能力(X),同它们的实际发芽率(Y)相当一致。它们的关系是Y=-1.5+0.998X,r=0.97。

Potassium iodide was found in a pilot experiment to be the most suitable contrast agent a-mong 15 chemicals for Chinese fir seeds. It was confirmed that the best X-ray contrast method for Chinese fir seeds was as follows; Seed sample was soaked in tapwater for 16 hours at 25°C. After superficially drying, the sample was treated with a 40% aqueous solution of KI for 2 hours. Afterwards, the seeds were washed in slowly running water for 5-6 min. The extra water was wiped off the seeds. Thereafter, the seeds were dried at 70°C for 4 hours. The dried seeds were then radiographed under the following condition: kV=20, mA=3, exposure time=60s, focus-film distance=25cm. A seed with fully developed endosperm and embryo free of impregnation was considered as viable seed, Ger-minability could be thus calculated as ratio of the number of viable seeds to the total number of seeds in a sample. The germinabilities (X) of 34 Chinese fir seed lots evaluated by X-ray contrast method were very close to their germination percents (7) by the standard method. The relationship is Y=-1. 5 + 0. 998X(r=0. 97).