一、引言近20年来,世界各地已普遍开展了在树木选择基础上,建立种子园的工作。许多国家以建立种子园,为改良森林种子基因型,获得较大遗传增益的途径。分析欧洲赤松种子园内自交、异型杂交和天然授粉等所产生的种子的空种频率差异,Johnson(1972)发现,至少有1%有生活力的种子是自交的。Rudin 和 Lin- I. INTRODUCTION In the recent 20 years, the work of establishing seed orchards has been carried out on the basis of tree selection in various parts of the world. In many countries, the establishment of seed orchards is a way to gain greater genetic gain in improving the forest seed genotype. To analyze the difference in the frequency of empty seeds of seeds produced by selfing, crossbreeding and natural pollination in the Japanese red pine seed garden, Johnson (1972) found that at least 1% of the viable seeds are selfed. Rudin and Lin-