油松初级无性系种子园之所以能够产生遗传增益,是由于所选的优树无性系大多数具有优良的基因型。但由于在优树的选择过程中,受环境和随机因素的影响,总有一部分优树的基因型并不优良或者优良程度很低,所以在种子园内,这些优树无性系产生的子代没有或很少有增产效果,从而降低了初级种子园的增产水平。由于70年代建立起来的种子园,多数没有及时开展子代测定工作,因此,要通过子代 The reason why the seed orchard of Pinus tabulaeformis clones can produce genetic gain is due to the fact that most of the selected elite tree clones have excellent genotypes. However, due to the environmental and random factors, there are always some excellent trees whose genotypes are not good or have a low level of goodness during the selection process of the elite trees. Therefore, in the seed orchard, the progeny resulting from these elite tree clones There is little or no stimulation effect, which reduces the yield of primary seed orchard. Due to the seed orchards established in the 1970s, the majority did not carry out the measurement of offspring in time. Therefore,