在林业生产上,从本世纪50年代以来,各国对选用良种,实现林木栽培良种化的工作,已正式提上日程。由于林木生产周期长,面积大,经营分散等特点,所以从选用良种入手,以缩短林木栽培周期,就受到越来越多的重视,也收到显著的成效。解放以后,尤其是无产阶级文化大革命以后,我国林木良种选育工作,得到飞跃的发展,在杨树、桉树、杉木、泡桐、池柏、油茶、核桃等速生树种和经济林木上,选育出一大批优良品种,各省、市、自治区也纷纷建立了大面积的良种基地,树木育种工作,呈现出一片欣欣向荣的局面。在学习与总结上述成就的基础上,并参考国外的经验,这里我们就什么叫良种、怎 In the field of forestry production, since the 1950s, various countries have formally put on the agenda the selection of improved varieties and the improvement of tree planting and seed production. Due to the long production cycle, large area and diversified management of forest trees, more and more attention has been paid to trees cultivation cycle to shorten the period of forest cultivation, and remarkable achievements have also been received. After the liberation, especially after the great proletarian cultural revolution, the breeding of tree seeds in our country has made rapid progress. Breeding of fast-growing tree species such as poplar, eucalyptus, fir, paulownia, cypress, camellia, walnut, and economic trees, A large number of fine varieties, provinces, municipalities and autonomous regions have also established a large area of ​​seed base, tree breeding work, showing a thriving situation. On the basis of learning and summarizing the achievements mentioned above, and referring to the experience of other countries, what are we called good seeds here?