Developing tree species in local area, strengthening selec-tion and breeding, especially introduction and tameness of color-leave plants to stress city gardens' features of Beijing are the important tasks on selection and development of city greening tree species in Beijing at present.
认为发展乡土树种,加强选种、育种工作,积极开展彩叶植物引种驯化,突出北京城市园林特色,是当前北京城市园林绿化树种选择和发展所面临的重要课题。
Breeding groups are being used to control inbreeding in a breeding population and to effectively achieve maximum genetic gains in some tree improvement programs of the United States.
在美国的一些林木育种项目中,育种群已用来控制种子园的近交、捕获最大的遗传增益的有效措施。
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