Among the many regulatory substances in use we have controllable and selective herbicides . 在所有的许多调节物质中,有控制性的和选择性的除草剂。
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In one way or another all these various regulatory substances intervene and exert recognizable effects upon the overall course of plant growth and development . 所有这些不同的调节物质以这种或那种方式参与植物生长发育的全过程。